The systems of Descartes, Spinoza and Leibniz have one very important characteristic in common, namely, that they all depend upon the category of “substance”. This is a concept which has developed out of the common-sense notion of “thing”. A “substance” is that which has qualities, and is in general supposed to be indestructible, though it is difficult to see why. It acquired its hold over metaphysicians partly because both matter and the soul were held to be immortal, and partly through a hasty transference to reality of ideas derived from grammar. We say “Peter is running”, “Peter is talking”, “Peter is eating”, and so on. We think that there is one entity, Peter, who does all these things, and that none of them could be done unless there were someone to do them, but that Peter might quite well do none of them. Similarly we assign qualities to Peter: we say he is wise and tall and blond and so on. All these qualities, we feel, cannot subsist by themselves in the void, but only when there is a subject to which they belong; but Peter would remain Peter even if he became foolish and short and dyed his hair. Thus Peter, who is regarded as a “substance”, is self-subsistent as compared with his qualities and states, and he preserves his substantial identity throughout all sorts of changes. Similarly in the material world an atom is supposed (or rather was supposed until recently) to preserve its identity throughout all time, however it might move and whatever combinations it might form with other atoms. The concept of “motion”, upon which all physics seemed to depend, was only strictly applicable to a substance which preserves its identity while changing its spatial relations to other substances; thus “substance” acquired an even firmer hold upon physics than upon metaphysics.
Nevertheless, the notion of “substance”, at any rate in any sense involving permanence, must be shut out from our thoughts if we are to achieve a philosophy in any way adequate either to modern physics or to modern psychology. Modern physics, both in the theory of relativity and in the Heisenberg-Schrödinger theories of atomic structure, has reduced “matter” to a system of events, each of which lasts only for a very short time. To treat an electron or a proton as a single entity has become as wrong-headed as it would be to treat the population of London or New York as a single entity. And in psychology, equally, the “ego” has disappeared as an ultimate conception, and the unity of a personality has become a peculiar causal nexus among a series of events. In this respect, grammar and ordinary language have been shown to be bad guides to metaphysics. A great book might be written showing the influence of syntax on philosophy; in such a book, the author could trace in detail the influence of the subject-predicate structure of sentences upon European thought, more particularly in this matter of “substance”. And it must be understood that the same reasons which lead to the rejection of substance lead also to the rejection of “things” and “persons” as ultimately valid concepts. I say “I sit at my table”, but I ought to say: “One of a certain string of events causally connected in the sort of way that makes the whole series that is called a ‘person’ has a certain spatial relation to one of another string of events causally connected with each other in a different way and having a spatial configuration of the sort denoted by the word ‘table’”. I do not say so, because life is too short; but that is what I should say if I were a true philosopher. Apart from any other grounds, the inadequacy of the notion of “substance” would lead us to regard the philosophy of Descartes, Spinoza, and Leibniz as incompatible with modern science. There is of course in all three, a great deal that does not depend upon “substance”, and that still has value; but “substance” supplied the framework and a good deal of the argumentation, and therefore introduces a fatal defect into these three great systems.
I come now to the triad of British philosophers, Locke, Berkeley, and Hume—English, Irish, and Scotch respectively. Perhaps from patriotic bias or from community of national temperament, I find more that I can accept, and regard as still important, in the writings of these three than in the philosophy of their continental predecessors. Their constructions are less ambitious, their arguments more detailed, and their methods more empirical; in all these respects they show more kinship with the modern scientific outlook. On the other hand, Locke and Hume, if not Berkeley, approach philosophy too exclusively from the side of psychology, and are concerned to study Man rather than the universe.
Locke was a contemporary and friend of Newton; his great book, An Essay concerning Human Understanding, was published at almost the same moment as Newton’s Principia. His influence has been enormous, greater, in fact, than his abilities would seem to warrant; and this influence was not only philosophical, but quite as much political and social. He was one of the creators of eighteenth century liberalism: democracy, religious toleration, freedom of economic enterprise, educational progress, all owe much to him. The English Revolution of 1688 embodied his ideas; the American Revolution of 1776 and the French Revolution of 1789 expressed what had grown, in a century, out of his teaching. And in all these movements, philosophy and politics went hand in hand. Thus the practical success of Locke’s ideas has been extraordinary.
