Every crank is a visionary, but not every visionary is a crank. Some visionaries prove to be prophets and seers. Some have ideas that are bogus. Due to the nat

Every crank is a visionary, but not every visionary is a crank. Some visionaries prove to be prophets and seers. Some have ideas that are bogus. Due to the nature of visionary ideas, this is most of the time unknown -- e.g. Julian Jaynes's bicameral mind. A crank is a visionary whose ideas are knowably bogus: e.g. Rupert Sheldrake. (A charlatan is unlike a crank because he has no idee fixe, no vision -- he moves opportunistically. A conspiracist is similarly unlike a crank because it bites at anything that moves.) Whether Ted Nelson is a crank is left as an exercise for the reader.