Evidentiality And Supposability

Today I'm thinking about markers of evidentiality in grammar. I think I like a system that marks five sources of evidence: perceptive, deductive, inductive, quotative, and intuitive. Also, I like simultaneously distinguishing whether the speaker finds the statement informed by one of those sources to be plausible or implausible.

For clarity, here are some corresponding adverbs of evidentiality for the system I like:

Perceptive: noticeably, manifestly
Weak perceptive: seemingly

Deductive: logically
Weak deductive: theoretically, speculatively, hypothetically

Inductive: reasonably
Weak inductive: presumably

Quotative: reportedly
Weak quotative: allegedly, anecdotally

Intuitive: innately, subconsciously,
Weak intuitive: unconsciously, oneirically, allegorically, fictionally, head-canonically

I also tried to work out where supernatural evidential adverbs would fall among these evidential sources for people in universes with gods. Perhaps the adverb "prophetically" would be perceptive, "inspired divinely" would be intuitive, "kabbalistically" would be deductive, "theologically" would be inductive, and "esoterically" would be quotative. I dunno; for me, they're all mistaken identifications of weak intuition.

The adverb "supposedly" is an interesting case. I'd like to use it to name weak inferential evidentiality ("we could suppose"), but in common practice, it's used as a weak quotative ("I've heard but don't strongly believe"). I don't think "supposedly" is even used to indicate that the reported claim came from people who were supposing; the word just has a weird usage that is deviating from its root, with no cognitive action of supposition indicated.

However! I think the non-standard word "supposably" *does* primarily have the first meaning, "could be supposed". It marks a different evidentiality! Whoever wrote the wiktionary page for "supposably" also seems to agree with me. It would be nice if we all could admit that "supposably" is its own word with a different meaning and stop telling people to use "supposedly" when they're not informing us of a dubitative quotation. But if not, "presumably" is still a fine adverb for the weak inferential.