Unit 5 | Applications: the Soul in Animal Generation

5.1 | Soul as the Form of a Living Body

Recall
Aristotle’s answer to the central ontological question, “what is substance?” or “what is the substance of x?”, is that substance is a cause of being, understood here as form in its role as efficient and/or final cause of x.
Question
How does this this conception of substance as both form and cause of being influence Aristotle’s approach to natural science, in particular, his zoology or science of animal life?

Big Picture: Aristotle’s Zoological Works

Work Contents
Historia Animalium Organized presentation of facts (“thats”) about animal kinds
De Anima Account of “nature and essence” of soul.
Parva Naturalia Shorter works on attributes “common to soul and body”, incl.:
De Sensu: Sensation and sensible objects
De Memoria: Memory and recollection
De Somno: Sleep
De Insomniis: Dreams
De Div.: Divination in sleep
De Longitudine Vitae: On the length and shortness of life
De Juventute: On youth and old age
De Partibus Animalium Explains soul as final cause of animal body
De Generatione Animalium Explains soul as efficient cause of animal body
De Incessu Animalium Account of types of animal motion
De Motu Animalium Account of psychological causes of animal motion

The Project of De Anima

Aim
To determine the essence and attributes of soul.

DA 1.1, 402a1–8 (Shields tr.)

We count cognition among the fine and honourable things, and suppose that one kind of cognition is finer and more honourable than another owing to its precision or because of its having better and more marvellous objects; and for both these reasons we may reasonably place an inquiry into the soul into the premier class of study. It also seems that research into the soul contributes greatly to truth in general, and most especially to truth about nature. For the soul is a sort of first principle of animals. We aim to consider and ascertain its nature and essence, and then its properties, of which some seem to be affections peculiar to the soul itself, while others belong to animals as well because of the soul.

Method
By studying both the form and matter of living things, as a natural scientist would!

DA 1.1, 402b16–29 (Shields tr.)

And it would seem that all the affections of the soul involve the body—anger, gentleness, fear, pity, courage, as well as joy, and loving and hating. For at the same time as these, the body is affected in some way. This is shown by the fact that sometimes, even though strong and evident affections are present, we are not provoked or made afraid, while at other times we are moved by something small and obscure, whenever the body is agitated and in the condition it is in when angry. This is even clearer from the fact that sometimes though nothing frightful is present, people come to have the affections of a frightened person.

If this is so, it is clear that the affections are accounts in matter. Consequently, definitions will be of this sort, for example: ‘being angry is (1) a sort of motion (2) of a body of such a sort, or of a part or capacity of a body, (3) brought about by this (4) for the sake of that.’ And for these reasons, a consideration of the soul, either all souls or this sort of soul, is already in the province of the natural scientist.

Aristotle’s Definition of Soul in De Anima 2

Aristotle’s postive account of soul begins in Book 2 of De Anima, which begins somewhat predictably but marks a radical change in the focus of psychological investigation. In summary:

De Anima 2.1
Soul is the form and first actuality of an organic body, a body having the potential for life.
De Anima 2.2
This can serve only as an “outline” account of soul, since “living is said in many ways”.
De Anima 2.3
To formulate a “scientific” definition of soul—one that explains how soul operates as the cause of life—we must turn our attention to the principal capacities of soul, including nutrition, reproduction, perception, locomotion, and thought.

The Outline Account of Soul in De Anima 2.1

DA 2.1, 412a 5–22 (Shields tr.)

We say that among the things that exist one kind is substance, and that one sort is substance as matter, which is not in its own right some this; another is shape and form, in accordance with which it is already called some this; and the third is what comes from these. Matter is potentiality, while form is actuality; and actuality is spoken of in two ways, first as knowledge is, and second as contemplating is.

Bodies seem most of all to be substances, and among these, natural bodies, since these are the principles of the others. Among natural bodies, some have life and some do not have it. By ‘life’ we mean that which has through itself nourishment, growth, and decay.

It would follow that every natural body having life is a substance, and a substance as a compound. But since it is also a body of this sort-for it has life-the soul could not be a body; for the body is not among those things said of a subject, but rather is spoken of as a subject and as matter. It is necessary, then, that the soul is a substance as the form of a natural body which has life in potentiality. But substance is actuality; hence, the soul will be an actuality of a body of such a sort.

Two refinements:

  1. Soul is the actuality in the way knowledge is (= first actuality) rather than the way contemplating is (= second actuality):

DA 2.1, 412a23–29 (Shields tr.)

