[jrflowers]

I like this because it immediately accounts for truth not arrived at though reason and then just slaps on the word “universal” as the descriptor for the subset of truth reachable through reason. It is convincing because universal is a big word

[bowsamic]

Well the reasonable truth is not universal as in exhaustive but as in it always holds. I mean universal as in necessary, not contingent. Psychedelic and personal experience is merely contingent

[jancsika]

At least for human affairs, there's more to it than that.

For example, we don't only care about humans having an understanding of, say, a moral choice. We also care about whether or not a given human can/will make a moral choice.

The latter happens in a different part of the brain. Sharpening one's teeth on the mere understanding of a moral truth is unlikely to improve one's ability to carry out even a well-understood moral act if that same person doesn't have experience doing it. On the other hand, personal experience-- say, with a mentor from a similar background, or even just grooming horses with a group of similarly cantankerous teens while talking about their feelings-- can sharpen a person's ability to make that moral choice, even on a consistent basis.

I'm not a fan of psychedelics, but people have told me they were instrumental in guiding them to make better choices-- sometimes choices that they knew were right but couldn't bring themselves to make.

It is of course totally reasonable to categorize all of this-- neurology, human self-knowledge, behavior, and socialization-- under the heading of reasonable truth. But for some reason, HN fans of reason of generally exclude it. So when you say, "The truth is fully accessible through reason," I agree in this larger sense. But the larger sense isn't the common usage, so it's often easier to just say you're wrong. :)

Edit: clarification