Rourke, J. Philos Stud (2013) 162: 637. doi:10.1007/s11098-011-9786-2
Many epistemologists treat knowledge as a binary relation that holds between a subject and a proposition. The contrastive account of knowledge developed by Jonathan Schaffer maintains that knowledge is a ternary, contrastive relation that holds between a subject, a proposition, and a set of contextually salient alternative propositions the subject’s evidence must eliminate. For the contrastivist, it is never simply the case that S knows that p; in every case of knowledge S knows that p rather than q. This paper offers a counterexample to the contrastive account of knowledge. Part 1 summarizes the contrastive theory developed by Schaffer in a series of recent papers. Part 2 presents an example from a class of cases characterized by compatibility between the proposition p and each of the alternative propositions that occupy q. In such cases the alternative propositions that partially constitute the ternary contrastive relation play no role in the acquisition of knowledge. Part 3 considers and rejects potential responses to the counterexample. The paper concludes that the contrastive theory is not a general account of knowledge.