Actuality is spoken of in two ways, first as knowledge is, and second as contemplating is. Evidently, then, the soul is actuality as knowledge is. For both sleeping and waking depend upon the soul’s being present; and as waking is analogous to contemplating, sleeping is analogous to having knowledge without exercising it. And in the same individual knowledge is prior in generation. Hence, the soul is the first actuality of a natural body which has life in potentiality.

  1. A body having the potential for life is an organic (functionally organized) body:

DA 2.1, 412b1–6 (Shields tr.)

This sort of body would be one which is organic. And even the parts of plants are organs, although altogether simple ones. For example, the leaf is a shelter of the outer covering, and the outer covering of the fruit; and the roots are analogous to the mouth, since both draw in nourishment. Hence, if it is necessary to say something which is common to every soul, it would be that the soul is the first actuality of an organic natural body.

  • A Complication: the “Ackrill Problem”

    • To be the material cause of a process of generation, the body must be capable of receiving contrary forms.

    • According to DA 2.1, however, the body seems to be necessarily enformed with soul; a dead body, or a body (or body part) lacking soul is a body only homonymously:

      DA 2.1, 412b25–27 (Shields tr.)

      The body which has cast off its soul is not a being which is potentially such as to be alive; this is rather the one that has soul. The seed, however, and the fruit, is such a body (= a body potentially such as to be alive?) in potentiality.

    • How, then, can the body be the matter for soul?

The Homonymy of Life in De Anima 2.2

The account of soul offered in DA 2.1 is however only an “outline” or “general” account of soul, not a scientific definition specifying its essence. Why?

De Anima 2.2, 413a11–20 (Shields tr.)

Because what is sure and better known as conforming to reason comes to be from what is unsure but more apparent, one must try to proceed anew in this way concerning the soul. For it is not only necessary that a defining account make clear the that, which is what most definitions state, but it must also contain and make manifest the cause. As things are, statements of definitions are like conclusions. For example: ‘what is squaring? It is an equilateral rectangle being equal to an oblong figure.’ But this sort of definition is an account of the conclusion: the one who states that squaring is the discovery of a mean states the cause of the matter.

To see what Aristotle has in mind here, we need to appreciate a difficulty for the science of soul that Aristotle raised back in DA 1.1:

DA 1.1, 402b5–8 (Shields tr.)

And one must take care not to overlook the question of whether

  • there is one account of soul, as there is one account of animal,

or whether

  • there is a different account for each type of soul, for example, of horse, of dog, of man, of god, while the universal animal is either nothing or is posterior to these;

and it would be the same if any other common thing were being predicated.

In DA 2.2, Aristotle offers reason for thinking that “there is a different account of each type of soul”, namely that living is said in many ways:

DA 2.2, 413a21–25 (Shields tr.)

We say, then, taking up the beginning of the inquiry, that what is ensouled is distinguished from what is not ensouled by living. But living is spoken of in several ways. And should even one of these belong to something, we say that it is alive: reason, perception, motion and rest with respect to place, and further the motion in relation to nourishment, decay, and growth.

Specifically:

Nutrition (Growth, Decay, Reproduction)
Belongs to everything that is said to live, including plants and animals.
Perception
Belongs to animals but not to plants.
Locomotion
Belongs to some animals.
Reason
Belongs to apparently one kind of animal: humans.

On the assumption that soul is the cause of life in living things: how can there be a single account of soul, given how many different ways living is spoken of?

The Unity of Psychology: De Anima 2.3

Aristotle showed in DA 2.2 that no univocal definition (of the sort given in DA 2.1) of soul could capture its role as the cause of life in the many ways in which living things are said to live. Instead, we need to study the soul of each kind of living thing individually:

DA 2.3, 414b25–28 (Shields tr.)

For this reason, it is ludicrous to seek a common account in these cases, or in other cases, an account which is not peculiar to anything which exists, and which does not correspond to any proper and indivisible species, while neglecting what is of this sort. Consequently, one must ask individually what the soul of each is, for example, what the soul of a plant is, and what the soul of a man or a beast is.

This does not mean, however, that there is not unified science of psychology, as opposed to a set of unrelated sciences of botany, zoology, and anthropology. To the contrary, there is a systematic relation among the capacities of soul present in plants, animals, and humans:

DA 2.3, 414b29–415a13 (Shields tr.)

