Proof and Context

This thesis concerns some overlooked aspects of conversational contexts. It seeks to give an account of how assertions find their place against a background network of presuppositions. The core idea of this thesis is that these assertions are both harder and easier to perform than prevailing theories of context and presupposition make it seem. On the one hand, this network of presuppositions is extremely flexible. Some philosophers have posited rules to the effect that contexts will make the changes necessary to accommodate what a speaker says by default. However, little has been done to explain how these changes will be facilitated when an assertion is vague, probabilistic or incompatible with other presuppositions in play. A full explication of these rules of accommodation must also be able to explain what occurs in these not uncommon cases. On the other hand, we should be skeptical of the tendency to treat these rules of accommodation as universal laws. It is simply not the case that speakers must take for granted all claims put forward during a conversation. When you suspect that I am lying, you might reasonably ask for me to dispel your doubts before you take my word for granted. We expect that speakers are in a position to verify – at least to our satisfaction – the things which they say. The resulting picture, developed in this thesis, is that contexts are quite flexible, but not unlimitedly so.