According to the revised Bradley’s Arnold (p.99):
The > imperfect > and pluperfect tenses denote > what would be happening > or would have happened if some imagined condition of the past were being fulfilled. > The reference of the imperfect is generally to the present, > that of the pluperfect to the past.
(si facias), pecces
(if you should do it), you would sin
(si faceres), peccares. (if you were doing it), you would be sinning.
(si fecisses), peccavisses. (if you had done it), you would have sinned.
However, A&G and many other authorities translate the imperfect with “would have”:
Woodcock, A New Latin Syntax, p. 91:
The imperfect potential subjunctive expresses the speaker’s or writer’s opinion as to what was likely to happen in the past, i.e. what could have or might have happened.
The phrase from Livy,
crēderēs eōs bonōs esse
could be translated either way, and I’ve seen both (you would believe/you would have believed)
Same with this from Horace:
hīc, ubi nunc fora sunt, lintrēs errāre vidērēs
you would see/would have seen boats
What about this from Cicero:
quis umquam crederet mulierum adversarium Verrem futurum [esse]?
This seems to only work with “would have:”
“who would ever have been believing that Verrus would be an adversary of women?”
Lastly, another from Cicero which seems to only allow for “would have”:
Cuperem vultum videre tuum, cum haec legeris
I would have liked to have seen your face when you were read this.
The idea expressed in Bradley’s Arnold, that the potential subjunctive is in fact the apodosis of a conditional clause with an unexpressed protasis doesn’t seem to hold up. Instead, there does seem to be some sense of “potential.” Thoughts? Have I missed something? The explanation from Bradley’s Arnold reduces categories, but it just doesn’t seem to work.