Abstract
Ernest Sosa has argued that the relevant alternatives theory of knowledge has yet to overcome serious difficulties. The most serious difficulty is that of providing criteria for when a rival alternative to a claim is relevant. Without such criteria, the theory is ad hoc. I argue that most other externalist theories of knowledge, including Sosa's own, fall victim to this criticism. At the end of the paper I make a suggestion as to why Sosa's objection might not be as damaging as it at first seems.