What holds in the case of the soul is very close to what holds concerning figures: for in the case of both figures and ensouled things, what is prior is always present potentially in what follows in a series—for example, the triangle in the square, and the nutritive faculty in the perceptual faculty. One must investigate the reason why they are thus in a series.

  • For the percepual faculty is not without the nutritive, though the nutritive faculty is separated from the perceptual in plants.

  • Again, without touch, none of the other senses are present, though touch is present without the others; for many animals have neither sight nor hearing nor a sense of smell.

  • Also, among things capable of perceiving, some have motion in respect of place, while others do not.

  • Lastly, and most rarely, some have reasoning and understanding. For among perishable things, to those to which reasoning belongs all the remaining capacities also belong, though it is not the case that reasoning belongs to each of those with each of the others. Rather, imagination does not belong to some, while others live by this alone.

A different account will deal with theoretical reason.

Represented schematically:

The upshot?
“The account of each of these [sc. capacities of soul] will also be the most appropriate account of the soul [itself]” (415a14–15).

5.2 | Closer to a Scientific Account of Soul

Our discussion of De Anima 2 left off with Aristotle on his way to a significant conclusion: the proper subject of the science of soul is not the soul itself but its constituent capacities — including the capcities for nutrition, reproduction, locomotion, and thought.

How does he arrive at this conclusion?

The Unity of Psychology

Aristotle showed in DA 2.2 that no univocal definition (of the sort given in DA 2.1) of soul could capture its role as the cause of life in the many ways in which living things are said to live. Instead, we need to study the soul of each kind of living thing individually:

DA 2.3, 414b25–28 (Shields tr.)

For this reason, it is ludicrous to seek a common account in these cases, or in other cases, an account which is not peculiar to anything which exists, and which does not correspond to any proper and indivisible species, while neglecting what is of this sort. Consequently, one must ask individually what the soul of each is, for example, what the soul of a plant is, and what the soul of a man or a beast is.

This does not mean, however, that there is not unified science of psychology, as opposed to a set of unrelated sciences of botany, zoology, and anthropology. To the contrary, there is a systematic relation among the capacities of soul present in plants, animals, and humans:

DA 2.3, 414b29–415a13 (Shields tr.)

What holds in the case of the soul is very close to what holds concerning figures: for in the case of both figures and ensouled things, what is prior is always present potentially in what follows in a series—for example, the triangle in the square, and the nutritive faculty in the perceptual faculty. One must investigate the reason why they are thus in a series.

  • For the percepual faculty is not without the nutritive, though the nutritive faculty is separated from the perceptual in plants.

  • Again, without touch, none of the other senses are present, though touch is present without the others; for many animals have neither sight nor hearing nor a sense of smell.

  • Also, among things capable of perceiving, some have motion in respect of place, while others do not.

  • Lastly, and most rarely, some have reasoning and understanding. For among perishable things, to those to which reasoning belongs all the remaining capacities also belong, though it is not the case that reasoning belongs to each of those with each of the others. Rather, imagination does not belong to some, while others live by this alone.

A different account will deal with theoretical reason.

Represented schematically:

Therefore
“The account of each of these [sc. capacities of soul] will also be the most appropriate account of the soul [itself]” (415a14–15).

Consequences of this Conclusion

Aristotle has defended the unity of psychology—i.e., the idea that there is a science of soul, understood as a cause of living, over and above the sciences of (e.g.) human life (anthropology), animal life (zoology), and plant life (botany)—by arguing that:

  1. Psychological capcities can be shared by psychological kinds; and that

  2. Psychological capacities exhibit regular patterns of ontological dependence across psychological kinds.

Two important consequences follow from this conclusion.

The Soul Operates as Cause of Life Activities in Various Ways

De Anima 2.4, 415b8–28 (Shields tr.)

The soul is the cause and principle of the living body. As these things are spoken of in many ways, so the soul is spoken of as a cause in the three of the ways delineated: for the soul is a cause (1) as the source of motion, (2) as that for the sake of which, and (3) as the substance of ensouled bodies.

  • That it is a cause as substance is clear: for substance is the cause of being for all things, and living is being for living things, while the cause and principle of living is the soul. Further, actuality is the logos of that which is potentially.

  • It is evident that the soul is a cause as that for the sake of which: just as reason acts for the sake of something, in the same way nature does so as well; and this is its end. And in living beings the soul is naturally such a thing. For all ensouled bodies are organs of the soul—just as it is for the bodies of animals, so is it for the bodies of plants—since they are for the sake of the soul. ‘That for the sake of which’ is spoken of in two ways: that on account of which and that for which.

