Via, Rotten Chestnuts, a summation of scholar David Stove’s essay “Idealism, A Victorian Horror Story”. Apparently, everything the Left has believed for the last century and a half comes from the perception/things-in-themselves fallacy, which allows all the other word games to follow.
Since you’re starting from a tautology, thanks to the miracle of Dialectics you can say whatever you want. There’s no cognitive dissonance, because there’s no cognition at all. It all arrives at the same point — whatever degraded version of Idealism your victim group is pushing. As Stove says, all you need for a Gem is tautology in the premise, Idealism in the conclusion, and pomposity throughout. Berkeley to Hegel to Marx to Derrida, the Left’s entire intellectual genealogy in four steps.