The Unity of Body and Soul in Aristotle

    Through one’s philosophical studies and explorations, one finds that questions of ontology constitute the most fundamental questions of philosophy, and even of life. Big questions, like what is the meaning of life, is there a purpose to reality, or is there a God all represent, in the final analysis, ontological questions. Questions about causation, material composition, and teleology all ultimately relate to questions of ontology; questions about the fundamental nature and being of things. Thus, the question of what constitutes the human person is an ontological question which ought to be answered through an analysis of the being of the human person.

In response to this ontological question about the fundamental nature of the human person, Aristotle provides an analysis of the human person where the matter, soma, and soul, psyche, compose the human being. His theory is unique in the contemporary philosophical landscape as his view does not simply predate Descartes, but, rather, proposes that the material cannot exist without the immaterial and vice versa. Moreover, within Aristotle’s ontology of the human being, which also applies to all other living beings, one finds a place for teleology and purpose built into the very being of all human beings — something which Descartes thoroughly rejected in his substance dualism.

This essay will explore Aristotle’s ontology of living beings, with a special focus on human beings, by elucidating the role of hylomorphism and teleology in his account of living beings. Within each section, Descartes’s position of mind-body substance dualism will function as a foil to Aristotle’s position so that Aristotle’s view can be more fully illuminated. Ultimately, Aristotle thinks that matter, soma, and soul, psyche, composes all living beings are inseparable because they are parts of one substance, rather than two distinct substances which interact in an ad hoc fashion.

In order to begin this analysis, Aristotle provides a succinct definition of his hylomorphic view, as applied beings in general, in De Anima:

We describe one class of existing things as substance; and this we subdivide into three: (1) matter, which in itself is not an individual thing; (2) shape or form, in virtue of which individuality is directly attributed, and (3) the compound of the two. Matter is potentiality, while form is realization or actuality, and the word actuality is used in two senses, illustrated by the possession of knowledge and the exercise of it. (De Anima 412a7-14)

Aristotle thinks that all material substances are composites of matter and form. Aristotle views form as the fundamental principle of actuality in things, while he conceives of matter as the fundamental principle of potentiality in things. In other words, form confers an intelligible structure onto a substance, while matter accounts for how that substance can change while remaining the same. This theory goes beyond simply being a theory of mind or living creatures, but characterizes all substances at all levels of reality for him, from atoms to human beings. However, the theory has a special application to living creatures as Aristotle refers to the forms of living beings as something unique: the soul. In the following section from De Anima, Aristotle briefly discusses the function of the soul: 

The soul may therefore be defined as the first actuality of a natural body potentially possessing life; and such will be any body which possesses organs. (The parts of plants are organs too, though very simple ones: e.g., the leaf protects the pericarp, and the pericarp protects the seed; the roots are analogous to the mouth, for both these absorb food.) If then one is to find a definition which will apply to every soul, it will be “the first actuality of a natural body possessed of organs.” (De Anima 412a29-412b6)

Here, Aristotle applies his hylomorphism to living beings and living beings actually provide a wonderful example of how he thinks matter and form relate to each other. He affirms that the soul, the form of the body, represents the most fundamental principle of actuality in the living thing, which he signifies by calling it “the first actuality of a natural body” (De Anima 412a29). The form then completely and totally structures the matter in its own image, as it were, realizing the conceptual content in itself fully in the matter, thus resulting in an informed material body. Aristotle denotes this reality when he speaks of the organs as exemplifiers of, to use a contemporary term, the form-in-matter, or more properly the soul-in-matter. 

