ABSTRACT
This chapter aims to set out proofs of a few more of the important theorems of Principia Mathematica (PM). On the whole, these proofs are a little more difficult than most of the ones set out; but beginners should have no trouble in following them if their have already worked through the earlier ones. In fact, once they have worked beginner’s way carefully through this batch, they should be in a very good position to prove for themselves any theorem of PM they may want to. For Imp asserts that if one proposition implies that a second proposition implies a third, then the first and second propositions jointly imply the third. But this consequent amounts to saying that if the first and second propositions are both true, then the third is true.
