I'm curious as to what the rationale was, and who the idea occurred to, for the ¬ symbol. I'll grant that more common mathematical symbols like +, −, × and ÷ are also likely unknown, but they seem to vaguely relate to their meaning in an onomatopoetic sense, or are at least clearly derived from the next-simplest related operation (like × to +). Even in set theory, ∪ denotes union—fair enough, probably from a language that began the word with "u"—and ∩ denotes intersection, its logical opposite hence upside-down. Even conjunction and disjunction (∧, ∨) seem to derive from this standard.
After all of that, I have to admit, for "¬" to imply predicate-negation makes no intrinsic sense to me. When I first saw the symbol in college, even as a philomath, I had absolutely no idea what it was trying to say to me.
Does anyone know where it originated and why?