Whatever Happened to Kant’s Ontological Argument? ian logan Blackfriars Hall, University of Oxford Introduction 1 In the New Elucidation of 1755, Kant first put forward an argument for the existence of God from the concept of possibility, seeking to dem- onstrate that it is impossible to think of the non-existence of that which is the ground of the possibility of things. 2 He developed this argument further as the only basis for a rigorously viable proof of God in The One Possible Basis for a Demonstration of the Existence of God (OPB) of 1763. But when he came to write the Critique of Pure Reason (CPR) in 1781, Kant had apparently discarded what he had previously referred to as the one possible proof, and did not include it in the critique of the proofs of God in the ‘Transcendental Dialectic’. The proofs that he did subject to critique in the CPR were those that he had excluded in the OPB from the realm of possible proofs. Kant’s own proof is of partic- ular interest, because it represents an ‘ontological’ or ‘ontotheological’ argument which is distinct from that of Descartes, and which for Kant does not succumb to his critique of the Cartesian argument. As has been well attested, the subject of this proof evolved from the ens realissimum of Kant’s so-called ‘pre-critical’ thought into the transcendental ideal of 1 My particular thanks are due to Dr M.J. Wood for commenting on more than one version of this paper. 2 I. Kant, A new elucidation of the first principles of metaphysical cognition, in D. Wal- ford (Ed.), Immanuel Kant: Theoretical Philosophy 1755-1770, Cambridge 1992, pp. 1-45: ‘‘if you deny the existence of God, you instantly abolish not only the entire existence of things but even their inner possibility itself’’ (p. 16); ‘‘as soon as you deny the existence of God every concept of possibility vanishes’’ (p. 17). Philosophy and Phenomenological Research Vol. LXXIV No. 2, March 2007 Ó 2007 International Phenomenological Society 346 IAN LOGAN