I used to think the following principle was certainly true, if → indicates subjunctive conditionals:
- If p→q and p is possible, then q is possible.
But there seems to be a counterexample to (1). Suppose God promised to do A, and did A. Moreover, suppose that the circumstances are such that he is obligated to keep this promise (none of the defeaters for the duty of promise-keeping, if there can be any, apply; the promise has not been annulled by promisee's release; etc.). The following appears true;
- Had God not done A (or something better), he would have done something wrong.
The argument against (1) does not apply on views of counterfactuals on which relevant background assumptions automatically get imported into the antecedent. For part of the background here will be that God made the promise, and that the circumstances were such that he was obligated to keep it. But views like the Lewis-Stalnaker view, on which (a) there is no importation of background assumption, but (b) rule (1) holds, will have a problem here.