Descartes, René (1596–1650)

DOI: 10.4324/9780415249126-DA026-1
Version: v1,  Published online: 1998
Retrieved April 21, 2021, from

8. Mind and body

One of Descartes’ most celebrated positions is the distinction between the mind and the body. Descartes did not invent the position. It can be found in various forms in a number of earlier thinkers. It is a standard feature of Platonism and, in a different form, is common to most earlier Christian philosophers, who generally held that some feature of the human being – its mind or its soul – survives the death of the body (see Plato §13). But the particular features of Descartes’ way of drawing the distinction and the arguments that he used were very influential on later thinkers.

There are suggestions, particularly in the Discourse (Part IV) and in the Principles (Part I §§7–8) that the distinction between mind and body follows directly from the Cogito Argument, as discussed above. However, in the Meditations Descartes is quite clear that the distinction is to be established on other grounds. In Meditation VI he argues as follows: I have a clear and distinct idea of myself as a thinking non-extended thing, and a clear and distinct idea of body as an extended and non-thinking thing. Whatever I can conceive clearly and distinctly, God can so create. So, Descartes argues, the mind, a thinking thing, can exist apart from its extended body. And therefore, the mind is a substance distinct from the body, a substance whose essence is thought.

Implicit in this argument is a certain conception of what it means to be a substance, a view made explicit in the Principles (Part I §51) which defines a substance as ‘nothing other than a thing which exists in such a way as to depend on no other thing for its existence’, no other thing but God, of course. In so far as the mind can exist independently of the body, it is a substance on this definition. (God is the third kind of substance, along with mind and body, though because of his absolute independence, he is a substance in a somewhat different sense.) On Descartes’ metaphysics, each substance has a principal attribute, an attribute that characterizes its nature. For mind it is thought, and for body it is extension. In addition, substances have modes, literally ways of instantiating the attributes. So, for Descartes, particular ideas, particular volitions, particular passions are modes of mind, and particular shapes, sizes and motions are modes of body.

Descartes’ conception of mind and body represents significant departures from the conceptions of both notions in the late scholastic thought in which he was educated. For the late scholastics, working in the Aristotelian tradition, body is composed of matter and form. Matter is that which remains constant in change, while form is that which gives bodies the characteristic properties that they have. For Descartes, however, all body is of the same kind, a substance that contains only geometric properties, the objects of geometry made concrete. The characteristic properties of particular forms of body are explained in terms of the size, shape and motion of its insensible parts (see §11 below). For the late scholastics, the mind is connected with the account of life. On the Aristotelian view, the soul is the principle of life, that which distinguishes a living thing from a dead thing; it is also taken to be the form that pertains to the living body. The mind is the rational part of the soul, that which characterizes humans, and not usually considered a genuine substance, though by most accounts, with divine aid, it can survive the death of the body (see Nous; Psychē). For Descartes, the majority of the vital functions are explained in terms of the physical organization of the organic body. The mind, thus, is not a principle of life but a principle of thought. It involves reason, as does the rational soul of the Aristotelians, but it also involves other varieties of thought, which pertain to other parts of the Aristotelian soul (see Aristotle §17). Furthermore, it is a genuine substance, and survives the death of the body naturally and not through special divine intervention.

Mind and body are distinct because they can exist apart from one another. However, in this life, they do not. In Meditation VI Descartes observed: ‘Nature also teaches me, by these sensations of pain, hunger, thirst and so on that I am not merely present in my body as a sailor is present in a ship, but that I am very closely and, as it were, intermingled with it, so that I and the body form a unit’. He sometimes went so far as to say that the human mind is the form of the human body, the only kind of form that he recognizes in nature, and that the human being – the union of a mind and a body – constitutes a genuine substance, though the context of these statements suggests that they may be made more for orthodoxy’s sake than an expression of his own views (see, for example, the letter to Regius, January 1642 (Descartes 1984–91 vol 3: 208), where he is advising Regius on the best way to answer the attacks made by the more orthodox Aristotelian Gisbertus Voëtius in connection with the controversy at Utrecht.) But be that as it may, he was clearly committed to holding that the mind and the body are united. Some of his contemporaries found it difficult to understand how two such different substances could interact and be joined. Sometimes Descartes dismissed this objection by saying that it is no more difficult than understanding how form and matter unite for the Aristotelians, something that everyone learns at school (letter to Arnauld, 29 July 1648; Descartes 1984–91 vol 3: 358). But elsewhere, particularly in an important exchange of letters with the Princess Elisabeth of Bohemia, Descartes offered a different explanation, remarking that it is simply an empirical fact that they do unite and interact, something that we learn from everyday experience, and suggesting that just as we have innate notions that allow us to understand the notions of thinking and extended substance, we also have an innate notion that allows us to comprehend how mind and body interact, and how together they can constitute a unity (letters to Elisabeth, 21 May 1643 and 28 June 1643; Descartes 1984–91 vol 3: 217–20, 226–9).

According to Descartes, the mind is joined to the body in one specific place: the pineal gland, a single gland in the centre of the brain, between the two lobes. This is the spot in which interaction takes place. The mind has the ability to move the pineal gland, and by doing so, to change the state of the brain in such a way as to produce voluntary motions. Similarly, the sensory organs all transmit their information to the pineal gland and, as a result of that, sensation is transmitted to the attached mind. However, because of the interconnection of the parts that make up the organic body, by virtue of being connected to the pineal gland, the mind can properly be said to be connected with the body as a whole (Passions: §§30–2) (see Persons).

Citing this article:
Garber, Daniel. Mind and body. Descartes, René (1596–1650), 1998, doi:10.4324/9780415249126-DA026-1. Routledge Encyclopedia of Philosophy, Taylor and Francis,
Copyright © 1998-2021 Routledge.

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