In this paper I examine the relationship between the natural philosophers and the sophists in Met N 3-6, as well as Aristotle's strategies for refuting them: persuasion and coercion. Firstly I analyze the taxonomy of the opponents of the PNC, where I consider three moments. Then I suggest a distinction that Aristotle seems to have in mind between a genuine, real, aporia and a superfluous one. On this basis I try to illuminate the final step of the taxonomy (Met. N 6, 1011a3-8), where the natural philosophers and sophists are close to each other. Despite their differences, both, according to Aristotle, pose problems which could be solved easily by simply resorting to the obvious. Finally I try to clarify the kind of strategy proposed in defence of the PNC by appealing to sonic remarks on the search for truth in Met II.