  • Moreover, the soul is also that from which motion in respect of place first arises, though this capacity does not belong to all living things. There are also alteration and growth in virtue of the soul; for perception seems to be a sort of alteration, and nothing perceives which does not partake of the soul. The same holds for both growth and decay; for nothing which is not nourished decays or grows naturally, and nothing is nourished which does not have a share of life.

This consequence brings into clear focus exactly why a generic account of soul would fail to disclose the way in which soul causes living things to live: namely because, depending on the kind of life (or life activity) in question, soul operates as cause in different ways.

The Dependencies Among Psychological Capacities Stand in Need of Explanation

This is a consequence Aristotle acknowledges several times in De Anima 2:

DA 2.2 413b4–10 (Shields tr.)

Being alive, then, belongs to living things because of this principle, but something is an animal primarily because of perception. For even those things which do not move or change place, but which have perception, we call animals and not merely alive. The primary form of perception which belongs to all animals is touch. But just as the nutritive capacity can be separated from touch and from the whole of perception, so touch can be separated from the other senses. By nutritive we mean the sort of part of the soul of which even plants have a share. But all animals evidently have the sense of touch. The reason why both of these turn out to be the case we shall state later.

DA 2.2, 413b27–414a4 (Shields tr.)

It is evident from these things, though, that the remaining parts of the soul are not separable, as some assert. That they differ in account, however, is evident; for what it is to be the perceptual faculty is different from what it is to be the faculty of belief, if indeed perceiving differs from believing, and so on for each of the other faculties mentioned. Further, all of these belong to some animals, and som of them to others, and only one to still others. And this will provide a differentiation among animals. It is necessary to investigate the reason why later. Almost the same thing holds for the senses: for some animals have them all, others have some of them, and others have one, the most necessary, touch.

DA 2.3, 414b33–415a1 (Shields tr.)

One must investigate the reason why they are thus in a series.

Explaining the Serial Dependencies Among Psychological Capacities

Commentators usually look for the promised explanation in DA 3.12–13, where, among other things, Aristotle accounts for the presence of capacities in different psychological kinds by appeal to hypothetical necessity:

  • The nutritive soul is necessary for all living things to grow and reach (reproductive) maturity.

  • Perception is not necessary for plants, but for animals it is, since without the capacity to perceive:

    • Animals could not acquire food,

    • Nor could they achieve “the goal (telos) that is the function (ergon) of their nature”,

    • Nor could rational animals acquire “a discriminating mind” (nous kritikos).

  • Not all of the senses are necessary for every kind of animal, since only animals who need locomotion in order to find food and avoid danger require the distance senses.

  • For these “roaming” animals, moreover, these distance senses are present not only for the sake of being (to einai) and survival (sotēria), but also for the sake of well-being (to eu).

Question
How does this answer the question of (e.g.) why all perceivers are also self-nourishers?

A Clue to Aristotle’s Strategy

De Anima 2.4, 415a23–b7 (RFH tr.)

For the nutritive soul belongs also to the others, and is the primary and most common capacity of soul in respect of which living belongs to all. (Its functions are reproducing and [in general] using food.) For the most natural function for living things – those that are complete and not maimed or have spontaneous generation – is for it to produce another like itself, an animal an animal, a plant a plant, so that they may share as much as possible in the eternal and divine. For all strive for that, and do whatever they do by nature for the sake of that. (And that for the sake of which is double: on the one hand that of which, on the other that for which.) So, since it cannot share in the eternal and divine in continuity, on account of the inability of any perishable thing to persist one and the same in number, each shares in it as much as it can partake, some more, some less; and not it but something like it persists, not one in number, but one in species.

Question
What makes it true to say that all living things do everything they do by nature for the sake of sharing as much as possible in the eternal and divine?
Possible Answer
The end for whose sake living things are endowed with the psychological capacities they naturally have is the activity that represents the best available means for that living thing to participate in the eternal and divine:
  • For sterile or spontaneously generated animals (non-reproducers), that activity is nutrition and self-preservation.

  • For the vast majority of fertile living things, that activity is reproduction, or eternal persistence in kind.

  • For rational living things, that activity is theoretical contemplation (see EN 10.6–8).

Robert Howton
Robert Howton
Assistant Professor of Philosophy

I am Assistant Professor of Philosophy at Koç University, Istanbul, specializing in ancient Greek and Roman philosophy and the philosophy of perception.