Contrastivism, or the contrast theory of meaning is an epistemological theory proposed by Jonathan Schaffer that suggests that knowledge attributions have a ternary structure of the form ‘S knows that p rather than q’. (source: Wikipedia)
In regard to Free Will debate, both Compatibilist and Non-compatibilist are right in contrast to a certain position. Compatibilist are right if we talking about freedom from constraints, while Non-compatibilist are right if we are considering freedom from causation.
We can never know whether we are living in a Matrix or not (Skeptic is right), but we do know a lot of things by contrasting them. For instance, I know I am writing this on a blog, not a paper.