Godel's ontological argument: a reply to Oppy

Abstract

Graham Oppy has contributed recently to the discussion of Godel’s ontological argument with an attempted refutation (Oppy 1996). Although seemingly promising, I will show here that this attempt fails to undermine Godel’s argument. Very briefly, Godel’s argument proceeds in the following way.1 One begins with the primitive notion of a positive property. A positive property is a ‘great-making’ property which entails no defect. The property of Godlikeness (G) is defined in this way: One is God-like iff one has as essential properties all and only positive properties. Given a number of axioms concerning positive properties, one can prove that a unique possible individual instantiates God-likeness, i.e. that there is (at least) one possible world inhabited by this unique God-like being. Furthermore, necessary existence is a positive property. Thus, in some possible world this unique God-like being necessarily exists, and so, in S5 modal logic, this being exists in the actual world. Oppy’s strategy is the strategy which the monk Gaunilo used to try to refute Anselm’s ontological argument. This strategy attempts to show that if the theist purports to have proven the existence of God, the same reasoning may be used to prove the existence of many theologically repugnant entities, e.g. demi-gods, perfect islands, etc. Oppy’s particular objection is motivated in the following way: since the theist defines God-likeness, the atheist may define a similar property, call it ‘God*-likeness’ (‘G*’). Let God*-likeness be the property one has iff one has as essential properties only and almost all of the positive properties, including necessary existence (e.g., all positive properties except omniscience, and only positive properties). Since two things are identical only if they share the same essential properties, the definition of God*-likeness ensures that the atheist’s being is distinct from God. Furthermore, a God*-like being must also be necessarily existent, since necessary existence is a property entailed by God*likeness. Oppy cannot draw the conclusion that such a being exists, however. There is a crucial disanalogy between his argument and the theist’s. This disanalogy becomes evident when we look at Oppy’s argument, which he