  We present a sequent calculus system for a modal reformulation of a system of
nonmonotonic logic due to McCain and Turner: we prove cut elimination for our
system. The proof system is in general infinitary: because we can prove cut
elimination, many applications need, in practice, only the application of
finitary rules. Consequently, nonmonotonic logic is, in many cases, much less
scary than it might seem to be a priori. We derive from this a critique of
Fodor's philosophical worries about the nonmonotonicity of human reasoning.
