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,