ABSTRACT
In this book, I give you many of the basic tools for sound reasoning. Most introductions to logic cover the same things to some extent, but move more quickly through the early stages: they start with a short discussion of validity, say something about Venns, and use truth-tables (and/or other diagrams like the semantic tableau) to introduce truth-functions. As I do, they include proofs in statement logic. Typically they call this logic 'sentential' or 'propositional'; for why I call it 'statement logic' instead, see Chapter 6. They usually then go on at least as far as quantified logic, which I do not. They also use symbols for the truth-functional constants, where I use words: 'Q v (P → R)' for example instead of 'Q or (if P then R)'. Symbols are necessary at the later stages; but in this very introductory book I avoid them for two reasons.
