Theories of Mind (Part 1): Cartesian Dualism

Can you make consciousness out of sand? You can squeeze it, punch it, toss it in the air, or do all sorts of things to it. But is any of that sufficient for conscious experience?

This post marks the first installment of my series on philosophical theories concerning the nature of the mind. Is mere sand (or other configurations of particles) sufficient for conscious experience? What is the relation between particles and people?

It is to these questions that we turn in this series. So sit back, relax, and put your thinking cap on!

Before proceeding, it is useful to clarify precisely what we mean when we speak of the mind. By the “mind” and “mental phenomena,” I shall understand aspects of the human person such as:

• Intentionality: the directedness or aboutness of thought toward some object
• Qualia: the raw, qualitative, phenomenal “feel” associated with experiences and other conscious mental states
• Privacy: first-person, privileged, subjective access to one’s own conscious states
• Rationality: the ability (i) to intellectually grasp abstract and universal concepts and propositions, and (ii) to apply formal rules of inference

Without further ado, let’s proceed to section one of this series.

1. Introduction

My aim in this series, as noted above, is to critically appraise four theories about the nature of the mind — Descartes’ substance dualism, Armstrong’s identity theory, Ryle’s behaviorism, and Churchland’s eliminative materialism.

The structure of the series is as follows. The sections will be spread out through a number of posts. In section 2, I will evaluate Descartes’ substance dualism. In section 3, I will evaluate Armstrong’s identity theory. In section 4, I will evaluate Ryle’s logical behaviorism. In section 5, I will evaluate Churchland’s eliminativism. Finally, in section 6, I will give a final determination, based on the previous sections, of which accounts are the most and least plausible, respectively.

2. Descartes’ Substance Dualism

Descartes conceived of the mind (soul, intellect, understanding, res cogitans) and material things as separate, distinct substances. The former is an essentially thinking, conceiving, reasoning, spatially unextended, and experiencing thing. The latter, by contrast, is essentially unthinking, unfeeling, spatially extended, and subject to mechanistic laws.

In section 2.1, I will expound upon Descartes’ central arguments for dualism (presented primarily in Meditation II), whereas in section 2.2 I will critically evaluate them. Finally, in section 2.3, I will evaluate the predominant objections to substance dualism.

2.1 Descartes’ Central Arguments

Descartes provides three central arguments for the non-identity of the mind and the material body. In this section, I outline and motivate these three arguments from (i) conceivability, (ii) dubitability, and (iii) divisibility. The interested reader can consult Descartes’ Meditation II for further explication.

2.1.1 From Conceivability

Descartes’ argument from conceivability (189R) runs as follows:

P1: It is conceivable that my mind exists in the absence of anything material.

P2: Whatever is conceivable is possible.

C1 (P1, P2): Hence, it is possible that my mind exists in the absence of anything material.

P3: The possibility that my mind exists in the absence of anything material entails that my mind is not identical to anything material.

C2 (C1, P3): Hence, my mind is not identical to anything material.

P4: If my mind is not identical to anything material, then my mind is an immaterial substance and substance dualism is true.

C3 (C2, P4): My mind is an immaterial substance and substance dualism is true.

2.1.2 From Dubitability

Descartes’ argument from dubitability runs as follows:

P1: My mind does not have the property of being dubitable by me, whereas any material thing has the property of being dubitable by me.

P2: If my mind does not have the property of being dubitable by me, whereas any material thing has the property of being dubitable by me, then my mind and any material thing do not share all of their properties in common.

P3: Necessarily, if x and y are identical, x and y share all of their properties in common.

C1 (P1, P2, P3): Hence, my mind is not identical to any material thing.

P4: If my mind is not identical to any material thing, then my mind is an immaterial substance and substance dualism is true.

C2 (C1, P4): My mind is an immaterial substance and substance dualism is true.

Descartes held that his own existence was certainly and indubitably known. For he could not doubt his own existence, since the very act of doubting presupposes his existence as a doubting, thinking thing. On the other hand, he could doubt the existence of any material thing, since they could all be the products of a vivid dream or the concoctions of a malicious demon. Hence, material things are dubitable by Descartes, whereas Descartes (qua thinking thing) is not dubitable by Descartes. Hence, Descartes and material things do not share all their properties in common. Thus, reasons Descartes, he must not be identical to anything material (i.e. he is an immaterial mind).

2.1.3 From divisibility

In the argument to follow, x is divisible provided that x can be broken down into distinct, self-subsistent, component parts. Descartes argues that mind and material body cannot be identical, as “body is by nature always divisible, and the mind is entirely indivisible. For, as a matter of fact, when I consider the mind, that is to say, myself inasmuch as I am only a thinking thing, I cannot distinguish in myself any parts, but apprehend myself to be clearly one and entire”¹. This argument from divisibility (192L) proceeds as follows:

P1: Anything material is divisible (i.e. can be broken down into distinct, self-subsistent, component material parts).

P2: The mind is not divisible (i.e. the mind is an essentially simple and unified thing, not possibly broken down into self-subsistent parts).

P3: If the mind is not divisible and anything material is divisible, then my mind and any material thing do not share all of their properties in common.

C1 (P1, P2, P3): Hence, my mind and any material thing do not share all of their properties in common.

P4: Necessarily, if x and y are identical, x and y share all of their properties in common.

C2 (C1, P4): Hence, my mind is not identical to any material thing.

P5: If my mind is not identical to any material thing, then my mind is an immaterial substance and substance dualism is true.

C3 (C2, P5): My mind is an immaterial substance and substance dualism is true.

We will turn to analysis and evaluation of such arguments next time. Stay tuned!

Author: Joe

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