According to a standard assumption in epistemology, if one only partially believes that p ,
then one cannot thereby have knowledge that p. For example, if one only partially
believes that that it is raining outside, one cannot know that it is raining outside; and if
one only partially believes that it is likely that it will rain outside, one cannot know that it
is likely that it will rain outside. Many epistemologists will agree that epistemic agents
are capable of partial beliefs in addition to full beliefs and that partial beliefs can be
epistemically assessed along some dimensions. However, it has been generally assumed
that such doxastic attitudes cannot possibly amount to knowledge. In Probabilistic Knowledge, Moss challenges this standard assumption and provides a formidable defense of the claim that probabilistic beliefs—a class of doxastic attitudes including credences and degrees of beliefs—can amount to knowledge too. Call this the probabilistic knowledge claim . Throughout the book, Moss goes to great lengths to show that probabilistic knowledge can be fruitfully applied to a variety of debates in epistemology and beyond. My goal in this essay is to explore a further application for probabilistic knowledge. I want to look at the role of probabilistic knowledge within a “knowledge-centered” psychology—a kind of psychology that assigns knowledge a central stage in explanations of intentional behavior. My suggestion is that Moss’s notion of probabilistic knowledge considerably helps further both a knowledge-centered psychology and a broadly intellectualist picture of action and know-how that naturally goes along with it. At the same time, though, it raises some interesting issues about the notion of explanation afforded by the resulting psychology.