Hmm I don't know about your one, but here's a good list of common fallacies in argument: http://www.relativelyinteresting.com/logical-fallacies-collection-30-ways-lose-argument/
It might be a black /white one - suggesting would definitely rather than could have, perhaps? Or exclusion of the middle.

Have you seen the cognative biases diagram where they put everything in a pretty circle? I really like it

https://betterhumans.coach.me/cognitive-bias-cheat-sheet-55a472476b18#.n1gg2c1z2