Can you tell me why English infinitives have "to" in front of them?
I've never met anyone, anywhere who knew. It isn't inherent in the language -- Old English doesn't do it. As far as I can figure, it confers some idea of futurity, rather like the "to" in tomorrow or tonight. And the original form of those words often appeared as to-morrow and to-night as if the *to- was some sort of archaic enclitic, but I'm not aware of that form appearing anywhere else. Clearly, its function is purely grammatical, as that form of "to" carries none of the locative or dative functioning the preposition to has.