Henry Johnstone's philosophical development was guided by a persistent need to reform the concept of validity -either by reinterpreting it or by finding a substitute for it. This project lead Johnstone into interesting confrontations with the concept of rhetoric and especiaUy with the work of Chaim Perelman and Olbrechts-Tyteca. The project culminated in a failed attempt to develop a formal ethics of rhetoric and argumentation, but this attempt was itself not consistent with some of Johnstone's other characterizations ofan ethics of (...) argument ation. A virtue ethics would be truer to the Johnstonian philosophical project than a formal ethics of argument. Resume. (shrink)