Platonic dialectic & knowledge-trivialization
In Platonic dialectic as I currently see it, arguments typically regarded as directly asserting the existence of X are often actually taking (roughly) the form, “If you adopt a theory (an ontology, a semantics, an epistemology, etc.) much simpler than one that includes X or equivalent, you wind up trivializing knowledge.” That these would be arguments against trivialization distinguishes them importantly, I think, from transcendental arguments, which are typically concerned to show the possibility of knowledge in a more positive sense. (It would be interesting to know whether my contrast is based in an insufficiently-uncharitable reading of the transcendental tradition.)
Edit (3/4/2017): Though it’s not what I had in mind, it occurs to me that Meno’s paradox may be able to be seen in this way, that is, as a particularly striking trivialization by identification of the initial and terminal objects of thinking.