Vohánka concocts a short non-theological story whose claims translate into claims of the same form in relative identity logic, and yet are clearly logically impossible.

Vlastimil Vohánka (2013) argues that van Inwagen has done nothing to show the logical possibility of any Trinity theory. Just because a set of claims can’t be proven inconsistent in van Inwagen’s relative identity logic, it doesn’t follow that such claims don’t imply a contradiction, or that it is metaphysically possible that all the claims are true. At one point van Inwagen tells a short non-theological story whose claims, when translated into his relative identity logic, have the same forms as the Trinity propositions. The story, he argues, is clearly not self-contradictory; thus, he conclud...