Routledge History of Philosophy Volume IV

212 RENAISSANCE AND SEVENTEENTH-CENTURY RATIONALISM
46 cf. H.Frankfurt, Demons, Dreamers and Madmen. The Defence of Reason in
Descartes’ Meditations [6.14].
47 AT X 496; CSM II 400. For the work’s date of composition, see CSM II 399.
48 ‘I am, I exist—that is certain. But for how long? For as long as I am thinking…’
(AT VII 27; CSM II 18).
49 All quotations in this paragraph are from the opening of the Third Meditation: AT
VII 35–6; CSM 24–5.
50 Or what Descartes calls (using scholastic terminology) ‘objective reality’ (realitas
objectiva). The more helpful reference to the ‘representational’ aspect of ideas is
supplied in the 1647 French translation of the Meditations (by the Duc de Luynes)
which was issued with Descartes’s approval.
51 Third Meditation: AT VII 40, 45, 51; CSM II 28, 31, 35.
52 Lumine naturali manifestum est tantundem ad minimum esse debere in causa…
quantum in ejusdem causae effectu…Hinc autem sequitur [non] posse…fieri…id
quod magis perfectum est…ab eo quod minus (AT VII 40; CSM II 28).
53 It is interesting to note that Cartesian physics, in so far as it offers explanations
purely in terms of mathematical covering laws, offers the possibility of dispensing
with traditional models of causality; the opportunity, however, was not fully seized
by Descartes (see pp. 222–5). For more on Descartes’s conception of causality, and
its influence on the philosophical history of the seventeenth and eighteenth
centuries, see N.Jolley, The Light of the Soul [6.19], ch. 3.
54 Conversation with Burman, AT V 156; CB 17. For more on the scholastic
background to Descartes’s causal proof for God’s existence, see J.Cottingham, ‘A
New Start? Cartesian Metaphysics and the Emergence of Modern Philosophy’, in
T.Sorell (Ed.) The Rise of Modern Philosophy [6.37].
55 In the Fifth Meditation, Descartes offers a further proof of God’s existence, namely
that since God is defined as the supremely perfect being, all perfections, including
that of existence, must necessarily be part of his essential nature:
it is quite evident that existence can no more be separated from the
essence of God than the fact that its three angles equal two right angles can
be separated from the essence of a triangle, or than the idea of a mountain
can be separated from the idea of a valley. Hence it is no less of a
contradiction to think of God (that is a supremely perfect being) lacking
existence (that is, lacking a perfection) than it is to think of a mountain
without a valley.
(AT VII 66; CSM II 46) A version of this argument (known since Kant as the
‘ontological argument’) had originally been put forward by St Anselm of
Canterbury in the eleventh century, but it had been strongly criticized by Aquinas,
and its revival by Descartes was a source of considerable surprise to his
contemporaries. For some of the objections raised by contemporary critics, see the
First Set of Objections to the Meditations, AT VII 98; CSM II 70. For a discussion
of some of the problematic aspects of the argument, see further J.Cottingham,
Descartes [6.11], 57ff.