In general, evidence could be anything, though evidence that’s inherently personal only applies to the experiencer.

Some existential categories of ours:

• Mind (self): qualia, (phenomenological) experiences, love, headaches, feelings, dreams, hallucinations, thinking (like this analysis perhaps), …
  
  • It’s not possible for me to have your headaches; someone appearing in another’s dream aren’t affected by that; imagining slapping someone doesn’t bruise them; etc. This is the kind we may talk about (linguistics) or similarly express to each other. Since they’re inherently part of the experiencer, i.e. the experiencer’s (ontological) self-identity, they’re the kind whose mere existence are rather hard for the experiencer to doubt (cf the cogito, self-knowledge).
• Extra-self: the perceived, other people, sunrise, (Moon) rocks, galaxies, objects, bones, cells, buoyancy, gravity, soccer games, “physicalities”, …
  
  • This, on the other hand, is more the kind we can show each other, perhaps point at, though of course also talk about. The kind that shows the larger world we all share, inhabit and are parts of, embedded in, that feeds us. Perceiving involves experiences themselves (the mind (self) category) and the perceived (this category, the extra-self).

Categories of existential justification more or less following the above:

• Deduction (logicing)
• Phenomenological (self, experiential) — mind (self) above
  
  • Say, if you claim to have a headache, then I’d likely believe you (without further justification or fMRI scans). Not because you can readily show me your headache, or that I can experience your headache, it’s part of you, not something other than you. But you may still have a headache, and can express that (linguistics).
• Empirical (evidence, observations) — extra-self above
  
  • Justifying the existence of the Sun wouldn’t be particularly difficult. That bright thing in the sky that warms things up and powers photosynthesis, whatever it all may be exactly. Often we don’t need to involve a word or label to justify existence, but can instead show. (Note, this analysis is expressed in writing.)

By this categorization,

• hallucination is mistaking identity for non-identity, and
• solipsism is mistaking non-identity for identity.

A significant difference between hallucination and perception is the perceived. Self-externalization of purely phenomenological experiences is an error among many others, all of which is relevant for assessing knowledge claims. Reports of the numinous, “the wholly other”, can (much like substance dualism) also be charged with the interaction problem. This analysis accounts for and adequately explains the problem of inconsistent revelations.


“The Sleep of Reason Produces Monsters” (1799) by Francisco Goya (1746-1828)