Aristotle's biological writings have happily been the subject of an increasing amount of attention of late. This interest has developed primarily among scholars of ancient philosophy, and has focused in the main on the lessons these treatises might provide for our understanding of central areas of Aristotle's general philosophical thought. In the book before you we present some of the most interesting recent work in this vein, in hopes of stimulating yet wider and deeper attention to this still largely untapped core of Aristotelian writing.

Though the book is addressed primarily to students of Aristotle's philosophy, its extensive attention to the whole of the biology, in matters both of detail and of general purpose and direction, should make it of interest to historians and philosophers of biology as well. We hope this is so, as we think that additional attention from these quarters to Aristotelian biology, and its relations to Aristotelian philosophy, would be beneficial both for Aristotelian studies and for the history and philosophy of biology. As in most other areas, there is much in Aristotle here that remains alive, even vital, for contemporary study. But the focus of this volume is, as we say, on the lessons of Aristotle's biology for our understanding of his philosophy.

The kind of essentialism that has been attributed to Aristotle's biology either identifies form and species, or recognizes individual forms merely as variations from a basic specific form. The essentialist holds in particular that each animal's growth is directed primarily towards the form of the species; that its essence prescribes its form; and that animal form excludes material accidents such as eye color.

These views, although apparently supported by various statements in Aristotle's logic and metaphysics, are directly opposed to some of his most mature and carefully argued theories in biology. Moreover those theories agree closely with one plausible interpretation of the disputed books Metaph. ZH. In this paper I confine myself to the biology; but I would suggest that there is ground here for supporting those who have recently been questioning the ‘essentialism’ in the logic. Here I argue that in the GA Aristotle holds that the animal develops primarily towards the parental likeness, including even non-essential details, while the common form of the species is only a generality which ‘accompanies’ this likeness. In PA he argues for teleology with the question ‘What benefits an animal of this kind?’, not with the question ‘What benefits all animals of this kind?’. He treats species as merely a universal obtained by generalization. While it is true that species-membership may help to explain the features of individuals, this is not because species is an efficient cause of individual formation, but because individuals in like circumstances are advantaged by like features.

Introduction

Some years ago, Jonathan Barnes introduced a discussion of ‘Aristotle's theory of demonstration’ with the following statement:

Barnes argued against three traditional attempts at reconciliation, and provided a radical diagnosis for these failures: the scientific treatises report the tentative explorations of ongoing inquiries, while the Posterior Analytics provides a theory of how to present already acquired knowledge. On this view, the attempt to shed light on the APo. theory of scientific knowledge by a close study of the biological treatises is doomed at the outset.

Barnes has himself drawn back from this conclusion (1981), reviving Friedrich Solmsen's thesis that there is a presyllogistic theory of demonstrative science within APo., which may after all be reflected in the scientific treatises. Both of these papers presuppose that unless one first accounts for the absence, in Aristotle's zoological explanations, of an overtly syllogistic form, one cannot proceed any further in exploring the relationship between his theory of science and his scientific practice.

Introduction

In their contributions to Part I, David Balme and Montgomery Furth have given us reason to think that Aristotle's systematic study of animals might help us to understand those concepts at the center of his metaphysical analysis of substance: form, matter, essence, substratum, kind, universal, differentia, actuality, potentiality, perhaps even nous. Each of the papers in this Part attempts to illustrate that thesis by bringing Aristotle's biological works directly to bear on such central themes of his metaphysics.

The keynote paper of Part IV is a slightly revised version of David Balme's rich and provocative ‘Aristotle's biology was not essentialist’, first published in Archiv für Geschichte der Philosophie in 1980. Balme argues that the essentialist identification of form and species traditionally attributed to Aristotle is not to be found in his biological works. According to GA, an animal's development is ‘primarily towards the parental likeness, including even non-essential details, while the common form of the species is only a generality which “accompanies” this likeness’. Animal form includes material accidents and is to be distinguished from essence, which ‘picks out only those features for which a teleological explanation holds’. Both are to be distinguished from species, which is a generalization over individual composites, over forms as actualized in matter.

