There is, however, a further point, which is very curious. At most times, Leibniz represents the Creation as a free act of God, requiring the exercise of His will. According to this doctrine, the determination of what actually exists is not effected by observation, but must proceed by way of God’s goodness. Apart from God’s goodness, which
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leads Him to create the best possible world, there is no a priori reason why one thing should exist rather than another.
But sometimes, in papers not shown to any human being, there is a quite different theory as to why some things exist and others, equally possible, do not. According to this view, everything that does not exist struggles to exist, but not all possibles can exist, because they are not all “compossible.” It may be possible that A should exist, and also possible that B should exist, but not possible that both A and B should exist; in that case, A and B are not “compossible.” Two or more things are only “compossible” when it is possible for all of them to exist. Leibniz seems to have imagined a sort of war in the Limbo inhabited by essences all trying to exist; in this war, groups of compossibles combine, and the largest group of compossibles wins, like the largest pressure group in a political contest. Leibniz even uses this conception as a way of defining existence. He says: “The existent may be defined as that which is compatible with more things than is anything incompatible with itself.” That is to say, if A is incompatible with B, while A is compatible with C and D and E, but B is only compatible with F and G, then A, but not B, exists by definition. “The existent,” he says, “is the being which is compatible with the most things.”
In this account, there is no mention of God, and apparently no act of creation. Nor is there need of anything but pure logic for determining what exists. The question whether A and B are compossible is, for Leibniz, a logical question, namely: Does the existence of both A and B involve a contradiction? It follows that, in theory, logic can decide the question what group of compossibles is the largest, and this group consequently will exist.
Perhaps, however, Leibniz did not really mean that the above was a definition of existence. If it was merely a criterion, it can be reconciled with his popular views by means of what he calls “metaphysical perfection.” Metaphysical perfection, as he uses the term, seems to mean quantity of existence. It is, he says, “nothing but the magnitude of positive reality strictly understood.” He always argues that God created as much as possible; this is one of his reasons for rejecting a vacuum. There is a general belief (which I have never understood) that it is better to exist than not to exist; on this ground children are exhorted to be grateful to their parents. Leibniz evidently held this
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view, and thought it part of God’s goodness to create as full a universe as possible. It would follow that the actual world would consist of the largest group of compossibles. It would still be true that logic alone, given a sufficiently able logician, could decide whether a given possible substance would exist or not.
Leibniz, in his private thinking, is the best example of a philosopher who uses logic as a key to metaphysics. This type of philosophy begins with Parmenides, and is carried further in Plato’s use of the theory of ideas to prove various extra-logical propositions. Spinoza belongs to the same type, and so does Hegel. But none of these is so clear cut as Leibniz in drawing inferences from syntax to the real world. This kind of argumentation has fallen into disrepute owing to the growth of empiricism. Whether any valid inferences are possible from language to non-linguistic facts is a question as to which I do not care to dogmatize; but certainly the inferences found in Leibniz and other a priori philosophers are not valid, since all are due to a defective logic. The subject-predicate logic, which all such philosophers in the past assumed, either ignores relations altogether, or produces fallacious arguments to prove that relations are unreal. Leibniz is guilty of a special inconsistency in combining the subject-predicate logic with pluralism, for the proposition “there are many monads” is not of the subject-predicate form. To be consistent, a philosopher who believes all propositions to be of this form should be a monist, like Spinoza. Leibniz rejected monism largely owing to his interest in dynamics, and to his argument that extension involves repetition, and therefore cannot be an attribute of a single substance.
Leibniz is a dull writer, and his effect on German philosophy was to make it pedantic and arid. His disciple Wolf, who dominated the German universities until the publication of Kant Critique of Pure Reason, left out whatever was most interesting in Leibniz, and produced a dry professorial way of thinking. Outside Germany, Leibniz’s philosophy had little influence; his contemporary Locke governed British philosophy, while in France Descartes continued to reign until he was overthrown by Voltaire, who made English empiricism fashionable.
Nevertheless, Leibniz remains a great man, and his greatness is more apparent now than it was at any earlier time. Apart from his eminence as a mathematician and as the inventor of the infinitesimal calculus,
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he was a pioneer in mathematical logic, of which he perceived the importance when no one else did so. And his philosophical hypotheses, though fantastic, are very clear, and capable of precise expression. Even his monads can still be useful as suggesting possible ways of viewing perception, though they cannot be regarded as windowless. What I, for my part, think best in his theory of monads is his two kinds of space, one subjective, in the perceptions of each monad, and one objective, consisting of the assemblage of points of view of the various monads. This, I believe, is still useful in relating perception to physics.
CHAPTER XII Philosophical Liberalism
THE rise of liberalism, in politics and philosophy, provides material for the study of a very general and very important question, namely: What has been the influence of political and social circumstances upon the thoughts of eminent and original thinkers, and, conversely, what has been the influence of these men upon subsequent political and social developments?
Two opposite errors, both common, are to be guarded against. On the one hand, men who are more familiar with books than with affairs are apt to over-estimate the influence of philosophers. When they see some political party proclaiming itself inspired by So-and-So’s teaching, they think its actions are attributable to So-and-So, whereas, not infrequently, the philosopher is only acclaimed because he recommends what the party would have done in any case. Writers of books, until recently, almost all exaggerated the effects of their predecessors in the same trade. But conversely, a new error has arisen by reaction against the old one, and this new error consists in regarding theorists as almost passive products of their circumstances, and as having hardly any influence at all upon the course of events. Ideas, according to this view, are the froth on the surface of deep currents, which are determined by material and technical causes: social changes are no more
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caused by thought than the flow of a river is caused by the bubbles that reveal its direction to an onlooker. For my part, I believe that the truth lies between these two extremes. Between ideas and practical life, as everywhere else, there is reciprocal interaction; to ask which is cause and which effect is as futile as the problem of the hen and the egg. I shall not waste time upon a discussion of this question in the abstract, but shall consider historically one important case of the general question, namely the development of liberalism and its offshoots from the end of the seventeenth century to the present day.
Early liberalism was a product of England and Holland, and had certain well-marked characteristics. It stood for religious toleration; it was Protestant, but of a latitudinarian rather than of a fanatical kind; it regarded the wars of religion as silly. It valued commerce and industry, and favoured the rising middle class rather than the monarchy and the aristocracy; it had immense respect for the rights of property, especially when accumulated by the labours of the individual possessor. The hereditary principle, though not rejected, was restricted in scope more than it had previously been; in particular, the divine right of kings was rejected in favour of the view that every community has a right,
