Descartes' Dualism

Introduction

In this essay, I will answer the question: What is a “real” distinction? How persuasive are Descartes’ arguments in support of the real distinction between the mind and the body?

I will first define what a ‘real’ distinction’ is and what Descartes meant by a ‘real distinction’. Once this is clarified, I will go over several of Descartes’ claims and arguments. These include:

• The distinction between mind and body is not just conceptual, but ontological, physical and metaphysical – in other words this distinction is real

• The ontological cause of mind and body are completely different

• The traits of mind and body are completely different to each other – body is divisible and doubtful, but the mind is indivisible and beyond doubt

One quick note; while most English translations of Descartes use the terms ‘mind’ and ‘body’, Descartes originally used the Latin terms ‘res cogitans’ and ‘res extensa’ respectively. I think a more accurate translation of Descartes’ wording in English would be ‘soul’ and ‘matter.’ Descartes is arguing that these two things are genuinely separate and distinct from one another; using the terms mind and body muddies this distinction massively, since modern neurology and biology show that the mind, brain and body are interlinked in one sophisticated integrated machine. By using the term soul instead of mind, it exemplifies the metaphysically distinct nature of soul compared to the material matter of the body - it also clarifies why Descartes invokes God, metaphysics, ontology and religious epistemology in his works. A soul depends on metaphysics; a mind does not necessarily. For these reasons I will use the terms soul and matter. Another way of putting it is for Descartes, mind and soul are one and the same. (Pandya, 2011; Descartes, 1641.)

Essay

A real distinction is when two things are separate in reality, not just separate in concept. Two things are distinct from each other if they can exist separately (Descartes, 1644.) For example, cats and dogs are not only distinct in concept - they have a real distinction between them. For example, there could conceivably be a world with dogs and no cats, or one with cats and no dogs. If two things conceivably can exist separately, they probably are separate things! The differences between cats and dogs are physically, genetically and manifestly real, not just a made-up distinction. This real type of distinction applies to soul and matter for Descartes. Soul and matter are completely distinct not only conceptually, but there is a real physical, metaphysical and ontological distinction between them.

One argument Descartes makes is there could easily be a world with only res extensia and without res cogitans i.e., a world solely of matter. He also points out the opposite: res cogitans can exist without res extensia i.e., you could exist as a thinking being without inhabiting any body or matter whatsoever (Descartes, 1641.) If two things are not dependent on one another and conceivably exist independently of one another, then it is very likely that there is a real distinction between those two things. It is similar approach to cats and dogs but applied to soul and matter.

Another argument Descartes makes is that it is possible to doubt all material matter because the senses are unreliable and can deceive the soul/mind. For example, a straight straw can look bent in water, even though it is straight in reality. Not only does Descartes doubt his senses, but he also doubts whether his body even exists for certain. (Descartes, 1641.) Could his senses be deceiving him about his body being there? Descartes himself had a dream where he woke up and went about his daily routine (Rene Descartes – “I think, therefore I am”, 2015), so why wasn’t his life all a dream? What if an evil demon was keeping him asleep and just toying with his mind? What if everything he experienced was just a dream at the behest of an evil demon taunting him? Even if he was in such a state, Descartes argues he could not doubt he was thinking in such a dream. By pointing this out, he distinguishes between mind and body in the following way:

P1. I can doubt the existence of my senses, my body and the material world.

P2. I cannot doubt the existence of my own mind’s experience (Descartes, 1637.)

C. Matter and mind cannot be made of the same thing. There is a real distinction between them.

Before looking the objections to Descartes’ argument, it is worth clarifying that Descartes makes a metaphysical distinction between soul and matter. For consciousness to control matter, something transcendent beyond matter has to control the material body in order for us to have free will. For Descartes, soul and by extension consciousness is immaterial, and our bodies are material (Descartes, 1641.) This soul originates from the transcendent i.e., God. Descartes’ metaphysical distinction further distinguishes soul (mind) from matter (body), making the distinction between soul and matter even stronger. This distinction leads to the infamous mind-body problem, another topic entirely. (Westphal, 2016.)

Having laid out Descartes’ first argument, Arnauld (1641) counter-argues that Descartes is making an argument from ignorance; a more accurate phrase might be an argument from incomplete knowledge. Arnauld uses the example of a right-angled triangle and someone who doubts Pythagoras’ theorem when looking at it. If someone looks a right-angled triangle, knowing for certain it is right-angled but doubts Pythagoras’ theorem is true because they do not know that a² + b² = c², then that doubt is from ignorance – that person may not have a full picture of what is true, because they do not yet know Pythagoras’ theorem is true. Their doubt about Pythagoras is misplaced and untrue because they are ignorant of the full truth. For Arnauld, the person who looks at the right-angled triangle and doubts Pythagoras’ theorem is like Descartes: like all of us, Descartes is not entirely sure whether mind and matter are separate. Arnauld points out Descartes’ doubt about the physical body being necessary for the existence of the mind could be wrong: what if our minds depend entirely on our bodies existing? It certainly appears that way – cut off someone’s head and they won’t be thinking a lot anymore.

