SOPHISTS, the name given by the Greeks about the middle of the 5th century B.C. to certain teachers of a superior grade who, distinguishing themselves from philosophers on the one hand and from artists and craftsmen on the other, claimed to prepare their pupils, not for any particular study or profession, but for civic life (o-o4ncrris, literally, man of wisdom). For nearly a hundred years the sophists held almost a monopoly of general or liberal education. Yet, within the limits of the profession, there was con siderable diversity both of theory and of practice. Four principal varieties are distinguishable, and may be described as the sophis tries of culture, of rhetoric, of politics and of "eristic," i.e., dis putation. Each of these predominated in its turn, though not to the exclusion of others, the sophistry of culture beginning about 447, and leading to the sophistry of eristic, and the sophistry of rhetoric taking root in central Greece about 427, and merging in the sophistry of politics. Further, since Socrates and the Socratics were educators, they too might be, and in general were, regarded as sophists; but, as they conceived truth—so far as it was attainable—rather than success in life, in the law court, in the assembly or in debate, to be the right end of intellectual effort, they were at variance with their rivals, and are commonly ranked by historians, not with the sophists, who confessedly despaired of knowledge, but with the philosophers, who, however unavailingly, continued to seek it. With the establishment of the great philosophical schools—first, of the Academy, next of the Lyceum—the philosophers took the place of the sophists as the educators of Greece.
The sophistical movement was then, primarily, an attempt to provide a general or liberal education which should supplement the customary instruction in reading, writing, gymnastics and music. But, as the sophists of the first period chose for their instruments grammar, style, literature and oratory, while those of the second and third developments were professed rhetoricians, sophistry exercised an important influence upon literature. Then again, as the movement, taking its rise in the philosophical ag nosticism which grew out of the early physical systems, was itself persistently sceptical, sophistry may be regarded as an interlude in the history of philosophy. Finally, the practice of rhetoric and eristic, which presently became prominent in sophistical teaching, had, or at any rate seemed to have, a mischievous effect upon conduct; and the charge of seeking, whether in exposition or in debate, not truth but victory—which charge was impressively urged against the sophists by Plato—grew into an accusation of holding and teaching immoral and unsocial doctrines, and in our own day has been the subject of eager controversy.
But, when Heraclitus to the assumption of fire as the single material cause added the doctrine that all things are in perpetual flux, he found himself obliged to admit that things cannot be known. Thus, though, in so far as he asserted his fundamental doctrine without doubt or qualification, he was a dogmatist, in all else he was a sceptic. Again, the Eleatic Parmenides, deriving from the theologian Xenophanes the distinction between and 64a, conceived that, whilst the One exists and is the object of knowledge, the Multiplicity of things becomes and is the object of opinion ; but, when his successor Zeno provided the system with a logic, the consistent application of that logic resolved the funda mental doctrine into the single proposition "One is One," or, more exactly, into the single identity "One One." Thus Eleaticism, though professedly dogmatic, was inconsistent in its theory of the One and its attributes, and openly sceptical in regard to the world of nature. Lastly, the philosophers of the second physical suc cession—Empedocles, Anaxagoras, Leucippus—not directly attack ing the great mystery of the One and the Many, but in virtue of a scientific instinct approaching it through the investigation of phenomena, were brought by their study of sensation to per ceive and to proclaim the inadequacy of the organs of sense. Thus they too, despite their air of dogmatism, were in effect scep tics. In short, from different standpoints, the three philosophical successions had devised systems which were in reality sceptical, though they had none of them recognized the sceptical inference. Towards the middle of the 5th century, however, Protagoras of Abdera, taking account of the teaching of the first, and pos sibly of the second, of the physical successions, and Gorgias of Leontini, starting from the teaching of the metaphysical suc cession of Elea, drew that sceptical inference from which the philosophers had shrunk. If, argued Protagoras in a treatise entitled Truth, all things are in flux, so that sensation is subjec tive, it follows that "Man is the measure of all things, of what is, that it is, and of what is not, that is not"; in other words, there is no such thing as objective truth. Similarly, Gorgias, in a work On Nature, or on the Nonent, maintained (a) that nothing is, (b) that, if anything is, it cannot be known, (c) that, if anything is and can be known, it cannot be expressed in speech; and the summaries which have been preserved by Sextus Empiricus (Adv.