In this paper I argue for a doctrine I call 'infallibilism', which I stipulate to mean that If S knows that p, then the epistemic probability of p for S is 1. Some fallibilists will claim that this doctrine should be rejected because it leads to scepticism. Though it's not obvious that infallibilism does lead to scepticism, I argue that we should be willing to accept it even if it does. Infallibilism should be preferred because it has greater explanatory power than fallibilism. In particular, I argue that an infallibilist can easily explain why assertions of 'p, but possibly not-p' (where the 'possibly' is read as referring to epistemic possibility) is infelicitous in terms of the knowledge rule of assertion. But a fallibilist cannot. Furthermore, an infallibilist can explain the infelicity of utterances of 'p, but I don't know that p' and 'p might be true, but I'm not willing to say that for all I know, p is true', and why when a speaker thinks p is epistemically possible for her, she will agree (if asked) that for all she knows, p is true. The simplest explanation of these facts entails infallibilism. Fallibilists have tried and failed to explain the infelicity of 'p, but I don't know that p', but have not even attempted to explain the last two facts. I close by considering two facts that seem to pose a problem for infallibilism, and argue that they don't.
- concessive knowledge attributions
- epistemic modals