Argument to moderation

Argument to moderation (Latin: argumentum ad temperantiam)—also known as [argument from] middle ground, false compromise, gray fallacy, and the golden mean fallacy—is an informal fallacy which asserts that the truth must be found as a compromise between two opposite positions.

An example of the argument to moderation would be to regard two opposed arguments - one person saying that slavery is always wrong, while another believes it to be legitimate - and conclude that the truth must therefore lie somewhere in between.