Who are the main anti-realists about higher-order vagueness? Would Crispin Wright be one? And, if so, is he a universal or partial anti-realist?
Crispin Wright in fact denies higher-order vagueness. In that sense he's an anti-realist about that notion. See his recent paper 'The Illusion of Higher-Order Vagueness':
But what does it mean to be a partial versus a universal anti-realist?