Hard to understand what this might mean.
Is it that Plato presents the *dramatic character* Thrasymachus as offering arguments distorting those expressed by the *historical* Thrasymachus, much as Aristophanes's *dramatic character* Sokrates (in the *Clouds*) offers arguments distorting those expressed by the *historical* Sokrates?
But then, how can this be maintained when we have, AFAIK, no other record of the actual views of Thrasymachus than what Plato presented in his philosophical drama?
Or is it that Cox is confusing the *dramatic character* Sokrates with the *historical* Plato and suggesting that in the course of the Book I dialectic "Sokrates"/Plato is distorting the argument presented by "Thrasymachus?" This might be an interesting approach, were he to state clearly what those "distortions" are, how "Thrasymachus" should have answered "Sokrates"'s distortions, and how "Sokrates" could have responded to "Thrasymachus"'s answers. But that would be doing Philosophy.
Shane Mage
"This cosmos did none of gods or men make, but it always was and is and shall be: an everlasting fire, kindling in measures and going out in measures."
Herakleitos of Ephesos, fr. 30