After some preliminary considerations about its place in Aristotle’s ethical treatises, the discussion focuses on Aristotle’s biology. Here we learn that natural philia, couched in terms of a biological praxis rather than a trait of character, is widespread in the animal kingdom, although in different ways and to varying degrees. To account for such differences, Aristotle establishes a Scala Philiae in two different biological texts—Historia Animalium and Generation of Animals—where natural bonds in animals are classified in view of their strength and duration. Each level of Aristotle’s Scala is examined. Finally, the argument returns to Aristotle’s ethical and political texts, drawing greater attention to the biological mechanisms that underlie natural philia in human beings. I conclude that natural philia provides one fundamental biological building-block of Aristotle’s ethics and politics.This article is the first one to offer an investigation, from a biological perspective, of “natural  Nicomachean Ethics (VIII-IX), the fact remains that until recently it was widely neglected by scholars. It is true that the literature on the topic has increased dramatically in the last few decades  that plays such a foundational role in Aristotelian ethics but rather as a specific biological activity (praxis)—a key distinction that has yet to be explained. This is what I call “natural philia”, or alternatively, in modern parlance, “kin-based philia”.4The present investigation seeks to fill precisely this gap in Aristotle scholarship, while also arguing for a more substantive thesis: that Nicomachean Ethics, drawing special attention to the place of natural philia along with certain difficulties associated with it. In section philia as outlined in his biological thought in order to trace its roots in his zoological treatises . Finally, in section philia in mind, with the intention of exploring further how natural philia is conceptualised specifically in relation to the human species and within a broader account of ethical character. My emphasis will remain on the underlying biological mechanisms of philia, though. I conclude with some brief remarks on the implications that Aristotle’s analysis of natural philia carries for his theory of moral development.My strategy runs as follows. The analysis splits into three main sections: I begin, in section Nicomachean Ethics (NE), Aristotle turns to the discussion of philia, commonly translated as “friendship”. Philia is portrayed from the opening of Book VIII as either a moral virtue in its own right or at least as involving moral virtue. Either way, Aristotle observes, “it [philia] is most necessary in life” (VIII.1 1155a3-4). It is certainly telling, and hardly incidental, that Aristotle begins the treatment of philia by stressing not that philia is an absolute necessity for the good or virtuous life—although he did regard it so indeed (NE IX.9 1169b8-22)—but that philia is an absolute necessity in life (period).In Book VIII of the NE VIII.1 1155a5-6 with IX.9 1169b10-22). Being the social animals that we are, our preservation and flourishing as animals is largely regulated by our interaction with other human beings, especially friends .EE VII.10 1242a7-9).ex hypothesi, we would still “come together just for the sake of living together” . A clear evidence of this natural tendency to socialise with others and integrate them as constitutive ingredients of one’s own life is of course philia (NE IX.9).As the argument unfolds, we soon discover that Aristotle’s rationale for this opening claim is that human beings possess an innate tendency, deeply rooted in our nature as social animals, to establish close and enduring bonds with others, to the extent that “no one would choose to live without friends, even if he had all remaining goods” . For present purposes, this is the specific bond that I shall identify as “natural philia”. Aristotle is careful to distinguish natural philia thus understood from all previously identified kinds, arguing that it may well be worthy of a separate treatment altogether (NE VIII.12 1161b12). He is not very explicit as to exactly why natural philia is to be tackled separately, but we can gather his understanding on the matter from the argument that immediately follows in NE VIII.12.As can be gathered, Aristotle’s treatment of philia, filial attachment is not explained primarily by the reciprocal exchange of some good, whether utility, pleasure or virtue, but rather by reference to something prior to any form of chosen reciprocal association, namely, a common biological make-up. In Aristotle’s own words, this relationship is “suggenikê philia” , viz., literally, philia among those who are united by one and the same genos or “common descent”. Elsewhere he also portrays it, even more graphically, as an especially strong social attachment where individuals share the “same blood” or “same root” . We shall see that this bond is not unique to human beings but widely spread in the animal kingdom—Aristotle recognises one of its clearest manifestations in the attentive and caring attitude that progenitors, and mothers in particular, show towards their offspring . It becomes apparent, therefore, that natural philia, in the narrow sense just defined, is intimately associated in Aristotle’s ethical and political texts with specific phases of our life history: reproduction and breeding—I shall return to this point in sections More precisely, in the case of natural philia is not easy to reconcile with the overall classification of philia that we find in his ethical works—which may partly explain why it has been largely ignored by interpreters. If natural philia is to be a certain kind of philia at all, then it must surely possess the defining attributes that characterise philia across the board. Unfortunately, it seems to lack many of them—or so many critics believe. Before examining the biological mechanisms of natural philia in Aristotle’s zoology, it is thus advisable to address this initial difficulty first. Although this will require us to take a short detour from the main line of reasoning, the diversion is certainly worth taking, I think, if it allows us to gain a deeper understanding of both how Aristotle characterises natural philia in his ethics and what its place is within his general conception of philia.As often pointed out by scholars, Aristotle’s approach to natural philia at the pre-philosophical level—a common methodological move in Aristotle’s ethics  of philia in view of the relevant good at play: philia of character, philia of pleasure, and philia of utility (NE VIII.3).philia” is a case of mere univocity or whether there is a different semantic connection between these three kinds of philia such as non-accidental homonymy . Aristotle does provide a general account of philia in terms of—to put it roughly—reciprocal interchange of goods  based on the parties’ goodwill that does not go unnoticed by any of them (NE VIII.2). However, he also often suggests that philiai of utility and pleasure are philia “only by resemblance”  or even “by accident” (NE VIII.3 1156a17). These passages seem to commit him to the idea that philia is indeed predicated by analogy of those kinds which are not based on virtue and the mutual admiration of character.10By reflecting, if only as a starting point, upon how people de facto conceive of general characterisation of philia is the idea of a chosen reciprocal exchange of at least one of three goods . We thus obtain four essential components of philia in general : (C1) reciprocity, (C2) willingness and intention to cooperate, (C3) the involvement of at least one good that is reciprocated, (C4) and the awareness of the others’ philia for one. In those cases of genuine friendship, we can add (C5) living or spending time together. Understandably so, what has often troubled interpreters ever since antiquity  is the fact that some of these components are absent in natural philia, yet this does not prevent Aristotle from referring to it as “philia” all the same. Perhaps the clearest illustration of this difficulty is Aristotle’s description of philia between parents and young children. Aristotle explicitly indicates that it is not reciprocal (NE VIII.12 1161b24-26), and we are not given any evidence to conclude that it is virtue, pleasure, or utility that justifies calling them friends.philia from that of male and female, which may in principle include any of these shared items (NE VIII.12 1162a19-28). Yet the problem we must face now is that filial attachments connected with pair-bonding are apparently not the result of rational choice (Pol. I.2 1252a24-30), this being a key ingredient of philia in general .philiai of utility, character, and pleasure can indeed occur between husband and wife (NE VIII.12 1162a24-25), he also thinks that rational choice, which is not needed for pair-bonding, is responsible for the reciprocation of such goods (NE VIII.5 1157b29-32).Such exegetical issues notwithstanding, central to Aristotle’s philia in general—especially reciprocation and rational choice—can also be extended to natural philia in some way, or else he subsumes both his general characterisation of philia and natural philia under a broader notion of philia that covers the two of them as a general class. There is room for both strategies in Aristotle’s ethics. Let us elaborate on the first one.How are to make sense of these seemingly inconsistent passages? From a strictly logical standpoint, I see at least two possible ways: either Aristotle shows that, upon further reflection, the main attributes of philia does not presuppose rational choice and reciprocation. When Aristotle observes that pair-bonding philia is the result of a natural impulse in human beings that is shared with other animals and that therefore does not demand rational choice (Pol. I.2 1252a28), he cannot be claiming, without contradicting himself, that the union of husband and wife is not mediated by their rational faculty as human beings. It is more natural to read him as suggesting that whatever brings them together corresponds to a natural impulse that would remain operative with or without rational choice, as shown by the fact that it is shared with other animals that lack prohairesis. This natural urge is explicitly identified with a certain “impulse [of living beings] to leave behind something of the same kind as themselves” (Pol. I.2 1252a28-30). It is thus the impulse to reproduce, then, that ultimately brings male and female together, and to the extent that this impulse is widespread in the animal kingdom, rational choice is not required for its emergence. Crucially, it does not follow from this that rational choice does not play any role at all in pair-bonding philia among human beings. For one thing, as just noted, the philia of man and women may include virtue, utility, or pleasure, all of which cannot be reciprocated without the assistance of rational choice in Aristotle’s theory. For another, it is the impulse to reproduce that is said to exist without rational choice but not this particular relationship with this or that individual.Of special interest at this point is the suggestion that natural philia based on consanguineous kinship. Aristotle often portrays it as a spontaneous natural bond, common to most animals, that can only emerge