1 For a taxonomy of ontological arguments, see notably Oppy (1995, 1996).
2 Fifth meditation.
3 Cf. Malcolm (1960).
4 Cf. Plantinga (1974).
5 From Anselm's Proslogion (chapters 2 and 3).
6 Aliquid quo nihil maius cogitari possit.
7 In his Critique of Pure Reason.
8 At least partly, since premises (1) and (4) notably result from a priori considerations.
9 Without yielding certainty.
10 I thank Graham Oppy and Christopher Small for very useful comments on an earlier draft.