Oh, Internet, why do you abuse Aristotle so?
This has been bouncing around lately with the hashtag #Aristotle
Like many of the fake-istotle quotes, this one can be googled out of existence in about 5 seconds. According to wikiquote, this was first attributed to Aristotle by Lowell L. Bennion in his Religion and the Pursuit of Truth 1989, 52). They suggest that it is a misunderstanding of Nicomachean Ethics 1094b24. The density of the passage provides some grounds for why it may have been (over)simplified. But since it stands so early at the beginning of the Ethics, I suspect that there was a kind of smash and run search for an authoritative sounding quotation. As a side note, there is an interesting–by which I mean crazy–discussion of what this fake quote might mean on Quora. Some of the content there is interesting and accurate (about the idea of the fake quotation, not the actual bit); other parts are like Ancient Aliens crazy.
Aristotle, Nicomachean Ethics, 1 1094a24-1095a
“It is right that we ask [people] to accept each of the things which are said in the same way: for it is the mark of an educated person to search for the same kind of clarity in each topic to the extent that the nature of the matter accepts it. For it is similar to expect a mathematician to speak persuasively or for an orator to furnish clear proofs!
Each person judges well what they know and is thus a good critic of those things. For each thing in specific, someone must be educated [to be a critic]; to [be a critic in general] one must be educated about everything.”
τὸν αὐτὸν δὴ τρόπον καὶ ἀποδέχεσθαι χρεὼν ἕκαστα τῶν λεγομένων· πεπαιδευομένου γάρ ἐστιν ἐπὶ τοσοῦτον τἀκριβὲς ἐπιζητεῖν καθ’ ἕκαστον γένος, ἐφ’ ὅσον ἡ τοῦ πράγματος φύσις ἐπιδέχεται· παραπλήσιον γὰρ φαίνεται μαθηματικοῦ τε πιθανολογοῦντος ἀποδέχεσθαι καὶ ῥητορικὸν ἀποδείξεις ἀπαιτεῖν. ἕκαστος δὲ κρίνει καλῶς ἃ γινώσκει, καὶ τούτων ἐστὶν ἀγαθὸς κριτής. καθ’ ἕκαστον μὲν ἄρα ὁ πεπαιδευμένος, ἁπλῶς δ’ ὁ περὶ πᾶν πεπαιδευμένος.