Throughout Aristotle’s De Anima, a theoretical relationship between soul and body is gradually developed. In this paper, I will explain how Aristotle characterizes this relationship, as well as the compatibility of his view with the concept of the separability of soul. In doing so, it is also necessary to adequately describe Aristotle’s definition of soul, which evolves throughout the chapters.
In book one of De Anima, Aristotle offers a general account of the soul, suggesting that without the body, the soul is unable to act or be affected. He maintains that affections of the soul (i.e. emotion, gentleness, fear, pity, confidence, joy, loving, and hating), both affect the body and seem to require a body – “The affections of the soul are, insofar as they are affections of the soul, inseparable from the natural matter of animals [i.e. bodies]” (403b). Moreover, Aristotle conveys that it would be false to attribute motions, such as conditions in which we feel “moved” in a certain way (i.e. anger, pain, enjoyment), exclusively to the capacities of the soul. He claims that it would be wrong to say that the soul is angry, for instance, in that saying this would be like “saying that the soul weaves or builds houses” (408b). It is necessary, then, to attribute motion and the changes which follow from motion to the broader “human being,” rather than the soul. In other words, the human being is affected by motions, and does so by the soul. Motion, according to Aristotle, can either begin from the soul or reach as far as the soul, but motion is not exclusively contained within the soul nor is exclusively an action of the soul. For instance, Aristotle claims that perception is one of those things which “reaches as far as the soul,” while recollection “begins from the soul and extends itself outward” to the motions of the sense-organs within the body (408b). Both perception and recollection, then, ultimately rely on the sense-organs of the body, but also affect and are affected by the soul. It seems evident from this account that Aristotle views the soul and the body as two aspects of a unified thing, in that they work together (that is, they rely on the presence of one another) in order to create and sustain motion. This relationship is further examined within books two and three of De Anima.
Aristotle, in Book two, introduces the concepts of actuality and potentiality in terms of clarifying a soul-body relationship. Matter is the potentiality to be a determinate thing, given the addition of form. Form, meanwhile, is actuality, which is defined as “the state of knowing or the activity of attending to what one knows” (412a). Given this addition, a natural (living) body can be created – a compound of form and matter. In other words, a natural living body is necessarily the combination of both form and matter, or of potentiality and actuality. In total, there are three sorts of substances – matter, “shape” or form, and the compound of form and matter. Matter is not a “this” (a “this” is a determinate thing, such as a person or a statue), in its own right, while form is what can make matter a “this.” Regarding natural bodies which are also living, “life” is said of them as a subject – but, as Aristotle states, “the body [is substance] as subject and matter is not said of a subject” (412a). If what is said of a subject is, indeed, form, it follows that a body’s life, being the “soul,” is substance as form, or actuality. Aristotle draws the conclusion, that soul as substance will be the actuality of the natural (living) body.
Actuality, as defined previously, can be spoken of in two ways – the state of knowing, and the activity of attending to what one knows. Aristotle claims that the soul falls into the first grade of actuality. In an instance provided in De Anima, the living thing requires a soul both during sleep and in being awake. Being awake corresponds to attending to what one knows and being asleep corresponds to the state of “inactive knowing” (412a). Having knowledge, or the state of knowing, is a necessary prerequisite of sort for the fulfillment of the second grade of actuality, which is attending to what one knows or exercising that knowledge. Since a living thing requires a soul both in sleep and in being awake, and since this first grade of actuality precedes the second, the soul must be the first. Aristotle concludes, “the soul is the first actuality of a natural body that is potentially alive.” This definition of soul is consistent in that it maintains the previous requirements, but specifies the grade (or kind) of actuality of the soul.
Aristotle moves forward in specifying the kind of natural body that is “potentially alive.” It is an organic natural body, in that it is composed of natural instruments. For instance, he provides the example of the “body” of a living plant – “the leaf, for instance, is a shelter for the shell, and the shell for the fruit, and similarly the roots correspond to a mouth, since both draw in food” (412b). The natural instruments (organs) of the plant serve their individual purposes with the collaborative “goal” being maintenance of the plant’s survival. The organic natural body of the non-human animal or human being also contains instrument-like organs and parts, which serve individual functions while working to uphold homeostasis, or general wellbeing, of the entire being. This leads us to another specified definition – “Soul is the first actuality of a natural organic body” (412b).
Furthermore, in book three, Aristotle compares the unity of the soul and body to a seal imprint and the wax it is impressed upon (412b). He also draws an analogy of an axe to the natural living body, with “being an axe” as the axe’s substance (and soul). In this case, the axe would no longer truly be an axe just in case this substance were taken away from it. Similarly, if an eye were a living animal and sight (being the soul of the eye) were taken away, it would no longer truly be an eye. Aristotle specifies that only homonymously, both the eye and the axe would remain the eye and the axe after taking away their “souls,” in that they would maintain their names in both respects (with and without the soul). However, their definition of being, corresponding to the names, would be different. Moreover, a body that has lost its soul can no longer be a body that is potentially alive. The only bodies that are potentially alive are the matter of the living, compound body, and the “seed” or “fruit” that can become the compound body. It seems, until this point, that Aristotle believes there is some sort of unity between the soul and the body. However, he later suggests – “it is still unclear whether the soul is the actuality of the body in the way a sailor is of a ship” (413a). The sailor of the ship is able to leave the ship, and the ship remains a ship despite the sailors’ absence. If this were the case for the body and soul, the body would be able to maintain its identity as a body without the presence of the soul. While previously this would have been distinctly homonymous, it now seems that Aristotle is leaving room for the possibility of some sort of separability. Specifically, some parts of the soul may not necessarily be actualities of a body, if the soul is divisible into parts.
