A promising response to the threat of external world skepticism involves arguing that our commonsense view of the world best explains the sensory experiences that we have. Since our commonsense view of the world best explains our evidence, we are justified in accepting this commonsense view of the world. Despite the plausibility of this Explanationist Response, it has recently come under attack. James Beebe has argued that only a version of the Explanationist Response that provides an a priori justification of inference to the best explanation can hope to respond to two serious objections. Additionally, he has argued that providing such an a priori justification requires an acceptable account of a priori probability and that it is unclear whether such an account can be developed. In this paper I argue that Beebe fails to provide adequate support for either of these claims.