Abstract
By considering the epistemology and relations among certain philosophical problems, I argue for a disjunctive thesis: either (1) it is highly probable that there are (i) several (ii) mutually independent philosophical reductios of highly commonsensical propositions that are successful—so several aspects of philosophy have succeeded at refuting common sense—or (2) there is enough hidden semantic structure in even simple sentences of natural language to make philosophers highly unreliable at spotting deductive validity in some of the simplest cases—so we are much worse at logic than we think and cannot, in general, know when our own arguments are valid. The untoward consequences of each disjunct are explained.