between progenitors and offspring  required to perceive their parents as parents (compare Phys. 184b12-14). That granted, Aristotle also makes it clear that children will come to love their parents in return at some point in life (NE X.9 1180b6-7),NE VIII.7 1158b20-23; VIII.11 1161a15-17). As we shall see in section philia matures in time, parents and children will eventually establish a deliberate normative relationship based on role-specific demands which they could easily ignored if they choose to. There is no need to broach the numerous cases of legal disputes, well-documented by the Attic orators, between fathers and sons in Greek courts. Aristotle himself is entirely aware that tensions and struggles between each other may easily emerge . In the case of human beings, consequently, to the extent that even our natural ties must be maintained and cultivated, there must also exist an important prohairetic component supporting them along with some form of reciprocity.14Similar considerations apply to natural philia has become so problematic is that it is tacitly expected from this account that it must fit into his general tripartite taxonomy of friendship just outlined. Yet this expectation ignores the fact that this is not the only way Aristotle differentiates kinds of philia in his ethics. He also avails himself of two additional taxonomical criteria, that is, criteria that are not meant to refine and expand on the tripartite categorisation of philiai based on the relevant good involved but to lay out a new classification. Of these two additional taxonomical criteria, the first one distinguishes, to put it crudely, philia among equals from hierarchical friendships (NE VIII.7), whereas the second one, which is the most relevant for the task at hand, distinguishes natural from non-natural forms of filial attachment (NE VIII.12). It is worth emphasising that Aristotle’s threefold taxonomy of philia  is overlapping, and not just in the weak sense that some type of philia within one taxonomy may overlap with that of the other, but in the stronger sense that nearly every kind of philia discussed by him will of necessity belong to at least one class within each taxonomical scheme. Thus, for example, one and the same philia can be based on utility, include some kind of hierarchy, and respond to a natural inclination towards someone else. As it happens, this characterisation fits perfectly well into Aristotle’s account of philia between husband and wife . Other relationships based on natural philia may be either hierarchical  or among equals , but Aristotle is not explicit as to whether, and how, considerations of utility, pleasure, or virtue apply to each of them. In any case, once we rule out merely accidental equivocation, the fact that each taxonomical scheme is meant to provide a classification of one and the same phenomenon, philia, presumes that the criteria which are employed within one scheme cannot exhaust the phenomenon altogether. Consequently, even if we accept that natural philia lacks some of the main components present in non-kin philia—as just noted, already a major concession—this need not pose any serious threat for the coherency of Aristotle’s theory. These remarks, it is worth noticing, only establish that which is required to render Aristotle’s terminology intelligible; they do not identify a fundamental notion of philia common to all taxonomical schemes— whether univocal or analogical.It is however the second strategy mentioned earlier that really matters for present purposes. One of the reasons why Aristotle’s account of natural philia is, this is a notoriously difficult question which, if dealt with responsibly, would demand a separate discussion altogether. Before moving on to the next section, and to conclude the present detour, here I shall only say this much: there is a central psychological component which is characteristic of both natural philia and philia in the strict sense and which at the same time distinguish the two of them in particular from all remaining kinds.As for the more substantive question of what exactly this fundamental underlying notion (or notions) of philia in terms of the relevant good at stake, it was already noted that for Aristotle only philia of character can be said to be philia sensu stricto.philia of utility and pleasure are philia merely “by resemblance”, i.e., only insofar as they come to instantiate, to a greater or lesser degree, certain attributes that are characteristic of philia of character. As a case in point, it is because utility and pleasure are also essential to virtuous philia that relationships based on the mutually recognised reciprocation of such goods can be called “philia” at all .philia, we love our friends and we are loved by them in return. Loving someone as a friend—what Aristotle sometimes calls “philêsis”  or “philein” (NE VIII.8 1159a26-35)—means at least two things: firstly, that our object of love is not the utility or pleasure that our friend may produce (despite the fact that he certainly produces them) but the friend himself; secondly, that loving is an activity of the soul (IX.7 1168a19) which involves certain commitments and attachments to others that distinguish philia proper from other kinds of human associations. In Aristotle’s own words:The story goes something like this: when it comes to the classification of philia seems to consist more in loving (philein) than in being loved (phileisthai), as is indicated by the enjoyment a mother finds in love (philein). Sometimes she will give her own child to others to bring up, and though she loves him because she knows him, she does not seek to be loved in return, if it is impossible to have both. It seems enough for her to see the child doing well, and she loves him even if, because he does not know her, he gives her none of the things appropriate to a mother. Since philia consists more in loving, and we praise those who love their friends, it appears that loving is the virtue of friends” (NE VIII.8 1159a27-35).“But philia in the proper sense is characterised mostly in terms of its affective dimension (compare Rhet. II.4 1381a1-2). Simply put, friends feel love for each other, they feel it for the friend’s sake rather than their own sake, and in so doing they are loved in exactly the same way by their friends, too. Further, while philia cannot be reduced to this strong emotional component alone,the virtue of friends” (!). This move is crucial; it enables Aristotle to emphasise how it is that philia, despite its relational nature, can also be seen in some way as a virtue of character present in the soul of the individual. Minimally, it must be something that the soul of each friend is capable of doing instead of just passively suffering from, as is the case of being loved (compare MM II 1210b6-11). Finally, and most importantly, Aristotle suggestively argues that this active affective component of philia, which appears to be at the very centre of philia in the proper sense, is best exemplified by the unselfish concern and disinterested caring attitude that parents, and mothers in particular . To love someone as a friend is to love him for his own sake, for the sake of his own good, and this is precisely how parents love their children. Hence, while it must be admitted that natural philia is not reciprocal, at least initially, and to this extent there are good reasons to keep such relationships separate from character philiai, from the point of view of the psychological mechanisms involved, there is indeed some substantive common ground to character and parental philia, i.e., each friend loves and takes care of the other in the same manner that a parent loves her children, this being the distinctive sort of (virtuous) affection that ultimately constitutes, as the passage just quoted makes apparent, the psychological state of those who are friends.By contrast, Aristotle says that philiai of utility and pleasure are “accidental” (NE VIII.3 1156a16-17) precisely because (gar) such friends love—less radically, we may well say in this context: “like” or “appreciate”—the other party for the sake of their own benefit and not for the sake of the friend’s benefit (VIII.3 1156a14-17).18In this passage, ar Ward, , show tophilia and some of its well-known difficulties in Aristotle’s ethics. I will have more to say about this in sect. philia manifests itself in human beings is unique, natural philia itself is not. There is a fairly continuous and coherent account of natural philia in Aristotle’s thought, an account that originates in Aristotle’s biology but culminates in his ethics and politics.So much for the place of natural philia and philia among non-kin. His approach to natural philia in the biological works is an important piece of a more ambitious project. At the most general level, living organisms can be classified in view of four fundamental differentiae: their modes of life, their activities, their parts, and their natural characters (HA I.1 487a11-12). In the light of these four differentiae, one would expect to find an investigation of natural philia in the sections of Aristotle’s biology devoted to the natural characters of animals. Surprisingly, though, this is not Aristotle’s strategy. Instead, he investigates philia separately as a mode of life, as a trait of character, or as an activity.Aristotle observes that, just as human beings, animals are also capable of both kin-based philia is brought up in the biological treatises: firstly, as a natural trait of character (êthos) that distinguishes some particularly friendly (philêtikon) animals from others ; secondly, this time in connection with the mode of life (bios) of animals (IX.1 610a33-35), as an inter-species relationship of animals that, while sharing the same ecosystem, do not feed on each other, nor do they compete for the same resources ; thirdly, as a symbiotic relationship of animals that positively benefit each other “accidentally” by maximising their own self-interest (HA IX.6 612a20-23 with EE VII.2 1236b5-10)praxeis of animals, philia is examined in connection with different mating and breeding strategies . It is the fourth occurrence that primarily matters for an analysis of natural philia as defined in section philia is a kind of activity, it seems advisable to say a few preliminary words on Aristotle’s conception of praxis in his biology—a fairly neglected subject in any case—before we examine what sort of praxis natural philia is.All in all, we find four different contexts where praxis in Aristotle’s biology. On occasions, moreover, he seems to treat praxis and bios interchangeably (Pol. I.4 1254a7) or at least as constitutive ingredients of one and the same aspect of living beings that cannot be treated in isolation from each other  where Aristotle offers certain formal criteria to classify praxeis in animals: some are common to all animals, others vary according to general kinds, and yet others according to forms within those kinds. Once this initial difficulty is duly acknowledged—i.e., a definition of praxis is not available in the texts—we must proceed obliquely and infer Aristotle’s views from the concrete application and use he makes of this differentia.We are never given, so far as I can see, a clear-cut definition of do. Therefore, they must be distinguished from pathê, that