Hume / (English Men of Letters Series)

by Thomas Henry Huxley

CHAPTER IX.

THE SOUL: THE DOCTRINE OF IMMORTALITY.

Descartes taught that an absolute difference of kind separates matter, as that which possesses extension, from spirit, as that which thinks. They not only have no character in common, but it is inconceivable that they should have any. On the assumption, that the attributes of the two were wholly different, it appeared to be a necessary consequence that the hypothetical causes of these attributes—their respective substances—must be totally different. Notably, in the matter of divisibility, since that which has no extension cannot be divisible, it seemed that the chose pensante, the soul, must be an indivisible entity.

Later philosophers, accepting this notion of the soul, were naturally much perplexed to understand how, if matter and spirit had nothing in common, they could act and react on one another. All the changes of matter being modes of motion, the difficulty of understanding how a moving extended material body was to affect a thinking thing which had no dimension, was as great as that involved in solving the problem of how to hit a nominative case with a stick. Hence, the successors of Descartes either found themselves obliged, with the Occasionalists, to call in the aid of the Deity, who was supposed to be a sort of go-between betwixt matter and spirit; or they had recourse, with Leibnitz, to the doctrine of pre-established harmony, which denied any influence of the body on the soul, or vice versâ, and compared matter and spirit to two clocks so accurately regulated to keep time with one another, that the one struck when ever the other pointed to the hour; or, with Berkeley, they abolished the "substance" of matter altogether, as a superfluity, though they failed to see that the same arguments equally justified the abolition of soul as another superfluity, and the reduction of the universe to a series of events or phenomena; or, finally, with Spinoza, to whom Berkeley makes a perilously close approach, they asserted the existence of only one substance, with two chief attributes, the one, thought, and the other, extension.

There remained only one possible position, which, had it been taken up earlier, might have saved an immensity of trouble; and that was to affirm that we do not, and cannot, know anything about the "substance" either of the thinking thing, or of the extended thing. And Hume's sound common sense led him to defend this thesis, which Locke had already foreshadowed, with respect to the question of the substance of the soul. Hume enunciates two opinions. The first is that the question itself is unintelligible, and therefore cannot receive any answer; the second is that the popular doctrine respecting the immateriality, simplicity, and indivisibility of a thinking substance is a "true atheism, and will serve to justify all those sentiments for which Spinoza is so universally infamous."

In support of the first opinion, Hume points out that it is impossible to attach any definite meaning to the word "substance" when employed for the hypothetical substratum of soul and matter. For if we define substance as that which may exist by itself, the definition does not distinguish the soul from perceptions. It is perfectly easy to conceive that states of consciousness are self-subsistent. And, if the substance of the soul is defined as that in which perceptions inhere, what is meant by the inherence? Is such inherence conceivable? If conceivable, what evidence is there of it? And what is the use of a substratum to things which, for anything we know to the contrary, are capable of existing by themselves?

Moreover, it may be added, supposing the soul has a substance, how do we know that it is different from the substance, which, on like grounds, must be supposed to underlie the qualities of matter?

Again, if it be said that our personal identity requires the assumption of a substance which remains the same while the accidents of perception shift and change, the question arises what is meant by personal identity?

"For my part," says Hume, "when I enter most intimately into what I call myself, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch myself at any time without a perception, and never can observe anything but the perception. When my perceptions are removed for any time, as by sound sleep, so long am I insensible of myself, and may be truly said not to exist. And were all my perceptions removed by death, and I could neither think, nor feel, nor see, nor love, nor hate, after the dissolution of my body, I should be entirely annihilated, nor do I conceive what is further requisite to make me a perfect nonentity. If any one, upon serious and unprejudiced reflection, thinks he has a different notion of himself, I must confess I can reason no longer with him. All I can allow him is, that he may be in the right as well as I, and that we are essentially different in this particular. He may perhaps perceive something simple and continued which he calls himself, though I am certain there is no such principle in me.

"But setting aside some metaphysicians of this kind, I may venture to affirm of the rest of mankind, that they are nothing but a bundle or collection of different perceptions, which succeed one another with an inconceivable rapidity, and are in a perpetual flux and movement.... The mind is a kind of theatre, where several perceptions successively make their appearance, pass, repass, glide away, and mingle in an infinite variety of postures and situations. There is properly no simplicity in it at one time, nor identity in different, whatever natural propension we may have to imagine that simplicity and identity. The comparison of the theatre must not mislead us. They are the successive perceptions only that constitute the mind; nor have we the most distant notion of the place where these scenes are represented, or of the materials of which it is composed.

"What then gives so great a propension to ascribe an identity to these successive perceptions, and to suppose ourselves possessed of an invariable and uninterrupted existence through the whole course of our lives? In order to answer this question, we must distinguish between personal identity as it regards our thought and imagination, and as it regards our passions, or the concern we take in ourselves. The first is our present subject; and to explain it perfectly we must take the matter pretty deep, and account for that identity which we attribute to plants and animals; there being a great analogy betwixt it and the identity of a self or person."—(I. pp. 321, 322.)

Perfect identity is exhibited by an object which remains unchanged throughout a certain time; perfect diversity is seen in two or more objects which are separated by intervals of space and periods of time. But, in both these cases, there is no sharp line of demarcation between identity and diversity, and it is impossible to say when an object ceases to be one and becomes two.