On an Insufficient Argument Against Sufficient Reason

In one of its versions, the principle of sufficient reason maintains that every true proposition has a sufficient reason for its truth. Recently, a number of philosophers have argued against the principle on the ground that there are propositions such as the conjunction of all truths that are 'too big' to have a sufficient reason. The task of this article is to show that such maximal propositions pose no threat to the principle. According to what is perhaps the most 'popular' version of the principle to sufficient reason (PSR), every true proposition has a sufficient reason why it is true. Peter van Inwagen formulates the principle as follows: 'for every truth, for everything that is so, there is a sufficient reason for its being true or being so.' Like many contemporary philosophers, however, he rejects the principle. My purpose here is to show that the main philosophical argument against PSR rests on a mistaken assumption. There is also a 'scientific' argument against PSR that turns on considerations of quantum indeterminacy; but that argument lies beyond the scope of this discussion.