Why is the tradition that Parmenides invented logic considered a legend?

The tradition that the Greek philosopher Parmenides invented logic is considered a legend because it conflates the use of argumentation with the systematic study of it. While Parmenides was the first philosopher to employ extended arguments to support his views rather than simply presenting a vision of reality, he never formulated or studied the principles of argumentation in their own right.1

There is no evidence that Parmenides was aware of the implicit rules of inference he utilized. In contrast, the systematic study of logic is credited to Aristotle, who established a formal system of rules and strategies for reasoning. While Parmenides' work may have influenced later thinkers—such as his disciple Zeno of Elea, who utilized the reductio ad absurdum method—the historical consensus remains that Parmenides did not engage in the formal, theoretical analysis that defines the discipline of logic.21