The most interesting and influential thinker in the fifth century was Socrates, whose dedication to careful reasoning transformed the entire enterprise since he sought genuine knowledge rather than mere victory over an opponent. Socrates employed the same logical trick, developed by the Sophists to a new purpose, the pursuit of truth. Thus, his willingness to call everything into question and his determination to accept nothing less than an adequate account of the nature of things made him the first clear exponent of critical philosophy. One o ....