Does Kant Reduce the Cosmological Proof to the Ontological Proof?

DOES KANT REDUCE THE COSMOLOGICAL PROOF TO THE ONTOLOGICAL PROOF? JOHN PETERSON The University of Rhode Island Kingston, Rhode Island KANT ARGUES in the Dialectic that the cosmological proof fails because it feeds on the central proposition of the ontological proof.1 The ontological proof he has in mind is that of Descartes.2 The proposition he refers to, call it H, is that the highest being is a necessary being. In Descartes's proof in the fifth Meditation H is construed as asserting that existence is found in the concept of ens realissimum, the highest being. From the fact that I cannot conceive a triangle whose angles do not equal two right angles it does not follow that a triangle exists. This is because having angles that equal two right angles belongs to the concept of a triangle while existence does not. It follows in the view of Descartes that because I cannot conceive a non-existent ens realissimum existence belongs to the concept of an ens realissimum. Kant denies that the inconceivability of a non-existent ens realissimum implies that consequence. For the inference assumes that existence is a predicate and it is not. Otherwise, says Kant, the concept of a hundred real dollars is different from the concept of a hundred imaginary dollars and it is not. On this point Aquinas agrees with Kant. You can know perfectly well what a phoenix is, says Aquinas, even if you do not know there is a phoenix, showing that existence adds something to the essence or concept of a phoenix.3 Be that as it may, 1 Immanuel Kant, Critique of Pure Reason, translated by Norman Kemp Smith (London, 1958) A 603, B631ff; pp. 507 ff. 2 Ibid., A 602, B 630; pp. 507 ff. 3 St. Thomas Aquinas, On Being and Essence, translated by A. Maurer (Toronto, 1949), p. 46. 463 464 JOHN PETERSON as Kant believes that H falsely assumes that existence is a predicate , he concludes that the cosmological proof fails for the same reason the ontological proof fails. How the cosmological proof requires H Kant spells out by distinguishing two phases in the proof. The first phase gives the appearance that the proof is radically different from the ontological proof since, in the minor premise of this phase (CP1-2 below ), appeal is made to experience. At its onset, therefore, the cosmological proof does differ from the ontological proof which shuns experience altogether and proceeds by concepts alone. But in the view of Kant, this difference masks the ultimate dependence of the proof on the same proposition, H, which governs the ontological proof. And this is made evident in phase 2 of the proof. Phase 1 of the proof goes as follows : CPl 1 If anything exists, an absolutely necessary being must also exist. 2 Now I, at least, exist. 3 Therefore an absolutely necessary being exists. What at best CPl shows is that there is a necessary being and not that the necessary being is the highest being or God. What must be added is what Kant calls the nervus probandi of the cosmological proof, namely, that the necessary being is the highest being. But this final conclusion of the proof is deduced only by invoking H, says Kant. I here summarize Kant's review of phase 2 of the proof : CP2 1 If every necessary being is the highest being then some highest being is a necessary being (by conversion per accidens). 2 What is true of some highest being is true of any highest being. 3 Hence, if every necessary being is the highest being then any highest being is a necessary being (from 1 and 2). 4 But if " a necessary being is the highest being" implies " the highest being is a necessary being," then " the highest being is a necessary being " implies " a necessary being is the highest being " (from 3 and conversion simpliciter). 5 But, H, the highest being is a necessary being (by definition). 6 Therefore, a necessary being is the highest being (from 4 and 5). KANT ON THE COSMOLOGICAL PROOF 465 CPl-3 and CP2-6 are then joined to yield the final conclusion that God...