Once again, the passage from Aristotle above communicates his theory of living beings in general, applying to creatures from bacteria to human beings, but, as before, Aristotle views the human soul, also called the rational soul by him, as possessing unique properties and abilities. These special properties and abilities ultimately boil down to the reality of rationality in the human soul, not present in any other known animal according to Aristotle. The human soul contains within itself the vegetative and animal, or appetitive, faculties found in plants and animals, but also has at its highest level rational faculties. These include faculties such as intellect and will, and, indeed, can sometimes operate immaterially, as it were, when performing high level abstraction and operating at the level of pure concepts and ideas. However, the faculty can only exist while the form exists and the form only exists while conjoined to its matter since matter and form constitute one substance. Thus, even though Aristotle thinks that the highest operations of the rational faculty can function immaterially, they still rely on the soul-in-matter to exist and so cannot persist after death.

In stark contrast, Descartes’s conception of the mind-body relation represents the modern and contemporary notion. He viewed the mind and body as separate substances, by which he meant, in contrast to Aristotle, that the mind and body can exist apart from each other. The root of this idea was his challenging of the Aristotelian notion of prime matter, or matter as pure potency or potentiality apart from form. This disputation of Aristotle prime matter began in late Scholasticism with figures like Bl. Duns Scotus and William of Ockham, but Descartes is the first figure to develop a truly modern conception of matter, and form a theory of mind upon that theory of matter. Contemporary discussions in the philosophy of mind assume Descrates’s substance dualism framework, which makes Aristotle's view that the body and soul are inseparable difficult for modern ears to understand.

Furthermore, Aristotle’s affirmation of teleology also makes his hylomorphic view of living beings unique in a contemporary context. Aristotle held to essentialism, which states that all substances have an essence or nature which makes them the things they are. Inherent in essentialism is the notion that since things have an essential nature without which they would not be that thing, they also have a built-in purpose as a result of that essential nature. For Aristotle, this essential nature is conferred on a substance by its form. Thus, the form confers the purpose or telos, end, of the thing onto the whole substance, including both matter and form. Therefore, Aristotle accounts for teleology by positing that substances are matter-form composites, making teleology inextricably linked to hylomorphism, on his view.

Once more, Descartes stands in contrast to Aristotle, viewing teleology as an unprovable and unnecessary postulate. A major reason for this, of course, is his denial of hylomorphism because without it, Descartes has no way to account for how essences or natures are conferred on substances and so has no way to account for the built-in purposefulness of those substances.

In conclusion, Aristotle held to hylomorphism, which maintains that all material beings consist of matter and form. Thus, he thought that matter, soma, and soul, psyche, were inseparable in living beings since they are both equally important components of one substance. The modern philosophical tradition, following Descartes, views the body and soul as separate substances which interact with each other, but possess no essential tie to each other. Moreover, the metaphysics of hylomorphism naturally account for teleology, while the early modern view’s rejection of teleology, at least in part, flows from its denial of hylomorphism. In light of contemporary philosophy of mind’s struggle to explain consciousness and the unity of the human person within the assumed Cartesian framework, Aristotle’s hylomorphic view of mind should be investigated as a possible alternative to the dominant framework which could provide greater explanatory power.

Works Cited

Ainsworth, Thomas. “Form vs. Matter (Stanford Encyclopedia of Philosophy).” Stanford.edu, 2016, plato.stanford.edu/entries/form-matter/.

Aristotle, and Robert Drew Hicks. De Anima. Hicks Press, 2007.

Hatfield, Gary. “René Descartes (Stanford Encyclopedia of Philosophy).” Stanford.edu, Stanford University, 3 Dec. 2008, plato.stanford.edu/entries/descartes/.

Shields, Christopher. “Aristotle.” Stanford Encyclopedia of Philosophy, 25 Sept. 2008, plato.stanford.edu/entries/aristotle/.

Spade, Paul Vincent, and Claude Panaccio. “William of Ockham.” Stanford Encyclopedia of Philosophy, Metaphysics Research Lab, Stanford University, 2019, plato.stanford.edu/entries/ockham/.

Williams, Thomas. “John Duns Scotus.” Stanford Encyclopedia of Philosophy, Metaphysics Research Lab, Stanford University, 2019, plato.stanford.edu/entries/duns-scotus/.