The first difficulty in reading Aristotle's biological treatises, as often in reading Aristotle, may well be to decide exactly what their purpose is. They are so factual and so comprehensive that it is easy to mistake them for descriptive information, an animal encyclopaedia, as the ancients regarded them. Modern readers have tried to assimilate them to present-day categories, classifying the HA as natural history, the PA as comparative anatomy, the PN as physiology, the GA as embryology. But this assimilation does not fit. One can test it by looking for the facts about any given animal in HA. Without an index (which ancient readers did not have) the facts can only be found by reading through the whole treatise, for they are distributed all over it; and when found they may seem strangely inadequate. A striking example is the blind mole-rat, aspalax, which Aristotle quotes in the De Anima as an interesting case. He twice describes a dissection of its concealed eyes. But the only other fact that he reports is that it is viviparous – not what kind of animal it is, how many legs, what its coat or feet or tail are like, how it lives, nothing. His aim is clearly not to give a natural history of the mole, but to show how it differs from other animals: it is his only case of sightlessness combined with viviparousness.

The range of Aristotle's investigations in zoology is such that a discussion of his use of empirical methods has to be drastically selective. Yet the need to come to some assessment of his performance in this field is all the more pressing in that it has been subject to such divergent judgments. Some of the most extravagant praise, but also some of the most damning criticisms, have been directed at his empirical researches in zoology.

The massive array of information set out in the main zoological treatises can hardly fail to impress at the very least as a formidable piece of organization. But both Aristotle's sources and his principles of selection raise problems. As we have already noted in connection with his use of dissection, it is often impossible to distinguish Aristotle's personal investigations from those of his assistants, although, given the collaborative nature of the work of the Lyceum, that point is not a fundamental one. It is abundantly clear from repeated references in the text that he and his helpers consulted hunters, fishermen, horse-rearers, pig-breeders, bee-keepers, eel-breeders, doctors, veterinary surgeons, midwives and many others with specialized knowledge of animals. But a second major source of information is what he has read, ranging from Homer and other poets, through Ctesias and Herodotus to many of the Hippocratic authors. In general he is cautious in his evaluations of all this secondary evidence.

In the last chapter of her book Physicalism K. V. Wilkes writes:

This view is developed also by D. W. Hamlyn in the introduction to his Aristotle's De Anima (1968): it certainly has the charm of paradox. The common Greek word nous appears to express our concept of a mind. Aristotle speaks of nous as ‘part of the soul’ and says it differs from other parts in three ways: it is not the concern of the natural scientist, it comes in ‘from outside’, and it is ‘separable’ from the body. If that does not give him a mind–body problem, what would? The fact is that while Aristotle's account of psychological concepts generally, his doctrine that soul and body are related as form to matter or actuality to possibility, is attractively undualistic, when he comes to nous dualism seems to seep back. J. L. Ackrill in Aristotle the Philosopher remarks:

Scientific method in Aristotle's biology

The relation between Aristotle's official account in the Posterior Analytics of the nature of scientific knowledge and of the means by which it is reached and his actual practice in arriving at the results presented in his special scientific writings has long been a topic of considerable study. In the recent history of attempts to account for the discrepancies between Aristotle's theory and his practice, or to explain away the apparent discrepancies, the biological works have been assigned a special role. In his famous and still influential treatment of this problem, Jaeger saw in what he took to be the thoroughgoing empiricism of the biological works the final step in Aristotle's emancipation from the Platonic view of scientific knowledge and method found in the Analytics. Students of Aristotle now agree that Jaeger's general account of Aristotle's ‘progress’ away from Platonism is untenable. But it is still widely supposed that Jaeger was at least right that there are empirical elements in the method practiced in the biological writings to which no role is given in the Analytics.