is, passive capacities of living organisms whereby things can happen to them. But they are the sort of thing that animals carry out not just individually and contingently but regularly qua members of a specific natural kind. Thus, for example, sleep and growth are affections (PA I.1 639a20), whereas reproduction and feeding are activities (HA VIII.12 596b20-23). By “natural kind” I mean to suggest, quite broadly and flexibly, whatever level of generality that is appropriate for the analysis of a given activity relative to a group of living organisms: some will be present in all living beings, while others only in some . Aristotle (in)famously argues for a strong teleological connection between the activities of an animal and its particular morphology: parts are for the sake of activities and not the other way around . This explains why, for instance, there is so much variation in the size and form of teeth across species; this depends not only on what they eat but also on whether they use their teeth to defend themselves from attacks (PA III.1 661b). On other occasions, however, where morphological variations are not strictly functional, these may be explained in terms of the underlying material constitution of the animal .21Let us start with the basics: activities are the sort of things that animals philia in his biological system. Because this distinction is fleshed out teleologically, to the effect that second-order activities are performed for the sake of first-order activities, it is convenient to first elaborate on the teleological subordination of second-order to first-order activities. Given that activities are that for the sake of which parts exist, the subordination of activities is coherently paired with a subordination of the respective parts involved (PA I.5 645b28-32). In a nutshell, a teleological subordination of activities is accompanied by a corresponding subordination of the parts that exist for the sake of those activities, and hence, by mere transitivity, of parts to activities other than the ones that explain their existence directly. Taking Aristotle’s theory of respiration as an illustration, we can conclude that the lungs exist in order to cool the blood, and the windpipe, which allows for the circulation of air to and from the lungs, exist for the sake of the lungs, so the windpipe exists, too, for the sake of cooling the blood.22Crucially, Aristotle operates with a distinction between first-order and second-order activities which is key for appreciating the function and place of natural all other activities of a given living organism are done. Because these activities are truly final, we can accordingly call them “constitutive” or “irreducible” first-order activities. The point is made in two different passages of HA: in one we learn that “[t]he life of animals, then, may be divided into two activities —procreation and feeding; for on these two activities all their interests and life concentrate” (VIII.1 589a2-5), while the other states that “[t]he activities of animals are all connected with either reproduction and the rearing of young, or with procuring a due supply of food” (VIII.12 596b20-23). In both passages, Aristotle is talking about animals and not plants,., reproduction and nourishment, are predicated of all animals in virtue of their nutritive capacities (HA VIII.1 588b24-28 with DA II.4 415a23-b3). Of course, this is not to say that such basic activities will manifest themselves identically in all living organisms: not only is (say) the reproduction of plants and that of animals based on diverse biological mechanisms, but there are also significant differences in the reproductive systems of animals themselves. At the most general level of analysis, if we were to take Aristotle’s tripartite stratification of life in the De Anima as a point of reference, the complexity and sophistication of first-order constitutive activities begin to increase considerably, both qualitatively and quantitatively, once sensibility enters the scene:Now Aristotle specifies a restricted set of essential activities for the sake of which i.e.reproduction] are common to all [living beings]. But when sensibility (aisthêsis) is also added, then their lives will differ from one another as regards mating through the varying amount of pleasure, and also in relation to labour and ways of rearing their young.” (HA VIII.1 588b27-30).“The activities of this sort  inculcates this [caretaking perception] only until the moment of birth; in others, even until the offspring reaches its perfect development; and in those that have more intelligence, until its upbringing is completed. Those which are endowed with most intelligence show intimacy and attachment towards their offspring even after they have reached their perfect development (human beings and some of the quadrupeds are examples of this); birds show it until they have produced their chicks and brought them up” .philia only until the moment of birth (753a9-10). The assertion is enigmatic on two counts: firstly, it presumes not only that natural philia need not be directed at the new-born offspring but also that it is already operative in female progenitors from the moment of fertilisation or shortly afterwards, even before the offspring has been born. Secondly, it also presupposes that natural philia remains operative only until the moment of birth in some animals. But how could this possibly be?At the most basic level—call it “L1”—we learn that some animals experience natural Scala Philiae is framed. As the immediately preceding lines make apparent (752b35-753a7), the broader context is meant to offer an explanation of how the eggs of birds (and some oviparous quadrupeds) are formed. Whatever the details of that explanation are, at least in the case of birds, birth is preceded by an incubation period whose successful culmination depends on the “caretaking perception” of the mother: for the eggs to hatch, the mother’s heat is required. This is not to say that pre-birth natural philia is only restricted to the reproduction of births, however. For one thing, the distinctive mark of species belonging to L1 is not that they exhibit natural philia even before birth, though they do so indeed, but rather that it only lasts until the moment of birth. For another, elsewhere Aristotle recognises that during pregnancy (or incubation) female mammals also undergo all sort of key biological changes, including behavioural ones, that are necessary for a successful birth. In the Politics, for example, we are told that “unborn children evidently draw resources from their mothers, just as plants do from the earth” . Another illustration of pre-birth natural philia at work is provided by the female deer that cautiously takes all the necessary precautions to give birth along the sides of busy roads so that predators become intimidated and do not attack the new-born offspring (HA IX.5 611a15-23). To the extent that such behavioural and physiological changes are ultimately aimed at the survival of the offspring rather than the mother’s,already early manifestations of the “caring attitude” that nature instils in females.An answer to the first question can be extracted from the general context within which the philia extends only until the moment of birth (compare HA VIII.1 588b24-589a2). This time he cannot be alluding to birds in general, though. For the passage from GA III.2 just quoted teaches that birds show natural philia “until they have produced their chicks and brought them up” (emphasis is mine). What he could this possibly mean? Although we are given no examples, my suggestion is that Aristotle may be referring to so-called “superprecocial” animals that separate off immediately after birth—now we know that some birds  do belong to this category indeed.The second question is certainly more puzzling. Aristotle claims that in some species natural Scala Philiae—let’s call it “L2”—constituted by animals that display natural philia after birth, extending the filial bond throughout the rearing period until the progeny reaches biological maturation. These animals feed their offspring for some time but they abandon them as soon as they are capable of feeding themselves. Most importantly, no filial attachment remains thereafter. In such species, consequently, the durability of the filial bond is constrained by biological self-sufficiency, being thus directed exclusively at survival. In exceptional cases, moreover, natural philia pertains to the survival of both mother and offspring, as evinced by the deterioration that mother hens suffer if they fail to take due care of their eggs. This amounts, Aristotle observes, to “a deprivation of a natural endowment” (GA III.2 753a1-2 compare HA VI.2 560b6-7).Next, Aristotle also distinguishes another level of the Scala Philiae—again, for ease of reference, let’s call it “L3”. At this level we find animals that are characterised by greater intelligence  and memory (mnêmê), such as man and certain quadrupeds. They show both greater affinity (synêtheia) and philia towards their offspring even after they have reached biological maturation (GA III.2 753a9-17 with HA VIII.1 588b24-589a2). Predictably, these animals exhibit greater levels of socialisation, too; they lead more political lives (HA 589a2). Here natural philia is therefore not restricted to the survival of the offspring alone.27Finally, Aristotle identifies yet a third level of the Scala Philiae in place, it is worth investigating what the relevant explanatory factors are that account for the transition from one level to the other. The only one that is explicitly brought out by Aristotle himself is cognition, which is mentioned to explain why animals in L3 have more enduring filial attachments than those in L2—I shall return to this below. This observation, however, is not sufficient for appreciating the various details and subtleties behind Aristotle’s Scala Philiae. On the one hand, the reference to cognition is made in order to account just for the transition from L2 to L3, thus leaving open whether the same criterion should be applied to L1-L2; on the other, we are not told how it is that cognition alone can give rise to a completely new level of natural affiliation, namely, L3. Before addressing these two issues, it is worth pointing out that the explanatory factors underlying Aristotle’s Scala Philiae are multiple and different in nature: the ecology of a species, its life history, the psychological character of each sexual partner, to name some of them. For reason of space, I shall not discuss the way ecology and animal character correlate with, and are partly explanatory of, each level of the Scala Philiae. I wish to draw greater attention instead to how both the life history and intelligence of a given species determine its position in the Scala.28With this rough outline of the philia: a “caretaking perception” (aisthêsis epimelektikê) towards offspring. In practical terms, this perception is materialised through the supply of what is needed for the survival of the offspring, including, in extreme circumstances, the life of the parent herself (EE VII.1 1235a33-35). Save for one remarkable exception, we are given no evidence to conclude that natural philia may emerge in animals that are not rearing—or have not reared–philia is to be found especially among