Aristotle's Philosophy of Biology
James G. Lennox
Cambridge University Press, 2001

"Animals are unities of matter and form - souls are simply forms (read 'functional capacities') of animate bodies. Aristotle's teleology is based on recognition that animate bodies are structured as they are, and develop as they do, in order to perform the functions that make up an animal's life." (LENNOX, p. xx) [PSA: I would say activities, not functions.]

"Every natural object has a material nature, certainly; but they owe their distinctive modes of being and acting to their *formal* natures." (LENNOX, p. xxi)

"Ultimately, the explanation for these differences is teleological - the peculiar legs and beak of the spoonbill or the curlew ... develop for the sake of their ways of life, their bioi.... [T]he package which constitutes a distinct bird form precisely adapts it to its way of life - specifying 'what it is to be a spoonbill' is explaining how its differentiae are precisely those needed to live as it does." (LENNOX, p. 129)

"[A]t least with regard to living things, the 'essence/accident' distinction is a distinction between those features which are required by the kind of life an animal lives and those which aren't.... The stress is constantly on the way in which the differentiation of a feature is related to the possessor's life." (LENNOX, p. 175)

"[I]f the feature is neither part of the kind's nature nor proper to each kind, then it neither came to be nor is for the sake of anything - nor should it be included in an account of the animal's being." (LENNOX, p. 176) [citing GA V.i 778a29-35]

"[T]he 'formal unity' of a number of animals turns on their having just the proper conformation of each part, and just the proper range of activities, for the life they have to live in a specific environment. This will involve their having a fully coordinated set of structures and activities suited to that life. Thus, while individuals of one form of a kind may differ with respect to one affection of one organ only by degree (or even not at all) from the individuals of another form of that kind, the overall unity of their differentiae will suit them to their life and no other, and distinguish them from the individuals of other forms suited to other lives in different environments." (LENNOX, p. 177) [PSA: this is also true regarding both the "parts" of the human soul and human capacities, technai, etc.; cf. DEPEW-1995.]

"[A]t each level there will be an organization among the allowable ranges for each feature of each differentia which is essential to an animal's life, particularly its mode of feeding, cooling itself, and rearing its young. [fn40: Cf. the use of the concept of the more and the less with respect to psychological and physiological states at HA VIII.1 588a25-b2)." (LENNOX, p. 178)

In his paper "Material and Formal Natures in Aristotle's De Partibus Animalium", Lennox makes "a study of the *interaction* of formal and material natures in living things"; the following notes pertain to that paper:

"Given Aristotle's insistence that '... form has a better claim than the matter to be called nature' (193b7-8; cf. PA I.1 640b28-29), one might expect him to argue that, as far as possible, the natural scientist should study the form of his subjects independently of their matter. Yet he consistently stresses the importance of the scientist studying both together (Ph II.2 194a12-b15, PA I.1 641a15-32, DA I.1 403b1-19, Metaphysics Delta 1 1025b31-1026a7, Zeta 11 1037a10-20)." (LENNOX, p. 182)

Lennox makes two related arguments. First, that "the formal nature is a goal-directed agent, the actions of which are active, selective and informative. By calling its actions *selective* I mean that given a certain material nature, each formal nature determines a *non-random* and *distinctive* realization for that material." Second, that "the actions of a substance's formal nature are severely constrained by its material nature." (LENNOX, p. 183)

"If functionalism is described simply as the view that biological structures are only contingently related to their functions, Aristotle cannot be a simple functionalist." (LENNOX, p. 183)

"[T]here are certain features of living things that *are* sufficiently explained by reference to material natures; and there are certain material facts about certain kinds of animals that are as *explanatorily primitive* as are other facts about their living functions." (LENNOX, p. 183)

"Animals have a material nature (640b28-29, 641a26), and a formal nature (640b27), and the latter is eventually identified with nature understood as an animal's substantial being (641a27). Understood in this way, the formal nature is claimed to be both the mover and goal of living things, and is eventually identified with their soul." (LENNOX, p. 185) [PSA: In applying this discussion of material natures to the realm of action, we should keep keep firmly in mind Furth's treatment of material and form in his book Substance, Form and Psyche.]

