Material things and the real distinction between mind and body

Do material things exist?

I perceive them clearly as the subject matter of pure mathematics. I believe that anything that I perceive in that way could only be created by God.

(The only reason I have ever accepted for thinking that something could not be made by him is that there would be a contradiction in my perceiving it distinctly.)

I use my imagination when I turn my mind to material things. It also suggests that they really exist.

How does imagination differ from pure understanding?

When I imagine a triangle I see its 3 lines with my mind’s eye as if they were present.

But if I think of a chiliagon, which is a shape with 1,000 sides. I do not imagine 1,000 sides because my imagination is incapable of creating a chiliagon. Yet I understand what a chiliagon is.

Being able to understand is more essential than being able to imagine. Even if I had no power of imagination, I would still be the same person that I am.

This implies that my power of imagining depends on something other than myself.

I can easily understand that if there is such a thing as my body – that is, if my mind is joined to a certain body in such a way that it can contemplate that body whenever it wants to – then it might be this very body that enables me to imagine corporeal things.

So it may be that imagining differs from pure understanding purely like this.

When the mind understands, it somehow turns in on itself and inspects one of its own ideas.

But when it imagines, it turns away from itself and looks at something in the body (something that conforms to an idea – either one understood by the mind or one perceived by the senses).

I can easily see that this might be how imagination comes about if the body exists. Since I can think of no other equally good way of explaining what imagination is, I can conjecture that the body exists.

But this is only a probability.

Even after all my careful enquiry I still cannot see how, on the basis of the idea of corporeal nature that I find in my imagination, to prove for sure that some body exists.

As well as the corporeal nature that is the subject-matter of pure mathematics, I am also accustomed to imagining colours, sounds, tastes, pain and so on – though not so distinctly.

I perceive these much better through the senses, which is how (helped by memory) they appear to have reached the imagination.

So to deal with them more fully, I must attend to the senses – that is, to the kind of thinking that I call ‘sensory perception’.

I want to know whether the things that are perceived through the senses provide me with any sure argument for the existence of bodies.

(1) First of all then, I perceived by my senses that I had a head, hands, feet and other limbs making up the body that I regarded as part of myself, or perhaps even as my whole self.

I also perceived by my senses that this body was situated among many other bodies that could harm or help it; and I detected the favourable effects by a sensation of pleasure and the unfavourable ones by pain.

As well as pain and pleasure, I also had sensations of hunger, thirst, and other such appetites, and also of bodily states tending towards cheerfulness, sadness, anger and similar emotions.

Outside myself, besides the extension, shapes and movements of bodies, I also had sensations of their hardness and heat, and of the other qualities that can be known by touch. In addition, I had sensations of light, colours, smells, tastes and sounds, and differences amongst these enabled me to sort out the sky, the earth, the seas and other bodies from one another.

All I was immediately aware of in each case were my ideas, but it was reasonable for me to think that what I was perceiving through the senses were external bodies that caused the ideas.

For I found that these ideas came to me quite without my consent= I couldn’t have that kind of idea of any object, even if I wanted to, if the object was not present to my sense organs; and I couldn’t avoid having the idea when the object was present.

Also, since the ideas that came through the senses were much more lively and vivid and sharp than ones that I formed voluntarily when thinking about things, and than ones that I found impressed on my memory, it seemed impossible that sensory ideas were coming from within me; so I had to conclude that they came from external things. My only way of knowing about these things was through the ideas themselves, so it was bound to occur to me that the things might resemble the ideas.

In addition, I remembered that I had the use of my senses before I ever had the use of reason; and I saw that the ideas that I formed were, for the most part, made up of elements of sensory ideas. This convinced me that I had nothing at all in my intellect that I had not previously had in sensation. As for the body that by some special right I called ‘mine’ I had reason to think that it belonged to me in a way that no other body did.

There were 3 reasons for this. I could never be separated from it, as I could from other bodies; I felt all my appetites and emotions in it and on account of it; and I was aware of pain and pleasurable ticklings in parts of this body but not in any other body. But why should that curious sensation of pain give rise to a particular distress of mind; and why should a certain kind of delight follow on a tickling sensation?

Again, why should that curious tugging in the stomach that I call ‘hunger’ tell me that I should eat, or a dryness of the throat tell me to drink, and so on? I couldn’t explain any of this, except to say that nature taught me so. For there is no connection (or none that I understand) between the tugging sensation and the decision to eat, or between the sensation of something causing pain and the mental distress that arises from it.

It seems that nature taught me to make these judgments about objects of the senses, for I was making them before I had any arguments to support them.

(2) Later on, however, my experiences gradually undermined all my faith in the senses. A tower that had looked round from a distance appeared square from close up; an enormous statue standing on a high column didn’t look large from the ground.

In countless such cases I found that the judgments of the external senses were mistaken, and the same was true of the internal senses.

What can be more internal than pain? Yet I heard that an amputee might occasionally seem to feel pain in the missing limb. So even in my own case, I had to conclude, it was not quite certain that a particular limb was hurting, even if I felt pain in it.

To these reasons for doubting, I recently added two very general ones. The first was that every sensory experience I ever thought I was having while awake I can also think of myself as having while asleep; and since I don’t believe that what I seem to perceive in sleep comes from things outside me, I didn’t see why I should be any more inclined to believe this of what I think I perceive while awake. The second reason for doubt was that for all I knew to the contrary I might be so constituted that I am liable to error even in matters that seem to me most true.

(I couldn’t rule this out, because I did not know – or at least was pretending not to know – who made me.) And it was easy to refute the reasons for my earlier confidence about the truth of what I perceived by the senses. Since I seemed to be naturally drawn towards many things that reason told me to avoid, I reckoned that I should not place much confidence in what I was taught by nature. Also, I decided, the mere fact that the perceptions of the senses didn’t depend on my will was not enough to show that they came from outside me; for they might have been produced by some faculty of mine that I didn’t yet know.

(3) But now, when I am beginning to know myself and my maker better, although I don’t think I should recklessly accept everything I seem to have got from the senses, neither do I think it should all be called into doubt.

First, I know that if I have a clear and distinct thought of something, God could have created it in a way that exactly corresponds to my thought. So the fact that I can clearly and distinctly think of one thing apart from another assures me that the two things are distinct from one another – that is, that they are two – since they can be separated by God. Never mind how they could be separated; that does not affect the judgment that they are distinct. So my mind is a distinct thing from my body.

Furthermore, my mind is me, for the following reason: I know that I exist and that nothing else belongs to my nature or essence except that I am a thinking thing; from this it follows that my essence consists solely in my being a thinking thing, even though there may be a body that is very closely joined to me.

I have a clear and distinct idea of myself as something that thinks and isn’t extended, and one of body as something that is extended and does not think. So it is certain that I am really distinct from my body and can exist without it.

Besides this, I find that I am capable of certain special kinds of thinking, namely imagination and sensory perception.

I can clearly and distinctly understand myself as a whole without these faculties. But I cannot understand them without me, that is, without an intellectual substance for them to belong to.

A faculty or capacity essentially involves acts, so it involves some thing that acts; so I see that I differ from my faculties as a thing differs from its properties.

There are other faculties – such as those of moving around, changing shape, and so on – which also need a substance to belong to.

But it must be a bodily or extended substance and not a thinking one, because those faculties essentially involve extension but not thought.

I have a passive faculty of sensory perception, that is, an ability to receive and recognize ideas of perceptible objects; but I would have no use for this unless something – myself or something else – had an active faculty for producing those ideas in the first place.

But this faculty cannot be in me, since clearly it does not presuppose any thought on my part, and sensory ideas are produced without my cooperation and often even against my will.