progenitors, it is not always restricted to them alone since in some species belonging to L3 the offspring will reciprocate once they grow up, thereby helping old progenitors in return. Among those animals that exhibit “lagged reciprocity”, as it were, between offspring and progenitors, Aristotle mentions, in addition to human beings (NE VIII.7 1158b20-23), old storks and bee-eaters, each of which is fed by “their grateful progeny” (HA IX.12 615b23-27). At first, Aristotle’s two examples are not easy to accommodate within his broader Scala Philiae. Conforming to the version of it outlined in GA III.2, we learn that birds in general are to be placed within L2, whereas only man and some species of quadrupeds, that remain unnamed, belong to L3 (753a11-17). In view of such passages, we are compelled to assume that L2 covers most but not all birds, while examples in L3 are not meant to be exhaustive.Let us begin by examining in greater detail what is perhaps the distinctive mark of natural Scala Philiae we are dealing with, in most species it is the female, predictably enough, that is the primary source of natural philia. Even in those species where biparental care is practiced, such as ours, natural philia is still more intense in mothers. Aristotle conjectures that this is due to the great difference between male and female in parental investment, on the one hand, and parental certainty, on the other . There are however some exceptional instances, such as certain species of fishes, where natural philia is ascribed to the male progenitor exclusively (HA X.37 621a20-29 with VI.14 568a14-17). This observation seems to be in broad agreement with what we currently know about parental care in fishes , would instil a caregiving attitude in some progenitors only until birth (= L1), while in others until upbringing is complete (= L2). There is every reason to believe that natural philia after birth is simply not necessary for that offspring to thrive and survive, hence they must already be mature enough to fulfil their most basic needs on their own. In contrast, the longer it takes for a species to reach biological self-sufficiency, the stronger natural philia will be for the survival of that species’ progeny. From this perspective, we can recognise a direct correlation between the intensity of natural philia and the altricial-precocial spectrum. Among altricial animals, human beings are a particularly conspicuous example . As a pertinent side note, it is worth remembering that the perinatal mortality rate was also extremely high in Ancient Greece, this being the main reason, Aristotle himself reports, why children are first given a name on the seventh day after birth (HA VII.12 588a5-10).Pol. VII.17 1336b37-40) .33It is otherwise hard to explain why nature, which does nothing in vain as Aristotle often reminds us  is specifically introduced in Aristotle’s Scala Philiae as a predictor of the endurance of natural attachments in animals. In other passages, however, the link between intelligence and natural philia is approached from a different angle. For example, in a different context, where Aristotle is concerned with the biological analogue of technical intelligence, he marvels at the cognitive abilities of swallows , adducing as partial evidence of their intelligence (“dianoia”) a description of how carefully they proceed when feeding their chicks, aptly discriminating between those that are in need from those that are not (HA IX.7 612b25-29). Another illustration of how intelligence increases the efficacy of natural philia is delivered by the behaviour of female deer described earlier: they astutely give birth along the side of busy roads with the purpose of keeping predators away (HA IX.5 611a15-23). Surprisingly enough, this kind of connection between philia and cognition is not the main issue in GA III.2 753a9-17 and HA VIII.1 588b24-589a2 where intelligence relates instead to durability of natural attachments rather than efficacy of brood and rearing care.What about the role of cognition in the intensification of natural in these passages .philia becomes stronger and longer by making parental investment more demanding and enduring, but rather that in more intelligent animals the filial bond remains active even after upbringing has been completed. The allusion to memory (mnêmê) in HA VIII.1 588b25-589a2, as one of the cognitive factors that contributes to the prolongation of natural philia beyond biological maturation (= L3), implies that animals of greater intelligence are capable not only of recognising at some point of their ontogeny who their parents are—even in human beings, this may take some time, NE VIII.12 1161b25-26—but also of carrying that information with them well into adulthood. As a result, in such species, what initially developed as a unilateral caregiving bond from progenitors towards offspring becomes an instance of lagged reciprocity. In human beings, moreover, this also allows for multigenerational kin recognition, as we shall see in the next section.It is tempting to read Aristotle along modern lines and conclude that more intelligent species require a longer maturation period as well as greater parental investment.philia in Aristotle’s ethical and political texts, I hope so much can be granted: this should be understood not in isolation but as part of a richer and subtler picture about the biological foundations of human socialisation, this time framed within a richer analysis of moral character and the common good. The ethical and political treatises take up the subject precisely where the biological works left it: once we know that human beings are part of L3 in Aristotle’s Scala Philiae, now we are in a position to inquire into the unique manner in which natural philia manifests itself in our species.Let us now return to Aristotle’s ethics (and politics) with this analysis in mind. Whatever else may be said about natural philia may well be worthy of a separate treatment (NE VIII.12 1161b11-13). To wit, it is a form of biological praxis rather than a trait of character.philia may display many forms in human beings, but all of them “appear to be derived from paternal philia” (NE VIII.12 1161b17). Although Aristotle only mentions “paternal philia” in this context, there is compelling textual evidence to conclude that his observation must be extended to parental philia more broadly. Immediately after stating that all forms of kin-based philia derive from paternal philia (“ek tês patrikês”), he adduces as evidence the fact that both parents (hoi goneis) love their children as themselves (NE 1161b18-19). The thought is not only that parental philia serves as a paradigm of filial attachment in general in virtue of its unique emotional component, as suggested in section NE VIII.12 1161b27-29).EE VII.1 1235a31-35; EE VII.8 1241b4-9; NE IX.7 1168a24-26; NE VIII.12 1161b26-27). The relationship of parents and children—they are suggenikos, hence related to each other in the closest possible way—is subsequently extended, if only partially, to the bonds that unite siblings to each other. In so far as siblings share a common progenitor, they are in a sense the same (tauto) too, albeit in different bodies (NE VIII.12 1161b30-33).NE VIII.12 1161b33-35; 1162a9-15).To begin with, the foregoing considerations enable us to have a better grasp of why Aristotle suggestively tells us that natural NE VIII.12 1162a2-4). It is in this concrete sense that relationships among kin are literally derivative from parental philia.entitled to give pride of place to kin-based relationships over others but also that they are even required by justice to treat people differently, depending on the degree of kinship involved .Next, Aristotle steps out of the nuclear family so as to make room for weaker biological ties with distant relatives. Their filial attachment resembles that of siblings by their relative proximity to a common progenitor—who is this time further removed in the genealogical tree. Aristotle remarks that the strength of the bond among kin is in each case determined by a principle of direct proportionality: the closer two relatives are to a common progenitor, the stronger the bond between each other . He expresses himself differently in his biological works, however, where both monogamy and biparental care are additionally ascribed to non-human animals, for example swallows and dolphins . But even if we add the rider that most but not all animals separate off after reproducing, thus qualifying Aristotle’s remark about the mating system of non-human animals in his ethics, his fundamental thesis about human reproduction remains, for it is still the case that it is only in human beings that reproduction eventually leads to the generation of the household (oikia) (NE VIII.12 1162a16-19). The household corresponds, in other words, to the rather unique way in which natural philia manifests itself in our species. Aristotle reminds us that we are, first and foremost, household animals , and that the household is a kind of philia (VII.10 EE 1242a27-28).40We can see that Aristotle’s account of natural archai kai pêgai) of friendship, of political organization and of justice” (EE VII.10 1242a40-1242b1). On the other hand, the household arises, unlike the political community, not in order to complete our nature as rational and political animals but in order to satisfy our basic biological needs as animals, ranging from reproduction to nourishment . In Aristotle’s own terminology, “man is by nature [a] pairing [animal] even more so than [a] political [animal], in as much as the household is prior to the city, and more necessary, and reproduction is more widely shared with animals” (NE VIII.12 1662a17-19).The household occupies quite a unique place in Aristotle’s ethical, political, and biological thought, existing at the intersection of Aristotle’s biology and ethico-political thought: the household is a socio-economic institution, indeed the atomic unit of the city-state, but it is also a biological phenomenon that differentiates the human mating system from that of other animals. On the one hand, the household contains the seeds of moral virtues that make social life possible: “in the household are first found the origins and springs . It is in this sense that the household is “more necessary” than the political community, whose main goal is, by contrast, not only to enable men to live but to live well and make citizens good through proper legislation .I cannot do justice to the multiple implications that Aristotle’s account of the household, understood as the locus philia and parental philia: in those species such as ours where biparental care exists, pair-bonding is greatly reinforced by shared offspring, for “children seem to be another bond (…) children are a good which is common to both, and what is common holds things together” (NE VIII.12 1162a27-29). If we add to this observation that the upbringing of children is exceptionally long and demanding, as compared with that of other species, we can easily understand how parental philia further reinforces pair-bonding philia. Undoubtedly, this partly explains why human beings, unlike most animals, remain together after mating, generating the household as a result. Elsewhere Aristotle adds yet another mechanism that reinforces natural philia in our