The chief difficulty that final causes present to modern philosophers lies in reconciling them with what Aristotle calls ‘necessity’, that is the automatic interactions of the physical elements. It is difficult to see, first, how laws of nature can be directed towards goals and still remain ‘necessary’; and, secondly, what could be the author and the means of such direction. The modern cybernetic model, and the concept of elaborate genetic coding, have not altered the problem; they have merely shown that some apparently teleological processes may in fact be necessary outcomes. It is arguable, as we shall see, that in the GA Aristotle himself was moving towards such a position. But there is no sign of it in PA, nor is there any sign in his writings generally that the relationship between finality and necessity could be a difficulty of the sort that we feel.

The novelty in Aristotle's theory was his insistence that finality is within nature: it is part of the natural process, not imposed upon it by an independent agent like Plato's world soul or Demiourgos. This is what allows him to claim that none of his predecessors had recognized the final cause with any clarity. Anaxagoras called his primary cosmological cause ‘Mind’, and for this Aristotle likened him to a lone sober man among drunks; Plato offered cosmic teleological causes in the Timaeus, Philebus and Laws; Xenophon argued for the popular belief in providential guidance of natural phenomena.

Aristotle is often characterized, by both philosophers and evolutionary biologists, as the fountainhead of a typological theory of species that is absolutely inconsistent with evolutionary thinking. D'Arcy Thompson, on the other hand, in his remarkable On Growth and Form, claimed that the idea of using quantitative methods to help understand morphological relationships among animals of different species took root in his mind during his work on Aristotle's biology:

A theory that asserts that species of a genus differ only in the relative magnitudes of their structures sounds very different, and might be thought to be incompatible with, a theory that claims that there are complete discontinuities between one eidos and all others. Can Aristotle consistently have held both these views? He can, and he did. To understand how he did so, one must understand the way in which he used the Academic technical notion of ‘the more and the less’ in his biology.

A longstanding problem concerning Aristotle's philosophy of science is the extent to which there is a serious conflict between the account of scientific explanation and investigation in the Posterior Analytics and the explanations and investigations reported in treatises such as the Historia Animalium, Parts of Animals, and Generation of Animals. I shall not here mount a frontal attack on this question, preferring instead a rearguard action. This will consist of (i) articulating a familiar epistemological distinction between unqualified and sophistic or incidental understanding, which plays a fundamental role in Aristotle's philosophy of science; (ii) relating that distinction to the methodological recommendations of Posterior Analytics 11.14; and (iii) presenting three sorts of evidence from the PA and HA indicating that the zoological works owe a great deal both to the above epistemological distinction and to its methodological implications. The evidence for (iii) will consist of the organization of information found in the HA, the relevance of that organization to the explanations of PA, and the theoretical and practical concern with the way in which lack of an appropriate zoological nomenclature can hamper the achievement of understanding. The evidence points to a much more direct relationship between the APo. and the biology than recent commentators have suggested.

Animals, in Aristotle's view, are paradigm instances of substance-being. We may wonder whether Aristotle began with that conviction and shaped his ontology in the light of it, or arrived at it as a result of what his ontology revealed the nature of substance to be, and that question in turn may be related to our views about when and with what attitude he did his biological work. But whatever we decide to say on these questions, our answers will have to take account of his clear conviction that natural living things are ‘above all substances’.

We should therefore expect that Aristotle thought the most important features of substance to be exemplified in the case of living entities. This need not mean that he claimed that only animals are substances. On the whole, Aristotle was less concerned with the correct identification of a class of entities which are substances than with the proper understanding of the principles and modes of being by virtue of which those entities which we commonly understood to be substantial beings are substantial. He was, we might say, less interested in substances than in substance-being, less concerned with the question of what beings are substances than with the question of what it is to be a substance. But among the beings that Aristotle saw as commonly (and therefore in some sense correctly) understood to exemplify substance-being, animals came first, and those features which metaphysics reveals as characteristic of substance-being should therefore be evident in the being of animals.

