aporia (n.)

1580s, in rhetoric, "professed doubt as to where to begin," from Latin, from Greek aporia "difficulty, perplexity, want of means, poverty," abstract noun from aporos "impassable, impracticable, very difficult; hard to deal with; at a loss," from a- "not, without" (see a- (3)) + poros "passage" (from PIE root *per- (2) "to lead, pass over"). Meaning "equality of reasons for or against" is by 1893.