species. He often suggests that the amount of effort and time that parents are willing to devote to their children is largely determined by parental certainty.philia simply cannot develop in human beings, nor can ethical virtue for that matter. Let us conclude the discussion with some final comments on this point.Underlying Aristotle’s account of the household it is possible to detect a direct link between pair-bonding NE II.1, are not natural in the sense that we are born with them, but nor are they contrary to our inborn nature. We are born with the natural capacity to learn them, and we learn them in actu exercito through habituation; just as we learn to play the lyre by playing the lyre, so too we learn to be just by doing just things (NE 1103a31-b2). For the acquisition of a given virtue, it is always preferable to gradually incorporate habits as soon as the child is in possession of the required psychological profile to have that specific habit (Pol. VII.13 1336a18-19). During early stages of moral development, where human psychology differs very little from animal psychology (HA VIII.1 588a31-b3 compare Pol. VII.15 1334b20-25), habituation must be inculcated and guided someway from the outside. Until recently, it was widely believed by developmental psychologists that this process was mostly mediated, rather spontaneously, through children’s social interactions with their peers, but more recent findings seem to align with Aristotle’s take on the matter: it is in the family, as noted earlier, where we find the true “origins and principles” of philia and justice (EE VII.10 1242a40-1242b1).42The virtues of character, Aristotle famously argues in his unique personality and needs—something that public education, which in any case begins after seven years old (Pol. VII.17 1336b1-2), cannot afford (NE X.9 1180b3-13). On this model of moral education, parents may of course transmit virtue through active and deliberate teaching (NE VIII.12 1162a6-7 with MM 1211b38), but it is mostly through their role as moral exemplars that the job gets done. From early childhood, humans have an innate tendency to imitate what they see and hear (Poet. 1448b5-9), and it is reasonable to assume that this tendency will be directed towards their parents in the first place. Aristotle argues that the shared life of good friends serves as a “sort of training in virtue” (NE IX.9 1170a11-12). Kin relationships, especially within the nuclear family, are surely no exception to this general principle, for we live and interact most of the time with kin (EE VII.1 1234b34-1235a2). Unsurprisingly, then, what parents say and do will have a decisive impact on children’s appreciation of virtue and vice (NE X.9 1180b3-7).The disinterested love of mothers for children will take care of their needs as young infants, while the father’s character will serve as an ethical model to be emulated later in life.r Poet. 18b5-9, anphilia. It is true that Aristotle does not arrive at this conclusion by means of a comparative analysis with the mode of life of closer taxa in the phylogenetic tree, as contemporary biologists usually proceed. But he does envisage a hypothetical scenario where natural philia is forcefully regulated in our species and eventually banished through cultural conditioning. This is indeed the objective of Plato’s communist dystopia, as Aristotle might have said, where all traces of family ties are deliberately eradicated, without much success in his eyes, for the sake of greater social cohesion. Plato sets out to remove natural philia from the polis by preventing individuals from acknowledging their natural bonds; in his ideal political community, neither parents can know the identity of their children nor can children know that of their parents. Questions of ethical legitimacy aside, Aristotle thinks that Plato’s project will have to face some practical difficulties, one of them being that philia will become “diluted” in such social circumstances (Pol. II.4 1262b15). The main upshot is that parents, under conditions of uncertainty, will lose any incentive to take care (epimeleia) of children in the way that virtue demands . That is, once parental certainty is removed (II.3 1262a5-6), the “caregiving perception” that nature equips progenitors with is also eliminated along with it, and there is no alternative social bond that could replace the investment and attachment that natural philia carries in human beings. At the same time, because an essential component of the relationship between parent and children is the intimacy and attachment that only biological kinship can grant , both the admiration of children for their parents and the critical role of parents as unique moral exemplars will be threatened.Crucially, none of this would be possible without the assistance of natural logos, through which our moral sense emerges (Pol. I.2 1253a14-18), are still active in Plato’s ideal political community. And yet, Aristotle is emphatic to point out that virtue cannot develop in circumstances where natural philia is not allowed to follow its due course. This is not to say, nor to entail, that natural philia should go unregulated in the political community. On the contrary, precisely because of its pivotal importance for virtue acquisition, Aristotle devotes several sections of the Politics  to a careful analysis of exactly how legislation must regulate marriages and child-rearing in conformity with the distinctive life history and ontogeny of our species.Finally, and most importantly, in this hypothetical scenario, our inborn moral psychology remains pretty much untouched: the structure of the human soul and our capacity for philia places an important constraint on what is politically and ethically feasible (as well as desirable), thus acquiring a certain priority in the political and ethical domain. Politically, natural philia not only precedes the generation of the polis in time; it also represents an earlier evolutionary stage of human social life without which the political community could not have emerged in the first place. Ethically, on the other hand, it is not only the case that natural philia is temporally prior to our relationships with non-kin ; it is also that very first bond without which virtue cannot manifest itself later in life. To close the discussion, let us recall Aristotle’s own words one more time: it is in the household, which is a kind of philia , where we find “the origins and springs of friendship, of political organization and of justice” (EE VII.10 1242a40-1242b1).Instead, this is to say that natural


It has long been hypothesized that language acquisition may be impossible without innate knowledge of the structures that occur in natural language. Here, we show that a domain general learning setup, originally developed in cognitive psychology to model rule learning, is able to acquire key pieces of natural language from relatively few examples of sentences. This develops a new approach to formalizing linguistic learning and highlights some features of language and language acquisition that may arise from general cognitive processes. na, xx) languages, as well as for many languages studied in learning experiments. These results show that relatively small amounts of positive evidence can support learning of rich classes of generative computations over structures. The model provides an idealized learning setup upon which additional cognitive constraints and biases can be formalized.A major goal of linguistics and cognitive science is to understand what class of learning systems can acquire natural language. Until recently, the computational requirements of language have been used to argue that learning is impossible without a highly constrained hypothesis space. Here, we describe a learning system that is maximally unconstrained, operating over the space of all computations, and is able to acquire many of the key structures present in natural language from positive evidence alone. We demonstrate this by providing the same learning model with data from 74 distinct formal languages which have been argued to capture key features of language, have been studied in experimental work, or come from an interesting complexity class. The model is able to successfully induce the latent system generating the observed strings from small amounts of evidence in almost all cases, including for regular (e.g.,  One of the central debates in language acquisition is whether the structures of natural language are genetically specified or learned through experience. A key tool in this debate has been the use of formal mathematical analysis to determine what learners could or could not logically induce from the type of data they observe. Perhaps the most influential formal result is Gold’s Theorem , which i4917However, Gold’s negative learnability result is not widely accepted as relevant to human language , 23, 24.2529The view of learners operating over the space of computations can be motivated in language research by the diversity of linguistic constructions that must be acquired , 35, inc402945While the above work addresses learnability as a mathematical question, the central ideas remain relatively unconnected to contemporary ideas about mental representations. First, most theoretical analyses do not provide working implementations. Second, the representations prior analyses have used tended to focus on Turing machines or treated languages as abstract sets, but philosophers, cognitive scientists, and linguists have made a convincing case that compositional representations are natural for capturing human-like thinking –52 and c5357Our starting point—and the inspiration for our title—is Chomsky’s “Three models for the description of language”  which no63adorable, friendly, young monkey”) mirrors the structure in the simple formal language ϵ) or more successive adjectives (a) could be concatenated into a valid substring of English. In turn, this can be captured with a computational device with one internal state, which may optionally emit an a and return to the same state. Dependencies between determiner–noun pairs  mirrors the formal language a) requires a corresponding noun (b). The formal language If Mary cried then John was sad then John cares about Mary”  and then displaced  or the outcome of calling itself with an empty string as an argument, Valid compositions of primitives—those that respect the input and output types of each function—define an infinite set of hypotheses for learners to consider. For instance, the hypothesisH to be the space of all functions that can be constructed by composing the operations in D to be a multiset of observed strings, an idealized learner will compute a posterior distribution on hypotheses P(H) is given by a probabilistic context-free grammar (PFG) on the operations in P(H) implements a simplicity preference just as in induction of Turing machines  H and use its output set of strings. The problem with this is that it does not assign any partial credit to hypotheses which get most pieces of a string correct. For instance, if a hypothesis generates the strings aaa, it will assign aaab a nonzero likelihood equal to the probability of appending one b.Our implementation includes several important technical innovations that allow it to be scaled to interesting classes of formal