Alan Hausman

Nelson Goodman argues against those who, like Carnap, claim extensional identity is the criterion for correct constructional definition. Goodman argues that internal logical difficulties sink such a criterion, thus he proposes his own criterion of extensional isomorphism. We argue that Goodman's criterion itself falls prey to his own arguments or else extensional identity is not shown faulty

In his Introduction to Logical Theory, Strawson argues that Aristotelian logic can be given a successful interpretation into ordinary English, but not into the symbolism of Principia Mathematica, on the grounds that Aristotelian logic and ordinary English share something absent in PM, namely, the doctrine of presupposition. It is argued that Strawson is mistaken. PM does justice to the logical rules of Aristotelian logic and also has a fully articulated doctrine of presupposition.