Descartes retorts that Arnauld is using an inaccurate analogy. The ignorant person looking at the right-angled triangle has a partial concept of triangularity – but triangles are hardly the same as self-analysis. When Descartes’ analyses the concept of mind, it is starkly clear to him that it is not the same as matter. Also, when he analyses the concept of matter, it is even clearer that it is different to mind: the concept of mind is not covertly contained in the concept of material matter. There is no cognition or will that is contained in matter. Put another way, one can analyse the material body and brain (something Descartes actually did) but have no idea what was in that person’s mind or what was controlling it in the first place. This means that soul and matter cannot be one and the same thing to Descartes. With this is mind, Descartes makes another argument from a different perspective. He makes a simple point with this argument: matter is divisible, yet soul is indivisible. (Descartes, 1641.)

He argues that being, mind, the soul are not causally dependent on matter. Matter itself is dependent on the extension and change of other matter. An example Descartes uses is candle wax – at one moment a candle can be firm, opaque and an off-white colour at room temperature, but put it into a fire and its form changes entirely. The change of material properties of the candle wax was caused by the heat of the fire, a material property that is dependent on the oxygen in the room and a spark being caused to begin the fire, which are themselves material properties which depend on other pieces of dependent matter – repeat this chain ad infinitum.

The candle’s consistent properties are not its colours, textures, scents or anything we perceive with our senses. Our sense-based experience is like a cloak that hides the real essence or real nature of physical matter. Our sensory information does not reveal matter’s real nature – not even our imagination can truly understand what the candle is. Matter is not as stable nor definable as we assume it is. For Descartes, it is our intellect that can reveal the candle’s essence and ontological basis. The candles consistent properties throughout its transformation are its malleability, extension, position and flexibility. Descartes’ perspective on physics and metaphysics was unusual for the time, because it was more mathematical, rationalistic and abstract than his predecessors’ perspectives. His perspective transcends some of the limitations of the empirical, Aristotelian model of European science and philosophy that preceded him. He contrasts this world of matter which relies on causation (he dubs it ‘extension’) with the world of the soul which relies on no causation, extension or matter whatsoever. In his own wording:

“From this I knew I was a substance whose sole essence or nature is simply to think, and which does not require any place, or depend on any material thing, in order to exist.” (Descartes, 1637)

The soul, the res cogitans, the Cogito does not rely on malleability, quantity, extension, position or any physical quality to exist – its essence is entirely different ontologically, cosmologically and metaphysically to matter. From this perspective, Descartes powerfully demonstrates how distinct soul and matter are from one another and that this distinction is real. We can divide matter into smaller and smaller parts or change matters’ properties. We cannot do any of this to the soul, which is beyond matter and therefore different to it.

A counterargument to Descartes’ arguments here comes from Mersenne. He argues that Descartes’ should not be so certain of his dualism. Mersenne brings up the possibility that what we call mind, thought, being, cognition, the Cogito might be a product of the body itself. Mind might just be body; soul might be the same as matter. Mersenne himself states:

“You say ‘I am a thinking thing’; but how do you know that you are not corporeal or a body which is in motion?” (attributed to Mersenne, 1641.)

Another counterargument to Descartes’ dualism comes from a historical example: our friends the Ancient Greeks. When they saw Phosphorous (the morning star) and saw Hesperous (the evening star) in the sky, they logically believed they were two different bodies in the sky. The Greeks did not know that Phosphorous and Hesperous were in fact the same body in the sky, the planet Venus. Venus appears at dusk and dawn in different places of the night sky, but the Greeks did not know this. This is a belief from ignorance. Likewise, some accuse Descartes of making an argument from ignorance; that he is inferring soul and matter to be different from one another when they are actually just the same thing, just like with Phosphorous and Hesperous actually being Venus all along.

A retort to this counterargument could be that the morning/evening star analogy is inaccurate and misses the point Descartes is making. Phosphorous and Hesperous are both very similar things when we analyse them; they appear as stars in the sky because they are physical objects. They have very similar physical traits, predictable motion, an identifiable form, consistency etc. Soul and matter do not appear similar to one another in any way at all. They do not share extension, physical traits, motion or similar functions. They are not even composed of the same substances; soul may not even be substance at all (Descartes, 1637.) Celestial bodies are hardly sentient beings, so the analogy is inaccurate and the argument somewhat redundant.

Conclusion

I believe Descartes’ arguments for a real distinction between soul and matter, mind and body, res cogitans and res extensia etc are persuasive arguments. I think his breadth and variety of perspectives on the matter add weight to his arguments. I also think some of the counterarguments to his claims are not as powerful as his original arguments, partly because they misconstrue his claims or miss the points he is trying to make. To me, there is a real distinction between mind and body and Descartes arguments persuade me in believing that. This is especially true after writing this essay and thinking on the matter, because I was initially dismissive of Descartes’ dualism but am now persuaded by him.

Bibliography

Arnauld, A. 1641. Fourth Objections.

Descartes, R., 1637. Discourse on the Method of Rightly Conducting One's Reason and of Seeking Truth in the Sciences.

Descartes, R., 1641. Meditations on First Philosophy, in which the existence of God and the immortality of the soul are demonstrated.

Descartes, R., 1644. Principles of Philosophy.

Mersenne, M., 1641. Second Objections.

Pandya, S., 2011. Understanding brain, mind and soul: Contributions from neurology and neurosurgery.

Westphal, J., 2016. The mind-body problem. MIT Press.