languages. First, the choice of likelihood function Second, we allow the possibility that hypotheses involve multiple LOT expressions , here cana formal language shown above. The second function, x, and recursively concatenates the first element of x with a recursive call to itself, followed by a b. Because this is recursive on a shortening string . To do this, we developed a C++ library called Fleet (distributed under the GNU Public License v3 at https://github.com/piantado/Fleet). Notably, the Fleet implementation includes examples in other domains outside language, such as number learning . When precision is high but recall is low, the model undergeneralizes . Conversely, when recall is high and precision is low, the model overgeneralizes. When precision and recall are both 1.0, that means that the model has successfully learned the target formal language up to the approximation used to compute precision and recall. We also include a gray “Memorized (F)” line corresponding to what F score would be achieved by simply memorizing the observed data.We visualize results by approximating the posterior model-average precision and recall for the most likely strings generated by each hypothesis (see y axis) as a function of the amount of data provided to the model (x axis) (see Methods). In general, determining equivalence of hypotheses is uncomputable, so our precision and recall measures provide a quantification of how well the learner has acquired the target language, but we caution that, in all our figures, the results must be interpreted with care because these values are approximate.na, tal work , 105. ThCount is even, Bob, Pietro, and Johnny are a guitarist, accordionist, and troubadour, respectively” as well as examples from Mohawk’s use of noun stems in verbs  that mark the syntactic grouping and speed learning. aXb where the number of possible X elements varied. In X ranges over “Morgan & Newport”  follows by Gómez  and Gómeby Gómez  has examm Braine , 148 thaReeder et al. , table 2Overall, these results demonstrate that the model is capable of learning many of the patterns examined in experimental work. We expect that the model will not provide a tight fit to the details of human behavior in such tasks without incorporating additional cognitive considerations, including memory limits and perceptual salience.The problem faced in natural syntax is not just a series of unrelated, simple languages but that of learning a language that combines many patterns simultaneously. We next examine an English-like grammar that one might find in an introductory linguistic textbook,This target grammar includes several syntactic structures of English, including multiple expansions of a nonterminal type , tail recursion (in AP), transitive and intransitive verbs (in VP), sentential embedding (in VP), and prepositional phrases with embedded noun phrases. For instance, one string the model might observe is “d a n p d a n v t n v,” which corresponds to the part-of-speech sequence for a sentence like “The delightful accordionist by the old cafe knew that music heals.” As with all datasets, the model is not told there is a  grammar to learn, but is only told to construct something out of its primitives to explain the observed strings.The model’s learning curve for this grammar is shown in Although “poverty of the stimulus” arguments are often considered classic and foundational in linguistic theorizing , 155–159155160na, but the point is most clear for grammars which yield complex patterns of generalizations.Learners who operate over relatively unrestricted spaces show many hallmarks which have traditionally been attributed to universal grammar (UG), a domain-specific genetic endowment hypothesized to support language acquisition. Pullum and Scholz  identifyA huge body of literature has been dedicated to articulating and critiquing the subset problem of how it is that learners who use only positive evidence can avoid arriving at an overly general grammar , 165–170165na is infinite, and yet any data a learner sees—positive or negative—will be finite. Apart from explicit metalinguistic instruction, there does not seem to be any form of negative evidence or rephrasing that could lead learners to deduce this fact directly. Instead, learners must have an inductive mechanism that can consider the infinite language as a possibility, and weigh it against alternatives. We suspect that many structural aspects in language acquisition will have this flavor, where the precise form of evidence is not as crucial as the inductive biases learners possess and the hypotheses they consider.It is worth emphasizing that the assumptions of no negative evidence  have bee174Our results demonstrate that positive evidence not only can work in theory for discovering the right computation, but it works in practice, using simple, domain-general search techniques that have been applied broadly across cognitive science. At the same time, these methods are still in their infancy. We have only applied them to some of the basic descriptions of linguistic phenomena—ideas like recursion, nesting, simple context-free phrase structure, and context-sensitive dependencies. This work leaves open the question of how more-detailed kinds of phenomena may be acquired—for instance, long-distance dependencies in syntactic islands , 181. We182Our approach was motivated, in part, by Perfors et al. , who comIt turns out that this thinking is wrong, for a very interesting reason. The issue can best be understood by considering Jorge Luis Borges’ short story, “The Library of Babel” . Borges Our results also address a critique of domain-general approaches to language learning: It is often argued that children must possess constrained sets of hypotheses because there are many constructions that children simply don’t learn. However, our results also showed that there are languages that are difficult to learn, even for a universal model. This fact is not remarkable—it is inevitable. Only a few languages can have short description lengths or equivalently high priors, and so almost all logically possible languages will be difficult to learn. Consequently, there simply must be logically possible generalizations children never make, regardless of whether there are constraints specific to language or not. Learnability analyses have too often ignored these issues and conflated the class which can practically be learned with the total hypothesis space .This model tackles acquisition of language from a different perspective than connectionist models , 189, wh190197Finally, our results suggest that the Chomsky–Schützenberger hierarchy—popular for characterizing human and animal communication , 202—mayn length , 204 in n length , 205–207a and b) have different distributional properties. The goal of finding concise computational descriptions can likely be applied to other levels of linguistic representation, including part of speech categories or phonemes, where the relevant abstractions are thought to provide simple descriptions of apparent patterns. Generally, however, this work leaves open the question of what domain-specific constraints and knowledge are present in each of these levels of linguistic analysis and how those interface with domain-general capacities. At the very least, claims of domain-specific knowledge will only be tenable when formulated relative to demonstrable shortcomings in implemented domain-general learning theories.These results also point to several important directions for future modeling, experimentation, and theoretical work. Many aspects of learning—from words to grammars—may primarily require learners to find concise descriptions of observed data , 205. WhWhile this model provides a theoretical proposal for learning the patterns that govern sequences of discrete symbols, it is important to remember that real-life language learning is closely tied to language use –210, inc211The model described in this paper shows how learners could begin with a simple set of domain-general computational operations and create grammars in order to explain observed data. The model shows that implemented program induction techniques can build representations of provably different computational power, including regular, context-free, and context-sensitive hypotheses. It also shows that such learning requires surprisingly little data, and that positive evidence is sufficient. This model provides an inferential foundation onto which psychological or linguistic constraints—perhaps including pressures in memory or computational limitations —can be ax that is passed in is the empty string (ϵ); however, when one factor is called by another, it may pass in other arguments. In running, we enumerate execution paths down to a log probability of –15, 64 recursions, 1,024 program steps, or 256 different outputs. For the English example, we increased these bounds to output a larger distribution of strings. All of the code for specifying and sampling the input data and the input data themselves are available at the Fleet GitHub.In all formal languages, words and syllables in prior literature have been reduced to single characters so that the primary components that are generated are sequences of characters in a fixed alphabet. Languages are made probabilistic using generative  be the set of strings from a hypothesis h and let S(D) be the set of strings for a dataset D. Let h given the data, renormalized to sum to one over the top 500 hypotheses found . Then, posterior-weighted precision is defined asFor all languages but the simplified English grammar, we computed precision and recall using the most frequent 25 strings in the data and generated by each hypothesis. Let Because the simplified English grammar was substantially more complex than other languages, it was run on factor sizes of 1, 2, 3, 4, 5, and 6, with 15 threads each, for 7 d. Precision and recall was computed on the top 100 strings instead of the top 25 in order to better assess learning. In addition, these runs permitted more steps and smaller log probability in order to enumerate more strings.Several languages  introduced nonuniform sentence probabilities into the original grammar. This was done so that the strings yielded could be more easily evaluated in our metric of number of top strings. In this way, the tested languages were sometimes more skewed in distribution than the original references. While this makes the string set easier to identify by our metric, it also makes the distribution harder to match, since uniform distributions should be very easy for the model to learn.Supplementary File


Open Access funding enabled and organized by Projekt DEAL.The article “The work and training situation for young physicians undergoing specialty training in gynecology and obstetrics in Germany: an assessment of the status quo” written by Johannes Lermann, Julia Knabl, Johannes Neimann, Kevin Schulte, Kim Proske, Sarah Schott and Matthias Raspe was originally published electronically on the publisher’s internet portal on May 26, 2020 without open access. With the author(s)’ decision to opt for Open Choice the copyright of the article changed to © The Author(s) 2020 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third-party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit The original article has been updated.


