Semantic arguments are dangerous but... > is perfectly grammatical, whereas "to beg the question" isn't, because the direct object of "to beg" has to be an age

Semantic arguments are dangerous but... > is perfectly grammatical, whereas "to beg the question" isn't, because the direct object of "to beg" has to be an agent which can grant a wish Wish-granting-agency is not a grammatical category of English nouns. The problem is a semantic error, not a grammatical one. "Colorless green ideas sleep furiously." is famously perfectly grammatical but semantically nonsense.