- (Premise) If presentism is true, reality is present reality.
- (Premise) All contingent facts about present reality have explanations in terms of how the world used to be.
- So, all contingent facts about present reality have explanations. (By (2))
- So, if presentism is true, all contingent facts have explanations. (By (1) and (3))
It is, of course, unclear that the presentist can deliver on (4), since it is not clear that the presentist really can explain things in terms of how the world used to be. That depends on how well the grounding and causality objections can be answered by the presentist.