With increasing numbers of people living with dementia relying on family to care for them at home, there is an urgent need for practical and evidence-based programs to support carers in maintaining their mental health and well-being. The objective of this study was to evaluate the acceptability and feasibility of a modified STrAtegies for RelaTives (START) program delivered online (START-online).A mixed-methods non-blinded evaluation of START-online (using Zoom as videoconferencing platform) for acceptability and feasibility  and quantitative evaluation. This occurred at the National Ageing Research Institute, in metropolitan Victoria, Australia.Twenty-nine eligible carers were referred, 20 (70%) consented to the study. Of these, 16 (80%) completed all 8 sessions, 2 completed only 3 sessions, and 2 withdrew. Carers’ qualitative feedback indicated that the therapist interaction was valued, content and online delivery of the program was acceptable. Feedback was mixed on the appropriate stage of caring.START-online was feasible and acceptable for carers, including those living outside of metropolitan areas who might otherwise be unable to access face-to-face programs. With the recent COVID-19 pandemic necessitating social distancing to avoid infection, interventions such as this one have increasing relevance in the provision of flexible services.The online version contains supplementary material available at 10.1186/s40814-022-00999-0. Only minimal testing was conducted in rural and remote settings.There remain some uncertainties regarding access to the required technology outside of metropolitan centres.What uncertainties existed regarding the feasibility?The START-online program was found to be acceptable to carers.n = 16/20) of recruited carers completed the program.80% , there is a corresponding increase in the number of informal carers required to support them to stay at home . InformaThe STrAtegies for RelaTives (START) program is a pragmatic, manual-based individual therapy program consisting of eight sessions over 8 months, aimed to provide improved coping strategies for carers of people with dementia, administered by psychology graduates without clinical qualifications . A blinded randomised-controlled trial (RCT) showed it to be a clinically and cost-effective program that improved total depressive and anxiety symptoms in carers of PLWD and quality of life, delivered face-to-face in the UK . These rThe primary aim of this study was to evaluate the acceptability and feasibility of the START-online program for carers in Australia in preparation for a future RCT. A mixed-methods unblinded before-and-after study design was conducted, drawing on Bowen’s approach to designing feasibility studies . A seconThe study was conducted at the National Ageing Research Institute (NARI), Victoria, Australia from March 2017 to August 2018.Carers were recruited from multiple sources including metropolitan and regional memory clinics, carer service providers, and support groups. To be eligible to participate in START-online, carers were aged 18 years or over, caring for a PLWD for at least 6 months, have a desktop computer, tablet or smartphone and able to communicate in English. Web cameras and dongles (mobile internet data) were provided if needed. While the availability of using an online platform meant that carers from metropolitan and regional Victoria could be involved in this study, recruitment was not specifically focused on carers living outside metropolitan cities.We developed START-online by adapting the START program for delivery in Australia using online videoconferencing. The START-online sessions were weekly and covered: education about dementia, behavioural and psychological symptoms of dementia (BPSD), and carer stress; discussion and problem-solving of challenging situations encountered by carers; planning for the future; and relaxation techniques Table . A projeEthics approval for the project was granted by Melbourne Health Human Research Ethics Committee (HREC/16/MH/133). Written informed consent was obtained from participants prior to commencing the program. Following consent, participants provided baseline data and were given the START-online manual. “Zoom”  was used as it was free for participants and easy to use. Project staff assisted with set-up of Zoom, and provided an explanation on its use either in-person or by telephone.START-online was delivered over eight 1-h weekly sessions by psychology graduates (4 years of tertiary study), who received training and weekly supervision by a registered clinical psychologist. In addition to weekly sessions, carers were encouraged to complete between-session tasks, including noting unhelpful thoughts and practicing relaxation techniques. The manual also included help sheets from Alzheimer’s Australia  and information on using Zoom. In order to review the consistency of the sessions and adherence to the protocol, a fidelity assessment was specifically developed for each session for the project Table  was condUpon conclusion of the program, carers completed outcome measures, an evaluation survey either in-person or over the phone with project staff, and were invited to participate in the evaluation focus groups. Invitations for the focus groups were sent via email, followed by two reminders and a follow-up telephone call. This resulted in eight carers participating in three focus groups also conducted via Zoom.A semi-structured focus group topic guide was developed by the research team based on program evaluation principles  with a fOutcome measures for the carers included the (i) Hospital Anxiety and Depression scale (HADS)  which meThe focus groups were audio recorded and transcribed verbatim. All data was exported for coding into QSR NVivo 12 qualitative data management software . Thematic analysis  was used for frequencies and descriptive statistics with non-parametric tests, such as Wilcoxon signed rank tests, used to compare pre- and post-intervention measures.n = 18 started, and n = 16 (80%) completed all eight sessions  to complete the program. While sessions were allocated on a weekly basis, these occurred when it suited the carer. A session was considered “delayed” when > 14 days had passed since the previous session. Delays occurred due to illness, caring responsibilities and work commitments.Fifty people were initially referred and forty-one were screened for eligibility. Twenty carers were enrolled, n = 12, 60%), were not in paid employment , were spouses of the person living with dementia , nominated English as their first language  and had completed secondary school . Their median age was 67.5 years . The carers nominated a median of 82 h per week caring . The majority were recruited from carer support groups (30%), community health services (20%), care providers (15%) and social media (15%). Most lived in metropolitan Melbourne , n = 3 (15%) lived in regional Victoria and n = 2 (10%) lived in regional centres interstate.The majority of carers who commenced the program were women , vascular dementia  and frontotemporal dementia . The median time since diagnosis was 3 years . In terms of dementia stage using the CDR, the majority of were rated as mild  or moderate  stages. Overall, their QOL-AD score was rated as fair-good and did not change over time.For the PLWD, the most common diagnoses were Alzheimer’s disease (n = 18) completed the survey. The responses (Table n = 14 (78%) agreement. Only n = 13 (72%) of participants regarded online access to be as good as in-person while n = 16 (89%) said that overall they were satisfied with the program. The questions relating to the benefit of the program to them as carers were less enthusiastically endorsed. Only n = 12 (67%) felt that START met their support needs. N = 12 (67%) felt it was suitable for the stage of dementia that the person they cared for was at. Nevertheless, overall n = 17 (94%) said they would recommend the program to other carers.All participants who started the program  and one carer participated in a one-to-one telephone interview.Four key themes emerged from the qualitative analysis: overall experience of the program (acceptability); experience of using Zoom (feasibility); perception of START-online in relation to the timing in their carer journey (demand); and carer needs met and not met by START-online program (acceptability and effectiveness).“I mean, I really loved the program, I liked just sort of knowing that there would be someone there every week.., so I found with the START program that was my one, I had to commit. Because you know, I had committed to somebody else, so I’m going to show up and set that one hour aside.” Participant 009, female caring for her mother“…the interaction with your therapist…they were very understanding. They weren’t abrupt, they weren’t misunderstanding. They were just pretty caring in the sense that they were easy to adapt to work with..” Participant 011, male caring for his wifeAll focus group participants enjoyed the program, and reported several benefits, but two also reported dissatisfaction with the content and structured approach. The importance of the interaction with the therapist, having a regular commitment with the therapist, and being able to discuss problems with a therapist who was empathetic and without judgement were reported by all carers.“…I think the main value was…two things, actually. Confirmation in part, of things that I was already doing or thinking, solutions that I was thinking up, so she was giving me confidence, perhaps, um and seemed interested in my thoughts on solving problems, and secondly .. she came up with some ideas which I hadn’t thought of! And I could add them to my repertoire, I think we had quite good discussions about how to approach certain problems.” Participant 022, female caring for her husband“ not only did I have the person, but it motivated me to try to do my part…because I can’t expect everything to come from the tutor (therapist).” Participant 016, female caring for her motherSome carers reported learning new strategies to help them in their caring role, and felt that the program empowered, motivated or reassured them. Carers described the perceived effectiveness of the intervention and discussed the use and intention to continue to use strategies learnt from the program.“So overall it was good but not dramatic”. Participant 012, male caring for his wife“It was a valuable opportunity but it missed the mark…the person delivering it tried hard..we weren’t able to come up with any ideas” Participant 007, male caring for his parentsHowever, two carers felt less positive about the program.“And whilst the relaxation was fantastic, it was literally the last sometimes maybe 2 minutes, sometimes 5 minutes… felt like it should have been a bit more of a main focus.” Participant 009, female caring for her motherMost carers in the focus group also reported aspects of the program that could be improved or described sections and content of the program that they wanted more focus on did not find relevant or useful for them. This highlighted the need for a more individualised approach.“Part of me, and our sessions often went over, and I think a reason for that is there was almost too much structure in the book.” Participant 003, male caring for his wifeI think it was becoming onerous and sometimes tiresome, like eight weeks didn’t come soon enough sometimes…some of the questions were repetitive.” Participant 019, male caring for his parent“Like say we get to a session where we’re addressing something and I’m already quite versed in that particular topic, really, I just want to be able to talk.” Participant 003, male caring for his wife“…there was a lot of repetition of what is dementia and having a run on a day centre giving lectures on dementia,… preaching to the converted.” Participant 021, female caring for her husbandSeveral carers discussed the burden, or perceived amount of effort required to participate in the program, in terms of having to go through the material in the manual, or sessions being too structured.