According to the explanationist, we can rely on inference to best explanation to justifiably believe familiar skeptical hypotheses are false. On this view, commonsense beliefs about the existence and character of familiar, medium-sized dry goods provides the best explanation of our evidence and so justifies our belief that we're not brains-in-vats. This explanationist approach seems prima facie plausible until we press the explanationist to tell us what the data is that we're trying to explain by appeal to our beliefs about external objects and how we could have access to it.