Aristotle says only someone who has been well brought up can be "a competent student of the Right and Just, and in short of the topics of Politics in general" (Nic. Eth. 1095b). And I believe he somewhere says, similarly, that you cannot argue rationally with (or, perhaps cannot teach logic to) someone who is willing to maintain a contradiction. But I do not find that passage.
Is such a claim about contradiction found in what we have of Aristotle?