“Oh, I was lucky, the Zoom worked perfectly well, I'm being a bit … slow to develop my computer skills, I found that part perfectly alright.” Participant 005, female caring for her mother“It didn’t start too well, if I remember we had communication problems with Zoom, but, completed it all.” Participant 022, female caring for her husbandThe use of the web-based delivery and interface was explored. Six carers reported positive experiences with the use of the videoconferencing, with all of those surveyed agreeing that being available online was a good way to access the program.“I can work a computer, and it takes less time. I don’t have to spend half an hour or an hour going into places and coming back again. Would cut down at least an hour and a half at least of my time..” Participant 016, female caring for her husband“Well, I did not have to go into town to attend an appointment. I can do it any time. I guess it was safe for both parties,. So from the point of convenience and safety I think and…. Transport needs as well time saving.. it was good.” Participant 019, male caring for his parentMost carers felt the convenience of being able to participate from their own home and saving on travel time made it an accessible program.“I suppose starting with the technology.. I found that fairly awkward ..it was quite disturbing to watch the screen. It was flickering and uh, shaking, and we tried many things to improve it, but without success. So, that side of it wasn't so good.” Participant 007, male caring for his parentsHowever, two carers discussed having technical difficulties.“Yeah I think if you were just starting out with caring, it would be a great resource to use. Because there are all sorts of traps that you fall into when you're just starting out.. This could short-circuit a lot of those sorts of traps.” Participant 007, male caring for his parents“Quite a lot of it is not terribly relevant, is it, once you’re that far down the track?” Participant 004, female caring for her motherSome participants felt that the START-online program would have been most appropriate for carers close to the time of the PLWD receiving the dementia diagnosis as well as the start of their caring journey.“I wouldn’t know, for anybody else’s story and how they’re handling the situation, … I asked for help because I feel like her personality’s changed a little bit.., ..I couldn’t comment on when anyone else would you know, best need that help, it’s just individual.” Participant 013, female caring for her motherParticipants in the focus groups also acknowledged that it was difficult to identify an ideal time to undertake START-online because caring situations and carer needs varied widely.rent rates over time..” Participant 003, male caring for his wife“…maybe a health advisor or health professional is in a better position to know when you might be needing it or something, rather than trying to target a particular period after onset when you think the program should be introduced, because people’s conditions obviously change at diffeOne suggestion was for carers to be screened to determine whether START-online was likely to be beneficial for their situation.“It’s more of having that lifeline, like you just become so isolated, you realise that my mum has two carers a day, she has people she does art with at night, I’m sending someone in that teaches her tech lessons, her world has as much support as could be put in place as possible, and then I’ll think, I’ve not seen anyone for a month.. , I am way more isolated than the actual care recipient. So in that sense I feel that’s why it’s really important, in fact I think it’s critical, carers have to have access to ongoing support based on, depending on what their needs are.” Participant 009, female caring for her mother“It needs the discussion and the reassurances that every carer wants all the time, I’m guessing, needs a human touch and support as well.” Participant 012, male caring for his wife“I think it would be really good if there was some sort of option to keep that going. To have some sort of ongoing contact, maybe just on a needs basis, you know, you could sort of send a message to him or her, and say, um, look I'm really struggling with this, could we have a short Zoom session on that or you know, something like that…. it was delivered over the eight weeks and then it was finished.” Participant 007, male caring for his parentsCarers discussed the isolation they often felt as well as not having the time to look after their own care needs because they prioritised the PLWD needs. Although the START-online program offered some support and strategies for carers, as mentioned above, several carers felt a more individualised approach would be preferable. Participants also expressed that the short-term nature of the program did not fully meet their needs and that they might want to access ongoing support throughout the carer journey.“Flexible times because I'm sure others are just as busy as I am. Could it be an ongoing support for carers?” Participant 005, female caring for her mother“Greater emphasis on carers getting the support they need.” Participant 007, male caring for his parents“Offer advocacy. More fluid approach to counselling and less constrained by manual… This could be done at baseline assessment to understand where carer's knowledge and use of services is to tailor the recommendations and strategies to them.” Participant 009, female caring for her mother.Similar comments were made in response to the question "How could we make START-online better?”Table This study aimed to investigate the acceptability and feasibility of an adaptation of the UK START program to carers in Australia delivered online via Zoom platform. START-online was found to be acceptable, with a high completion rate generally positive feedback about its structure and content—which was standardised and could be delivered consistently by supervised psychology graduates, with limited clinical training. The mode of delivery was also acceptable, with most carers indicating overall positive experiences with Zoom, with some appreciating the practicality of not having to travel, despite some technical difficulties. This suggests that further implementation is feasible. The survey results suggest that carers felt START-online was generalisable and needed, with 97% saying they would recommend the program to other carers. The role of the therapist in delivering START-online was considered important by carers, rather than as an “app” or a web-based program. However, improved screening for inclusion is required, as START-online may be more appropriate for those in the early stages for caring, which might negatively affect feasibility and implementation. In terms of the methodology and quantitative measures used, these appeared feasible, as all carers who finished START-online completed all the measures.Most participants were positive about their experience with START-online, with comments about it “being a lifeline” and therapists being caring. There were also some consistent suggestions for how it could be improved. The program was adapted to better suit carers living in Australia, including modification of the language  and information regarding services, This may have meant that it “lost” some aspects as it as in the same language (English). For example, one carer thought relaxation should come earlier in the program and did not appear to know the program was designed for them to use relaxation between sessions and participants were given the recordings to facilitate this.Some focus group participants suggested that START-online would have been more relevant to them at the early stages of dementia. Sixty-seven percent of those surveyed reported that START-online was at the appropriate stage; however, it is not known which stage this was for the carers who endorsed this response—hence, it remains unclear which stage of caring START-online would be best for. This is unlike the original UK START where most of the carers included were at the early stage of caring. START-online could be offered as a series of modules, rather than an 8-session package, with carers given a choice about the modules that they take, which might enhance acceptability.This study demonstrated that most participants could use the online platform, Zoom, although some had technical difficulties. Although using an online platform meant that both metropolitan and regional carers were potential participants, only 25% of our recruited carers lived outside a metropolitan area. This was primarily due to limited familiarity with Zoom at the time of recruitment (2017–2018) and the need for project staff to assist setting up the software for the participants face-to face. Accordingly, we had to restrict the geographical reach to areas where it was feasible for our project staff to travel. However, people are now more familiar with online platforms due to the COVID-19 pandemic, there is increased potential for reach into rural and remote areas. Regardless of location, participants in this study described START-online as appealing due to the flexibility of access, ease of use, and limited travel required. Having a therapist was deemed particularly valued and moving forwards, the option of having Zoom or face-to-face START, might also improve acceptability. The therapists’ perspectives on this program based in New South Wales are currently under review, by Walter et al. (2022).START-online showed limited differences in quantitative measures, though it was not sufficiently powered to do so. Specifically, there were no reductions in total depression and anxiety. In the UK START study there were reductions, but the control group worsened. In our group of carers, following the end of START-online, there was decreased dysfunctional coping and reduced potentially abusive behaviour. There were significant reductions in potentially abusive behaviour also found in the UK START study in both intervention and control groups , and theSTART-online was, as is the nature of feasibility studies, not designed to be powered for efficacy. In addition, only 8 of the carers who completed the program participated in the focus groups, limiting the generalisability of the qualitative results, as we did not interview the carers who did not complete the program and hence do know what they thought of the program and the detailed reasons why they did not finish it.The COVID-19 pandemic, which occurred after this project concluded, has amplified the need for online delivery of services and support for carers. Given the need to provide accessible and effective treatments for socially isolated carers of people living with dementia, particularly in the post-pandemic era, further examination of the START-online program is warranted. A RCT, with a sufficiently powered sample size using a modified START-online program, including adjustments to make it more acceptable to carers, is needed to determine effectiveness. Further research might also involve carers of people with younger-onset dementia, as they might find the flexible approach of START-online relevant and beneficial.While this pilot study was limited by a small sample and heterogeneity in the disease stage of the PLWD, the findings suggest that START-online was acceptable to, and may improve coping for carers, including those living outside of metropolitan cities who might otherwise be unable to access face-to-face programs. With the recent COVID-19 pandemic necessitating social distancing to avoid infection, interventions such as this one have increasing relevance in the provision of flexible services.Additional file 1.Additional file 2.Additional file 3.