When, knowing all this, one comes to read Locke himself, it is difficult to resist a feeling of disappointment. He is sensible, enlightened, minute, but uninspired and (to moderns) uninspiring. One has to remember that his contemporaries found common sense exhilarating after a century of wars of religion and a long struggle with obscurantism. Locke combatted the doctrine of “innate ideas”, according to which we learned only certain things by experience, but possessed our abstract knowledge in virtue of our congenital constitution. He regarded the mind at birth as a wax tablet, upon which experience proceeded to write. Undoubtedly he was, in this matter, more in the right than his opponents, although the terms in which the controversy was waged are not such as a modern could employ. We should say that the innate apparatus of man consists of “reflexes” rather than “ideas”; also that our sense-organs, our glands, and our muscles lead to responses of certain kinds, in which our own organisation plays a part of the same importance as that played by the external stimulus. The element in our knowledge-responses that corresponds to our own bodily organisation might, perhaps, be regarded as representing what Locke’s opponents meant by “innate”. But it does not represent this at all accurately so far as our feelings towards it are concerned. The “innate” ideas were the ideas to be proud of; they embraced pure mathematics, natural theology, and ethics. But nobody is proud of sneezing or coughing. And when Locke tried to show, in detail, how our knowledge is generated by experience, he was liberating philosophy from a great deal of useless lumber, even if his own doctrines were not altogether such as we can now accept.
Locke used his own principles only in ways consistent with common sense; Berkeley and Hume both pushed them to paradoxical conclusions. The philosophy of Berkeley, to my mind, has not received quite the attention and respect that it deserves—not that I agree with it, but that I think it ingenious and harder to refute than is often supposed. Berkeley, as everyone knows, denied the reality of matter, and maintained that everything is mental. In the former respect I agree with him, though not for his reasons; in the latter respect, I think his argument unsound and his conclusion improbable, though not certainly false. However, I will leave the development of my own views to a later chapter, and confine myself to Berkeley’s argument.
Berkeley contended that when, for example, you “see a tree”, all that you really know to be happening is in you, and is mental. The colour that you see, as Locke had already argued, does not belong to the physical world, but is an effect upon you, produced, according to Locke, by a physical stimulus. Locke held that the purely spatial properties of perceived objects really belong to the objects, whereas such things as colour, softness, sound, etc., are effects in us. Berkeley went further, and argued that the spatial properties of perceived objects are no exception. Thus the object perceived is composed entirely of “mental” constituents, and there is no reason to believe in the existence of anything not mental. He did not wish to admit that a tree ceases to exist when we do not look at it, so he maintained that it acquires permanence through being an idea in the mind of God. It is still only an “idea”, but not one whose existence depends upon the accidents of our perceptions.
The real objection to Berkeley’s view is rather physical than metaphysical. Light and sound take time to travel from their sources to the percipient, and one must suppose that something is happening along the route by which they travel. What is happening along the route is presumably not “mental”, for, as we have seen, “mental” events are those that have peculiar mnemic effects which are connected with living tissue. Therefore, although Berkeley is right in saying that the events we know immediately are mental, it is highly probable that he is wrong as to the events which we infer in places where there are no living bodies. In saying this, however, we are anticipating the results of a fuller discussion in a later chapter.
Hume, proceeding from a starting-point essentially similar to that of Locke and Berkeley, arrived at conclusions so sceptical that all subsequent philosophers have shied away from them. He denied the existence of the Self, questioned the validity of induction, and doubted whether causal laws could be applied to anything except our own mental processes. He is one of the very few philosophers not concerned to establish any positive conclusions. To a great extent, I think, we must admit the validity of his reasons for refusing to feel the usual certainties. As regards the Self, he was almost certainly right. As we have already argued, a person is not a single entity, but a series of events linked together by peculiar causal laws. As regards induction, the question is very difficult, and I shall devote a subsequent chapter to it. As regards causal laws, the question, as we shall find later, is the same as the question of induction. On both points Hume’s doubts are not to be lightly dismissed.
The usual modern criticism of Locke, Berkeley, and Hume is that they were unduly “atomistic”. They thought of the mind as a collection of “ideas”, each as hard and separate as a billiard-ball. They had not the conception of continuous change or of integral processes; their causal units were too small. As we have already seen in connection with Gestaltpsychologie and with sentences, the causal unit is often a configuration which cannot be broken up without losing its distinctive causal properties. In this sense, it is true that the traditional British philosophy was too atomistic. But in another sense I do not think it is true, and I think much modern philosophy is confused on this point. Although a configuration may lose its causal properties when broken up into its elements, it nevertheless does consist of these elements related in certain ways; analysis into “atoms” is perfectly valid, so long as it is not assumed that the causal efficacy of the whole is compounded out of the separate effects of the separate atoms. It is because I hold this view that I call the philosophy which I advocate “logical atomism”. And to this extent I regard Locke, Berkeley, and Hume as in the right as against their modern critics. But this also is a topic which will be resumed in a later chapter.