"PA I.1, then, endorses the distinction, argued for in Physics II.2, between two natures, one material and the other formal, this latter variously identified with an animal's substantial being, the source of its movement, its goal, and its soul. [fn9: Aristotle's point is, of course, that the soul of the entire organism, as its form, is that for the sake of which the body, its parts, and their particular functions, are present. In PA II-IV, the formal nature functions, it seems, principally as a goal-directed *efficient* cause, rather than as a goal. This follows from the fact that the nature under consideration always acts for the sake of something. This doesn't rule out, of course, its also being a goal (see notes 14 and 17 below). The formal nature of an organism in this sense refers to those dispositions to organize the distibutions and assimilation of nutrients [PSA: and, I would add, information] in the way that maintains the organism." (LENNOX, p. 185) [fn14: "I have already discussed PA I.1 641a27-28, where nature spoken of as substantial being is said to be both nature *as mover* and nature as goal. In very similar words, DA II.4 415b9-12, 415b22-416a9 argues that soul is source and cause in the sense of substantial being, that for the sake of which, *and origin of movement*, and then goes on to make it clear that insofar as the capacity to nourish is an aspect of soul, an organism's growth and nourishment is due to the activation of these capacities. Thus while it is clear that the language to characterize nature's actions is borrowed metaphorically from human craftsmanship, the idea that formal natures (souls) are agents is not to be taken metaphorically."] [fn17: "It is plausible, however, that, since the actions of the nutritional soul not only support all other parts and functions of the organism, but are self-supporting as well, they are at least partly constitutive of the end for the sake of which they are directed."]

"Not long after developing the idea that an animal's formal nature is, in one of its guises, the goal of an animal's various structures and functions, Aristotle discusses a distinct type of necessity that materials possess relative to goals: '[T]he third sort of necessity is present in those things which come to be; for we say that nutrients are necessary not in virtue of any of the other modes of necessity, but because it is not possible to be without nutrients. This necessity is, as it were, hypothetical.' (642a7-9) In this passage, an animal's parts and whole body are said 'to be for the sake of something', and its nourishment *necessary for* the continued existence of organisms. The material nature of an animal is, in this sense, a conditionally necessary nature - *if* there is to be an animal of a certain kind, it *must* (i.e., *cannot not*) have the proper nutrients.... Matter is, then, necessitated to be in a certain way, given a certain end; but it does not necessitate that end. If the formal nature of an ax is its functional ability to cut, hypothetical necessity takes the form of functional constraints on ax-matter: the function of an ax requires matter of an appropriate dispositional nature, shaped in an appropriate way. Matter, in this case, is the necessitated, form the necessitating, nature." (LENNOX, p. 186) [PSA: Consider how this applies to the ergon of the human being, e.g., is arete necessary in this way for a person to live well and act well? Here the dispositional nature is a hexis: it is not possible to take ethical action without *some* hexis of character.]

"That there is, in addition to conditional necessity, a *pre-conditional* necessity dependent on an animal's material nature is suggested in an enigmatic passage at the close of PA I.1, in which two sorts of necessity involved in respiration are discussed. '... necessity sometimes signifies that if one thing is to be that for the sake of which, it is necessary that other things obtain, and sometimes that things are a certain way in accordance with their characters and natures. (642a33-35) The first necessity mentioned here appears to be that required by a goal. The second resides in the character and nature of things, and is not merely conditional on a goal. PA III.2 provides ample evidence that this is, at least in part, a necessity rooted in the material nature of an animal, which constrains, and perhaps acts independently of, the actions of its formal nature." (LENNOX, p. 187) [PSA: Ethical examples could include health and wealth as preconditions of arete, praxis, and eudaimonia.]

"What, then, does Aristotle's praactice suggest is involved in knowing an organism's material nature? First, Aristotle uses the term to refer to the material nature common to different organic structures.... Each of these non-uniform parts must be constituted of an earthen uniform part, because of the dispositional properties required for the varied tasks they perform. Second, to know the material nature of a part, in *that* sense, is to know *that* such material is present, and to *explain* its presence by appeal to conditional necessity.... Third, in a significant number of explanations in PA II-IV ... the amount and kind of elementally distinct materials available in the nutritional make-up of animals is taken as a given. I have argued that this evidences a *preconditional* necessity that places *fundamental material constraints* on the actions of the formal nature." (LENNOX, pp. 195-196) [PSA: here again, consider all of this in the light of FURTH.]

"[F]rom premises which identify the ... function of the organ, and the dispositional properties required to perform that function, it is established that the organ must be made of material with that dispositional property.... Second, from *that* conclusion, and a premise that notes that a certain uniform part ... has the relevant dispositional property..., it is concluded that the organ must be made of that ... uniform part." (LENNOX, p. 197) [PSA: Similar reasoning can be applied to roles in society and to the internal roles of parts of psuche.]