Aristotle defines living as “what distinguishes things with souls from things without souls.” In order to understand the soul, it is necessary to understand the forms of life which Aristotle specifies, for whatever has even one of these forms is considered living. However, plants and humans beings, for instance, are not the same in that they have different kinds of souls with different capacities. Aristotle contradicts Empedocles’ belief that in earth growing downward and fire naturally moving upwards, this is how plants grow (by putting roots down on the earth and by extending upwards). Rather, the unqualified cause of this growth and nourishment, according to Aristotle, is the soul. The part of the soul that belongs to the plant is called nutritive, which is what allows it to grow and be nourished, and also to reproduce. The ability to generate or reproduce is critical, and according to Aristotle, it is “the end they [living things] all strive for” (415b). These nutritive capacities are maintained as the foundation of all things.
While some things, such as plants, have only one potentiality (or capacity) of the soul, other things have more than one, and other things have all of the potentialities. There is a sort of hierarchy of the souls, in that whichever has the “higher” capacities will also maintain the “lower” capacities, and plants contain only the lower capacities of nourishment. Animals contain these same nutritive capacities as plants, and additionally have the perceptive part of the soul, in that they are able to actively touch and feel. Moreover, the ability to perceive (pleasure and pain) implies that they will also have the capacity to desire, as well as appetite for things that are pleasant which they will, in turn, desire. Touch is necessary as a foundation for the other senses, but touch can also occur alone within an animal. According to Aristotle, “touch is the primary type of perception belonging to all animals” (413b), and even without motion or locomotion (change of place), whatever has perception is said to be an animal. Furthermore, the human being is at the highest end of this hierarchy of souls, in that they contain all of the previous capacities, as well as the thinking part and intellect (by which the soul thinks and supposes). The intellectual part of the soul and the perceiving part of the soul are unmixed and separate, moreover, they are unaffected in different ways. Similar to Anaxagoras’ idea of the intellect “mastering” surrounding things and other parts of the soul, Aristotle confirms that it is necessary for the intellect to be both unaffected and “unmixed” in order to function properly. As Aristotle describes – “For after a sense perceives something very perceptible, it cannot perceive; after hearing very loud sounds, for instance, it cannot hear sound, and after seeing vivid colors or smelling strong odors, it cannot see or smell” (429b). The perceiving part requires a body, and this is why it is heavily affected by these things, while the intellect is apparently separable and, therefore, un-hindered. Aristotle states, “the straight is similar to the snub, since it requires something continuous. But if being straight is different from the straight, then so is the essence of straight different from the straight, and therefore to discriminate we use something different, or something in a different state” (429b). Essentially, intellect is an object of intellect, and in the same way that an object is separable from matter, intellect is separable from the body. The intellect is unaffected, but still receptive of the forms. In this way, it [productive intellect] is “precisely what it is, all by itself” (430a). According to Aristotle, without this intellect, nothing is capable of understanding.
The soul is divided into parts which correspond to different potentialities. These parts are different in account, and characterize the being which they belong to. The soul of a living thing involves its capacity to engage in certain activities which are characteristic of living things of its sort, and as such, a body will be specific in kind to the capacities of a given soul. For instance, a living plant will always contain a nutritive soul, which is different from the soul of a living animal, which contains nutritive capacities as well as perception, and sometimes locomotion. In book one, Aristotle mentions the example of the sailor – “it is still unclear whether the soul is the actuality of the body in the way a sailor is of a ship” (423a). Later, it is clarified that this analogy does not align with Aristotle’s final definition of the soul. The sailor has capacities that can be exercised independently of the ship, while the soul requires the body in order to exercise its capacities. It is less clear in De Anima whether this rule excludes the intellect, moreover, the capacities of the soul which definitively require the body are at least all of those below the intellect and understanding. The final, comprehensive definition of the soul, which includes all of the specificities of the three books in De Anima, is not compatible with the existence of the soul separate from the body. The soul is not a body – rather, it belongs to a body. In this relationship, there is a co-dependency of sort in upholding certain capacities which are necessary to the living being, whether that being is a plant, non-human animal, or human. Aristotle conveys that the soul is the form, or actuality, of the body. For the sake of analogy, wood for a cabin (as matter) would be potentially that cabin, and the cabin will come to be with the combination of the wood and the form together. The form, then, is the actuality of the cabin, without which the cabin could not have come to be or continue to be. It is like this that the soul and the body are unified, and as such, Aristotle’s concept of the soul-body relationship is not compatible with the existence of soul separate from body.