"or" vs. "nor"
I can't understand why the following sentece use "nor" instead of "or"

- He is neither pessimistic nor optimistic about his prospects for the future.

Could anyone explain me? Thanks you :)

Question

"or" vs. "nor"
I can't understand why the following sentece use "nor" instead of "or"

- He is neither pessimistic nor optimistic about his prospects for the future.

Could anyone explain me? Thanks you :)

Answer

It's quite simple. The pairing is 'either..or' for positive options and 'neither... nor' for negative. Either X or Y.  Neither X nor Y. You can't mix them up.    Does that make sense?