In his famous exhortation to biological study in the last chapter of Parts of Animals 1, Aristotle offers his students several reasons for pursuing the study of plants and animals.

While the study of the heavens has the superior objects, he begins, the information about living things is ‘better and more plentiful’, and their study thus ‘take[s] the advantage in knowledge (epistēmē)’ (645a1–2).

This study is also, Aristotle continues, a source of ‘wonder’ and ‘immeasurable pleasures’, since ‘the non-random, the for-something's sake, is present in the works of nature most of all, and the end for which they have been composed or have come to be occupies the place of the beautiful’ (a9, 17, 23–6). The epistēmē that this study of living things offers is an understanding final causes, and the pervasiveness, and perspicuousness, of the final cause among plants and (especially) animals is another source of the biology's value.

In two places in his extant works, in Physics 11.9 and three connected passages of the Parts of Animals 1.1 (639b21–640a10,642a1–13,31–b4) Aristotle introduces and explains his notion of ‘hypothetical necessity’ (anangkē ex hupotheseōs). Judging from this terminology one might think a hypothetical necessity would be anything that is necessary given something else, or something else being assumed to be so (cf. APr. 1.10 30b32–40) – in effect, anything that follows necessarily from something else's being so, but that may not, taken in itself, be necessary at all. But this is not so: the necessity of New York's being north of Princeton given that it is north of New Brunswick and New Brunswick is north of Princeton, is not an example of what Aristotle calls a hypothetical necessity. This is because the hypothesis relatively to which a hypothetical necessity, in Aristotle's usage, is necessary is always a goal posited or set up (hupotethen) as something to be achieved. Hence the necessity in question is always that of a means to some end. A hypothetical necessity, as Aristotle intends the term, is something necessary if some goal is to be attained. Thus, he says, a saw or an axe has to be hard in order to do its job of cutting or splitting, and in order to be hard it has to be made of bronze or iron: hence it is necessary for a thing to be made of bronze or iron if it is to be a saw or an axe, and there must be bronze or iron to hand if one is to carry out the intention to make a saw or an axe.

In this paper I want to explore the application of some of Aristotle's central metaphysical notions to the analysis of living things. Commentators have often remarked that the conceptual pairs of matter / form and potentiality/actuality apply best to the analysis of Aristotle's favorite example, the bronze statue, but fit organic creatures – the true substances – less well. Two distinct problems arise for these more complex cases.

First, it seems impossible to point to something which serves as both matter ‘for’ and matter ‘of’ a living creature, as bronze does for statues. In Physics 1.7 Aristotle tells us that in any change some underlying thing or substratum persists, and it is easy to see that the bronze persists when a statue is molded, the gold continues in the bangle, etc. But what exists before a person, duck, or oak tree comes to be is an embryo, egg, or acorn (cf. Ph. 1.7 190b3–5) – and these surely do not remain in the finished creatures as their matter. This disanalogy is the target of William Charlton's criticism in his commentary on Physics 1 and II:

Introduction

If Aristotle is known for anything it is for his teleology. In the understanding of this issue the biology has proved especially useful, as one might well expect, since the primary subject of teleological explanation for Aristotle is the living thing – its development, structures, and activities.

What, then, is it, according to Aristotle, for a part of a living thing to be for the sake of an end, where that end is explanatory of the part's presence in an organism? And what is it for that part, or that organism, to come to be or to act for the sake of an end, where that end is not consciously aimed at? Earlier interpreters tended to assimilate the general living case to the human case, and they spoke for instance of potential souls and invisible entelechies guiding organic development – of ‘immaterial agencies’ of various sorts. But this, as J. H. Randall, Jr. (1960) pointed out, is to turn the final cause into an efficient cause. More recent interpreters agreed, and went on to speak as if the true causation involved in teleological processes was all at the material level.