 The two-valued truth table interpretation of classical propositional logic \(\mathbf{CPC}\) gives rise to a simple proof that every admissible rule of \(\mathbf{CPC}\) is derivable: otherwise, some assignment to \(A,\) \(B,\) etc. would make the hypothesis true and the conclusion false, and by substituting e.g. \(P \rightarrow P\) for the letters assigned “true” and \(P \oldand \neg P\) for those assigned “false” one would have a provable hypothesis and unprovable conclusion. The fact that the intuitionistic situation is more interesting leads to many natural questions, some of which have recently been answered.