Volume 7, Issue 1, Spring-Summer 2004
Colin P. Ruloff
Plantinga’s S5 Modal Argument, Obvious Entailment, and Circularity
Response to Sennett
In the second chapter of his Modality, Probability and Rationality, James Sennett argues that Plantinga’s famed S5 Modal Argument (hereafter “MA”) for the existence of an unsurpassably great being is objectionably circular since it’s impossible for one to understand the premises of Plantinga’s MA without understanding these premises to logically entail its conclusion. That is to say, Sennett’s charge is that Plantinga’s MA is circular since there is no understanding of the premises of Plantinga’s MA that is independent of its conclusion. In this paper I argue that Sennett has shown no such thing and that, contrary to strong prima facie appearances, there is an understanding of the premises of Plantinga’s MA that is independent of its conclusion. Consequently, Plantinga’s MA is not circular in
the way that Sennett alleges.