How did Protagoras’s claim that “man is the measure of all things” encourage relativism?

Protagoras’s claim that “man is the measure of all things” encouraged relativism by asserting that the world is defined by how it appears to the individual rather than by an objective, universal reality.123

By suggesting that no views are ultimately or objectively true, Protagoras implied that all perceptions and judgments are relative to the person experiencing them. He illustrated this by noting that if a person feels cold, it is objectively "cold" for them, regardless of external conditions; therefore, the world is simply what it appears to be for each human being. This perspective challenged the philosophical tradition of seeking a "real" world distinct from the phenomenal world, leading to the conclusion that knowledge is subjective and that there is no single, absolute standard for truth. Consequently, this stance fostered a skeptical view where each person's opinion holds equal validity, effectively undermining the possibility of discovering permanent, unchangeable truths.1423