The chapter argues that the antecedents of Greek philosophical interest in logical argumentation can be found in the late-fifth-century sophistical practice and teaching of technê logôn or “the art of arguments.” It assembles the extant evidence for the teaching of technê logôn by figures such as Protagoras, Gorgias, Antisthenes, Antiphon, Prodicus, Socrates, and the author of the Dissoi Logoi. Original and provocative features of technê logôn taught by these figures include: (i) the ability to produce opposing arguments on both sides of any question (antilogiai); (ii) the ability to refute any given position or argument; (iii) the ability to skillfully question another person, or to answer such questioning, on any topic; and (iv) the subject-neutral ability to produce arguments on any subject. These features would later become important elements in what fourth-century philosophers would call “dialectic,” “rhetoric,” and other successors to the fifth century “art of argument.”