Read, Stephen - Thinking About Logic: An Introduction to the Philosophy of Logic

This book is an introduction to the philosophy of logic. We often see an area of philosophy marked out as the philosophy of logic and language; and there are indeed close connections between logical themes and themes in the analysis of language. But they are also quite distinct. In the philosophy of language the focus is on meaning and reference, on what are known as the semantic connections between language and the world.

In contrast, the central topic of the philosophy of logic is inference, that is, logical consequence, or what follows correctly from what.