INTRODUCTION

In the Analytica Posteriora, Aristotle defines scientific knowledge as knowledge of the reason why. Knowing why something is the case amounts to being able to provide a scientific demonstration (apodeixis), which consists in a valid syllogistic argument in the mode Barbara (i.e., AaB, BaC, ∴ AaC). Such demonstrations typically deduce the necessity of an attribute belonging per se to a certain subject through a middle term that picks out the cause of that necessary relationship. Thus, if formalized in accordance with the recommendations of the Analytica Posteriora, causal explanations (i.e., linguistic expressions that identify the cause of some phenomenon) will constitute scientific demonstrations. However, despite the long tradition of Aristotelian scholarship on this treatise, many details concerning the precise nature and syllogistic structure of demonstration remain enigmatic, and are subject of much controversy.1

In this chapter, I aim to shed light on Aristotle's pivotal discussion of the integration of the four types of causal explanation into the syllogistic framework of demonstration in APo II.11, and specifically on his suggestions on how to formalize teleological explanations. In the first part of this chapter (sections 6.1–6.3), I shall clarify the examples Aristotle provides to illustrate his theoretical remarks about how to formalize causal explanations into the syllogistic structure of scientific demonstration. In particular, I hope to make sense of the teleological example of walking after dinner for the sake of health.

Aristotle appeals in a variety of ways to his theory of natural teleology in order to generate explanations of biological phenomena. At the most basic level, living beings are explained to have the capacities of the soul they have in virtue of those capacities being necessary for the sake of living, and in the case of the more complex and less widespread capacities, in virtue of being necessary for living well. At the more complex level, Aristotle explains that living beings – and also the heavenly bodies – have the bodily parts and features they have for the sake of exercising their vital and essential capacities, or for contributing to the performance of those vital and essential capacities, or because they serve their well-being in some other way.

What unifies these teleological explanations is that they all pick out a function or beneficial end as that for the sake of which some feature is present. In addition, the presence of this function or end is identified as the outcome of the operation of a goal-directed efficient cause (i.e., as being due to the goal-directed actions of the formal nature or soul of a natural being), where this process of coming to be either consists in the realization of a potential for form, or in nature making good use of excess materials.

INTRODUCTION

In his programmatic opening to the Meteorologica (Meteor I.1, 338a20–339a10), Aristotle puts the issues discussed in De Caelo at the center of his science of nature. The study of “the stars ordered according to their upper motion” (Meteor I.1, 338a21–22), and of “the bodily elements, their number and nature, and their change into each other” (Meteor I.1, 338a22–24) is said to follow his examination of the first principles of nature and of natural change in general, but to precede his investigations of sublunary living nature. In accordance with this outline, Aristotle first – in De Caelo book I – argues for the existence of a fifth, heavenly element (i.e., aether) in addition to the familiar four sublunary, changeable ones (i.e., air, water, fire, and earth), and discusses the nature and characteristics of the universe in its entirety (i.e., its size, uniqueness, and eternity). Then, in book II, Aristotle turns to the motions and features of the heavens as a whole, of the individual planets and stars, and lastly of the Earth. Next, in book III, he focuses on the nature and motions of the four sublunary elements, saving his definitions of “weight” and “lightness” associated with these elements for book IV. By engaging with the heavenly phenomena in the first two books and only then turning to the sublunary elements, Aristotle mimics the order of exposition of Plato's Timaeus.

INTRODUCTION

Aristotle's theory of natural teleology applies in particular to living natural substances: their coming to be and existence, their change and development, and many of their differentiations are the result of the goal-directed actions of their formal natures. In the following two chapters, I discuss the role of teleology in the explanations Aristotle provides of the presence, absence, and differentiations of animal parts in De Partibus Animalium.