Citing passages in which Aristotle discusses the functional role of the epiglottis, Lennos notes: "Such passages as these provide further insight into the claim that the natural philosopher should study both the matter and the form, and the form insofar as it is that for the sake of which the item to be understood exists (cf. Physics II.2 194b7-15; DA I.1 403b1-12). He must study the matter if he wishes to understand why a non-uniform part is constituted of a certain sort of material, for its being constituted of a certain material limits its changes and actions, permitting it to act in certain ways and not others. Further, even in the premises of such explanations there are appeals to the dispositional properties of the uniform parts in question, properties rooted in their elemental nature." (LENNOX, pp. 198-199)

"[A]ttempting to preserve the unity of the composite by strongly identifying matter and form in the actual composite may have trouble accommodating the dynamic interaction of material and formal natures in the explanations we have looked at, as well as the extensive role played by material natures in those explanations. Conversely, downplaying the importance of material natures in Aristotle's science can be accomplished only by ignoring a sizable portion of the biological corpus." (LENNOX, p. 200) [PSA: Similar considerations might apply to ethical inquiry and reflection regarding the composite nature of human beings, e.g., in EN X.]

In his paper "Nature Does Nothing in Vain", Lennox explores a principle defined in De Progressu Animalium 704b12-18: "nature does nothing in vain, but always, given the possibilities, does what is best for the substantial being [ousia] of each kind of animal." Fundamentally, Lennox argues that according to Aristotle "natural objects ... have propensities to behave in kind-specific ways, but can be prevented by abnormal external circumstances from doing so. Thus, on a variety of occasions, 'for the most part' is explained by noting that things happen in accordance with their natures *unless something prevents them from doing so*." (LENNOX, p. 207) [PSA: In his ethical works, Aristotle also invokes the proviso 'if nothing impedes' - yet it's not clear what these impediments are: are they always external, or can they also be internal? See also Physics 199b15-18.]

"[T]he range of possibilities is represented by the generic features of the more extensive kind to which an animal belongs. Each formal nature does what is best, within that range of possibilities represented by its wider kind(s). Among these 'generic' restrictions are those related to the kinds and quantities of materials the formal nature is provided to work with in achieving the good." (LENNOX, p. 207) 

A second formulation of the "nature does nothing in vain" principle is found in GA V.8 788b20-25: "nature neither falls short nor produces anything pointless among the possibilities." Lennox explains the "falls short" idea as follows: "In the teleological conception os nature Aristotle defends, biological processes have proper completions or ends, and one can evaluate such processes in accordance with that standard." (LENNOX, p. 208)

"In the crafts, the artist works on his material by means of his manipulation of the tools of his trade. But the movements of those tools are not random: they are guided by the principles of the craft Aristotle identifies as the form of that craft's product. [fn9: See Balme 1972, 95, 153. Balme argues convincingly that Aristotle is comparing the *craft* with the parent's *nature* or form, not the craftsman with the parent. Balme also reads Physics 199b28, 'The art too does not deliberate,' as *literally* about the art and not about the craftsman.] The arts of medicine or architecture exist, as knowledge of what it is to be healthy or a good dwelling, in the craftsman's soul (cf. Metaphysics Zet 7 1033b1ff; GA I.22 730b16; PA I.1 639b16-21)." (LENNOX, p. 231)

With reference to Gotthelf's famous paper, Lennox notes "I have doubts that Aristotle held that reproduction involves '*an* irreducible potential for form.' The relevant texts suggest an integrated *series* of potentials, the crucial factor being the formal pattern possessed by the series." (LENNOX, p. 248, fn41) [PSA: See FURTH, pp. 147ff., as well as EVANS, pp. 42-45.]

"[I]n his ethical writings, chance plays a crucial role in determining responsibility for an action." (LENNOX, p. 250)

"It seems plausible to suppose that there will be processes - just those Aristotle says are by chance - which achieve beneficial results and yet are not goal directed.... support for this view deries from the Nicomachean Ethics. Ross has pointed out that EN 1111a5, 1135b12 [PSA: this is actually one of the common books, i.e., EE], and EE 1225b2 describe actions as for the sake of some result even though that result was not a goal of the agent." (LENNOX, p. 257)

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