Routledge History of Philosophy Volume IV

208 RENAISSANCE AND SEVENTEENTH-CENTURY RATIONALISM
Descartes’s way round this impasse is to invoke an innate, divinely ordained,
power of the human mind. In creating the human soul, God structured it in such a
way that various sensory experiences will ‘arise’ in it whenever the body to
which it is united is stimulated in a certain way. Thus, the mind has the innate
capacity of ‘representing colours to itself on the occasion of certain corporeal
motions [in the brain]’. There is, in effect, no genuine causal transmission
between mind and body; ‘nothing reaches the mind from external objects except
corporeal motions’; we make judgements about external things ‘not because
these things transmit ideas to our mind through the sense organs, but because
they transmit something which, at exactly the right moment, gives the mind the
occasion to form these ideas by means of the faculty innate to it.’ 104 What we
have here is something powerfully reminiscent of developments later in the
seventeenth century—the occasionalism of Malebranche, and the Leibnizian
theory of ‘pre-established harmony’. And the lesson to be learned from this is
that the ideas of Malebranche and Leibniz were not, as is sometimes suggested,
bizarre attempts to cobble together an ad hoc solution to the problem of mindbody
interaction which Descartes had bequeathed to Western philosophy; rather,
they take their cue from Descartes’s own terminology, and his insistence that the
relationship between physical events and mental phenomena must be explained
on the model of divinely decreed correlations rather than transparent causal
transactions. The heterogeneous worlds of mind and matter cannot, properly
speaking, interact; only the decrees of God can ensure that they work
harmoniously together.
To conclude from this that Descartes’s theory of the mind is a failure would be
easy enough; but any sense of superiority that the modern commentator may feel
should be tempered by the thought that, even today, the relationship between
brain occurrences and conscious experience is very far from having been
elucidated in a coherent and philosophically satisfying way. What may be a more
fruitful theme for reflection is Descartes’s own implicit recognition of the limits
of human knowledge. The Cartesian project for a unified system of knowledge,
founded on transparently clear first principles, faltered, as we saw in the first half
of this chapter, when the human mind came to confront the incomprehensible
greatness of God. And in a different way, the project faltered when it came to
integrating into science that most basic fact of human awareness—our everyday
experience, through our external and internal senses, of the world around us and
the condition of our bodies. To ‘explain’ that awareness, Descartes was
constrained to admit that only the decrees of God, ultimately opaque to human
reason, will suffice. Causal transparency gives way to mere regular conjunction.
If this, once again, seems to prefigure the thought of Hume, that should perhaps
be no surprise. For however much commentators may wish to present it as a
contest between opposing teams of ‘rationalists’ and ‘empiricists’, the history of
the early modern period is a continuous unfolding tapestry in which the threads
endlessly cross and re-cross. The picture that has come down to us is the work of