Definition
The sophists were a loose category of professional teachers active in the Greek world from roughly the mid-5th century BCE, most prominently in democratic Athens. They taught a curriculum centred on aretē (excellence in public life) — and, above all, on rhetoric, the practical art of arguing persuasively in assembly and court. The major figures included Protagoras, Gorgias, Hippias, Prodicus, and (in a slightly different vein) Isocrates. They charged fees, which was novel and resented, and they travelled between cities, which made them outsiders in a polis that prized citizenship.
Their reputation was largely fixed by their opponents. Plato in particular treated 'sophist' as an insult, portraying them as relativists who could make the weaker argument appear the stronger, indifferent to truth, dangerous to the youth. Aristotle was more nuanced but still distinguished true rhetoric from sophistic. The result is that 'sophistry' became the standard English word for clever-but-dishonest argument, even though much of the sophists' actual teaching survives only in fragments and through the filter of hostile witnesses.
Why it matters
How it works
The sophistic teaching method centred on antilogiae — paired speeches arguing opposite sides of the same question, to train the student in seeing how any case could be made. From Protagoras came the famous thesis that the human being is the measure of all things: a position that, depending on reading, is either a sober reminder of perspective or a thoroughgoing relativism. Gorgias's surviving Encomium of Helen defends the most blamed woman in Greek myth as a feat of rhetorical virtuosity, displaying the genre at full power.
The sophists' lasting contribution is the demonstration that rhetoric can be taught — that public eloquence is not a gift of birth but a craft built from technique. Their lasting liability is the suspicion, never fully laid to rest, that the same techniques can serve truth and falsehood with equal ease.