proof theory & philosophy

This manuscript is a draft of a guided introduction to logic and its applications in philosophy. The focus will be a detailed examination of
the different ways to understand proof. Along the way, we will also
take a few glances around to the other side of inference, the kinds of
counterexamples to be found when an inference fails to be valid.
The book is designed to serve a number of different purposes, and it
can be used in a number of different ways. In writing the book I have
at least these four aims in mind.