Basil L. Gildersleeve, Syntax of Classical Greek

The past tenses of the indicative with “ἄν” may denote unreality (the most common use) in such a way that the imperfect denotes opposition to a continued action either in the present or in the past; the aorist denotes opposition to attainment, chiefly in the past, very rarely in the present; and the pluperfect indicative with “ἄν” denotes opposition to completion, more frequently in the present.

Imperfect in opposition to present:

“ἐγὼ γὰρ . . . εἰ μὲν μὴ ᾤμην ἥξειν . . . παρ᾽ ἀνθρώπους τετελευτηκότας ἀμείνους τῶν ἐνθάδε, ἠδίκουν ἂν” [I should be in the wrong (I am not)] “οὐκ ἀγανακτῶν τῷ θανάτῳ”, PLATO , Phaedo, 63

Imperfect in opposition to the past:

“μένειν γὰρ ἐξῆν τῷ κατηγοροῦντι τῶν ἄλλων, εἰ δὲ τοῦτ᾽ ἐποίει ἕκαστος, ἐνίκων ἄν” [they would have been victorious (they were not)], DEM.3.17.

Aorist in opposition to the past:

“εἰ τὸ καὶ τὸ ἐποίησεν ἅνθρωπος, οὐκ ἂν ἀπέθανεν”, DEM.18.243; If the man had done so and so, he would not have died (he did die).

Aorist in opposition to present:

“εἰ μὲν οὖν ἄνθρωπος, ὃν δεῖ πόλλ᾽ ἀκοῦσαι καὶ κακά”, | “αὐτὸς ἦν ἔνδηλος, οὐκ ἂν ἀνδρὸς ἐμνήσθην φίλου” [I should not mention the name of a friend (as I am doing)], AR. Eq. 1276-7.

Pluperfect in opposition to present completion:

“εἰ δέ γε μηδεὶς ἄλλος ἢ Ζεῦξις ἔγραφε, καλῶς ἄν σοι ἀπεκέκριτο”; PLATO, Gorg. 453D; But if there were no other painter than Zeuxis, would your reply hold good?

Pluperfect in opposition to past completion:

“εἰ . . . ὁ ἀνὴρ . . . ἀπέθανεν . . . δικαίως . . . ἂν ἐτεθνήκει”, ANTIPHON, 4, “β”, 3; If the man had been killed, he would have been justly killed (his death would have been justifiable).

For further examples, see Unreal Conditional Sentences.

For “ἐβουλόμην” (“ἤθελον”) “ἄν” with infinitive antithetical to the dependent verb, see 367.