The essays in this collection are written by students, colleagues, and friends of Nuel Belnap to honor him on his sixtieth birthday. Our original plan was to include pieces from fonner students only, but we have deviated from this ever so slightly for a variety of personal and practical reasons. Belnap's research accomplishments are numerous and well known: He has founded (together with Alan Ross Anderson) a whole branch of logic known as "relevance logic." He has made contributions of fundamental importance to the logic of questions. His work in modal logic, fonnal pragmatics, and the theory of truth has been highly influential. And the list goes on. Belnap's accomplishments as a teacher are also distinguished and well known but, by virtue of the essential privacy of the teaching relationship, not so well understood. We would like to reflect a little on what makes him such an outstanding teacher.

"The Summa Theologica is the best-known work of Italian philosopher, scholar, and Dominican friar SAINT THOMAS AQUINAS (1225 1274), widely considered the Catholic Church s greatest theologian. Famously consulted (immediately after the Bible) on religious questions at the Council of Trent, Aquinas s masterpiece has been considered a summary of official Church philosophy ever since. Aquinas considers approximately 10,000 questions on Church doctrine covering the roles and nature of God, man, and Jesus, then lays out objections to Church teachings and systematically confronts each, using Biblical verses, theologians, and philosophers to bolster his arguments. In Volume III, Aquinas addresses: faith and heresy charity peace and war mercy, anger, and justice prayer truth and much more. This massive work of scholarship, spanning five volumes, addresses just about every possible query or argument that any believer or atheist could have, and remains essential, more than seven hundred years after it was written, for clergy, religious historians, and serious students of Catholic thought."

In this rigorous investigation into the logic of truth Anil Gupta and Nuel Belnap explain how the concept of truth works in both ordinary and pathological contexts. The latter include, for instance, contexts that generate Liar Paradox. Their central claim is that truth is a circular concept. In support of this claim they provide a widely applicable theory (the "revision theory") of circular concepts. Under the revision theory, when truth is seen as circular both its ordinary features and its pathological features fall into a simple understandable pattern. The Revision Theory of Truth is unique in placing truth in the context of a general theory of definitions. This theory makes sense of arbitrary systems of mutually interdependent concepts, of which circular concepts, such as truth, are but a special case.