Routledge History of Philosophy Volume IV

RENAISSANCE AND SEVENTEENTH-CENTURY RATIONALISM 379
fact that our minds are substances. Leibniz seems to have been pleased with this
theory, and it inspires some of his best-known remarks about innate ideas; it
underlies such claims as ‘We are innate to ourselves’ and ‘There is nothing in the
intellect which was not previously in the senses, except the intellect itself’. 105
None the less, for all Leibniz’s evident pride in the doctrine, it does not seem
very satisfactory. For one thing, on this account ideas turn out to be innate only
in the minimal sense that they are not acquired through the senses. Moreover, the
theory faces obvious difficulties in explaining our acquisition of mathematical
concepts, and these are generally numbered among the explananda for any
theory of innate ideas. We may perhaps acquire the idea of substance by
reflecting on the fact that our minds are substances, but we can hardly acquire
the concept of a triangle by reflecting on the fact that our minds are triangular.
So far we have been chiefly concerned with Leibniz’s defence of a theory of
innate ideas against the Lockean objection that it must reduce to triviality. But
what positive arguments does Leibniz offer in favour of the innatist doctrine? In
the New Essays Leibniz is much more forthcoming on this score in connection
with innate propositions than with innate concepts. In part this fact reflects the
emphasis of Locke’s own discussion, but it also testifies to Leibniz’s concern
with a problem which has exercised philosophers at least since Plato: this is the
problem of explaining how we can have a priori knowledge of necessary truths,
as we do in the case of mathematics. Leibniz follows the Platonic tradition by
arguing that it is impossible to explain such knowledge except on the assumption
that it is innate in our minds. 106 Through the senses, for example, we may perhaps
come to believe that the Pythagorean theorem is true of all observed right-angled
triangles, but we would never come to believe that this theorem expresses a
necessary truth about such triangles.
Leibniz’s case for innate knowledge has a distinguished ancestry, but it seems
to be in danger of running together two separate issues. 107 In the first place, there
is a causal question: how do we acquire beliefs to the effect that necessarily p?
Second, there is a question of justification: how do we justify our claim to know
that necessarily p? Leibniz sometimes seems to say that both questions can be
answered in terms of an appeal to innateness, but this claim is distinctly dubious.
The hypothesis of innateness may be a plausible answer to the first question, but
it is more difficult to see how it helps with the second, normative issue; on the
face of it, it seems entirely possible that our innate beliefs should all be false. It
is true that the innatist hypothesis would help to answer the second question on
the further assumption of divine benevolence; a good God can be trusted not to
inscribe a pack of lies on our minds. Unlike Descartes, however, Leibniz is
reluctant to appeal to divine benevolence in order to solve epistemological
questions.
Leibniz’s philosophy, and his metaphysics in particular, is an extraordinarily
ambitious work of synthesis. His system seeks, for example, to combine
Aristotelian and Cartesian insights within a framework of Christian theology.
Sometimes Leibniz’s attempts at synthesis seem overambitious and even