In Chapter 4, I shall present an analysis of the structure, role, and explanatory of force of the actual explanations recorded in De Partibus Animalium books II–IV; here, in Chapter 3, I shall first outline Aristotle's theory of explanation in biology as introduced in De Partibus Animalium book I. In section 3.1, I sketch the demonstrative character of the science of biology; this will provide some background to the larger scientific context within which Aristotle's use of teleological explanations takes place. In section 3.2, I discuss the notions of teleology that Aristotle employs in his discussion of the standards for explanation in the natural sciences in De Partibus Animalium book I. My aim here is to show that there are two types of teleology underlying these explanations: a primary kind that involves formal natures realizing a preexisting potential for form through conditional necessity, and a secondary kind that involves formal natures using materials that have come to be of material necessity for something good.

INTRODUCTION

Aristotle introduces his investigation of the soul in De Anima as being among the primary kinds of knowledge, on account of both its accuracy and its dealing with better and more wonderful things (DA I.1, 402a1–5). Knowledge of the soul contributes especially to natural philosophy (DA I.1, 402a6–7; cf. DA I.1, 403a27–28), because the soul is “a sort of1 principle of living beings” (DA I.1, 402a8: ἔστι γὰρ οἷον ἀρχὴ τῶν ζῴων) and living nature represents Aristotle's concept of nature in the fullest sense.2 For Aristotle, then, the study of the soul and its embodiment is the starting point of biology,3 and as such forms an important part of his broader investigation into nature.

The issues Aristotle sets out to address in De Anima are, first, the nature and essence of the soul and, second, the soul's attributes – both the ones proper to the soul and the ones living beings have in virtue of having a soul (DA I.1, 402a8–11). This program leads Aristotle, among others, into investigations of the ontological status of the soul and its parts, of the relation between the body and the soul, and of the various capacities of the soul that living beings share. In this chapter, sidestepping many of the difficulties in the interpretation of this treatise, I shall focus rather narrowly on Aristotle's bio-functional analysis of the soul, i.e.

Encomium of Helen

8–14

If, however, it was speech that persuaded her and deceived her soul, it is not difficult to defend her against this too and acquit her of the charge, in the following way. Speech is a powerful master, which accomplishes most divine deeds in the most diminutive and imperceptible body. For it can put an end to fear, take away sorrow, incite joy and augment pity. I will demonstrate that this is so.

Indeed, a demonstration for the listeners that would form their opinion is in order. I consider and call every sort of poetry ‘speech with metre’. Those who listen to it shudder with great fear, and are seized by tearful pity and mournful longing; the soul experiences something personal, through these words, on account of the good or ill fortunes that befall the affairs and bodies of others. But it is time to turn from one point to another.

Through words, inspired incantations bring pleasure and drive away pain. For the power of the incantation, working together with the soul's power of judgement, enchants, persuades and converts it by witchcraft. We know of twin arts, witchcraft and magic, that mislead the soul and deceive the judgement.

So many people have persuaded or do persuade so many others on so many subjects by composing false discourse! Now if everybody had the memory of all past things, awareness of all present things, and foreknowledge of all future things, the same words would not have the same power.

Ion

533d–536d

socrates: This ability of yours to talk well about Homer, which I spoke of just now, is not a skill but a divine force which moves you. It is like the force in the stone which Euripides called Magnesian, but which most people call Heraclean. For indeed this stone not only attracts iron rings themselves but also passes its force on to the rings so that they in their turn can do the same as the stone and attract other rings. Sometimes there is a very long chain of rings and bits of iron, all attached to each other; the force which links them all together comes from that stone. In just this way the Muse herself makes people inspired, and they in turn inspire others, forming a chain of inspiration. For all the good epic poets recite all these fine poems not through skill but because they are inspired. The same goes for the good lyric poets: just as those who celebrate the Corybantic rites are not in their right minds when they dance, so too the lyric poets are not in their right minds when they compose these fine poems; whenever they embark on harmony and rhythm, they act like Bacchants and are possessed. Just as Bacchants, when possessed, draw honey and milk from rivers and are not in their right minds, so the lyric poets' soul does this too, as they themselves say.