Why Mereological Anti-Conservatism Is No Better Than Conservatism

Abstract Declos and Grandjean (2025) have introduced Mereological Anti-Conservatism as a new answer to the Special Composition Question. According to this view, extraordinary composite objects like fusions of trouts and turkeys exist, whereas ordinary objects like trouts and turkeys do not. Their aim is not to defend this bizarre ontology but to argue that it is, surprisingly, more plausible than Conservatism, according to which only ordinary composites exist. They claim that Anti-Conservatism avoids the problems of vagueness, change, and common sense that afflict Conservatism, and that, modally, it is more epistemically inclusive, counting more possible worlds as ontologically correct. I argue that this comparative assessment fails: the view’s alleged advantages concerning vagueness, change, and common sense do not hold, and the modal argument they advance rests on a faulty assumption about infinite cardinalities and an uneven application of evaluative criteria.