Plantinga’s modal ontological argument relies on the premise that God’s necessarily existent essence is instantiated or made concrete in at least one metaphysically possible world. Such an argument is arguaby most naturally at home in the context of Platonism about possible worlds. Conditional on that assumption, the following argument challenges the possibility of a Plantingian god by considering in general how any abstract essence might be made concrete or possibly instantiated from within the total space of abstract possibilities. In general, if an entity’s abstract nature is ever made concrete, it must occur via some kind of “instantiator.” There are four logical possibilities for how this might happen:
• (a) Instantiation occurs entirely by an abstract mechanism inherent to the essence itself.
• (b) Instantiation is brought about solely by a concrete agent external to the essence.
• (c) Instantiation is accomplished by a purely abstract mechanism that is partly internal to the essence and partly derived from external abstract entities.
• (d) Instantiation involves a hybrid process that is partly internal (abstract) and partly external (concrete).
Here's the rub. When applied to God’s abstract essence, each of these possibilities creates a tension with traditional theism:
1. Self-Instantiation by an Internal Abstract Agent (a):
If God’s essence instantiates itself through a wholly abstract internal mechanism, then abstract entities would have the capacity to bring themselves into concrete existence. This would imply that other abstract entities might also self-instantiate, contradicting the exclusive nature of God’s self-sufficiency as envisioned in traditional theism.
2. Instantiation by an External Concrete Agent (b):
If instantiation requires a completely external, concrete agent, then something outside of God must do the instantiating. However, traditional theism posits that God is the ultimate and sole ground of all existence, leaving no room for an external instantiator.
3. Joint Instantiation with Other Abstract Entities (c):
Should the process involve an abstract agent partly internal to God and partly drawn from other abstract entities, it would suggest that God’s essence is not unique in its capacity to be instantiated. This again implies that other abstract entities could potentially share in such instantiation, which is at odds with traditional theistic claims.
4. Mixed Abstract and Concrete Instantiation (d):
Finally, if the instantiation involves both an internal abstract component and an external concrete component, it inherits the issues from both (a) and (b): it presupposes self-instantiation while also requiring an external instantiator, a combination that contradicts the traditional view of God’s unique, self-sufficient nature.
Summing up: assuming Platonism about possible worlds, if we assume accept the premise that God’s necessarily existent essence is possibly instantiated in any metaphysically possible world—as required by Plantinga’s modal ontological argument—we encounter a quadrilemma. Every potential account for how such instantiation might occur ends up generating problems that are incompatible with the core tenets of traditional theism. In this way, the assumption that God’s essence can be instantiated poses a serious challenge to Plantinga’s argument and similar modal formulations, calling into question the coherence of their possibility premise--and perhaps the very possibility of traditional monotheism.
