René Descartes

Background

René Descartes (1596–1650), the French mathematician-philosopher conventionally counted the father of modern philosophy, spent most of his productive life in the Dutch Republic and died in Stockholm in the service of Queen Christina. In this wiki he figures for one contribution above all: the early-modern revival of the a priori proof of God. In the Fifth Meditation, per the SEP's account, "Descartes claims to provide a proof demonstrating the existence of a supremely perfect being from the idea of a supremely perfect being," arguing "that there is no less contradiction in conceiving a supremely perfect being who lacks existence than there is in conceiving a triangle whose interior angles do not sum to 180 degrees" (SEP 'Ontological Arguments' §Preamble–Descartes).

The Cartesian family differs from Anselm's in resting explicitly on perfection: God has every perfection; existence is a perfection; therefore God exists. That form is what Immanuel Kant's existence-is-not-a-predicate objection hits squarely — whatever it does to Anselm's own proof — and it is the form Gottfried Wilhelm Leibniz judged incomplete "unless one first shows that the idea of a supremely perfect being is coherent" (SEP §Preamble).

Positions held in this wiki

• The Ontological Argument — the Cartesian variant of the Anselmian family, treated in the article as an early-modern descendant. The SEP judges the argument question-begging against informed atheists, who simply deny that a supremely perfect being is possible.

Key works in our corpus

Corpus gap: none of Descartes' primary texts are ingested. His argument is represented solely through the SEP's 'Ontological Arguments' entry (in corpus), and every claim above is routed through that summary. The public-domain Veitch translation (1901) of the Meditations and Discourse is a candidate acquisition already noted in this profile's stub; the Objections and Replies (Caterus, Gassendi, and Descartes' responses) would give the corpus both sides of the seventeenth-century debate, as the Anselm–Gaunilo file already does for the eleventh.

Principal critics

• Immanuel Kant — the canonical objection: existence is not a real predicate, so it cannot be a perfection (Kant, CPR, 'Of the Impossibility of an Ontological Proof').
• David Hume — nothing distinctly conceivable implies a contradiction when denied; no existential claim is demonstrable a priori.
• Gottfried Wilhelm Leibniz — the friendly critic: the proof is incomplete without a demonstration that all perfections are compossible.
• Graham Oppy — the contemporary taxonomy under which Cartesian arguments beg the question.

See also

• Anselm of Canterbury — the medieval original from which the Cartesian variant descends.
• Alvin Plantinga — the twentieth-century modal successor.
• Baruch Spinoza — the other great rationalist metaphysician of God, driving similar a priori machinery to a radically different terminus.