How did Plato’s attacks help give the word sophist a negative meaning?

Plato’s philosophical attacks were instrumental in shifting the meaning of the term sophist from its original sense of a "wise" or "skilled man" to its modern, negative connotation of a "captious or fallacious reasoner or quibbler".1

Plato and his student Aristotle fundamentally altered the term's perception by claiming that professional teachers, such as Protagoras, were not genuinely seeking truth. Instead, Plato argued that these teachers prioritized victory in debate over truth, frequently employing "eristic"—arguments aimed solely at winning—and "antilogic," which he viewed as a mechanical method to negate any proposition.12

By characterizing the Sophists as individuals who used dishonest means to silence opponents and lacked a sincere regard for truth, Plato successfully framed them as anti-philosophical. This hostile judgment, which often equated Sophistic methods with intellectual dishonesty, became the dominant historical view, leading many to label them as charlatans who corrupted the moral fiber of Greece. While modern scholars have reevaluated these claims, Plato’s influence remains the primary reason the term carries a pejorative weight today.21