Lorenzo Valla (1407-1457) ranks among the greatest scholars and thinkers of the Renaissance. He secured lasting fame for his brilliant critical skills, most famously in his exposure of the "Donation of Constantine," the forged document upon which the papacy based claims to political power. Lesser known in the English-speaking world is Valla's work in the philosophy of language--the basis of his reputation as the greatest philosopher of the humanist movement.

Dialectical Disputations, translated here for the first time into any modern language, is his principal contribution...