[abustamam]

This appears to be true in a vacuum, but practically it's not for many "truths." For example, we can all agree that the holocaust was an atrocity that should have never happened. Certainly there are folks who don't believe that, or who don't even believe that it ever occurred, but the vast majority of reasonable people would consider those folks irrational (to put it mildly).

Now, I notice that I use "we all agree" and "vast majority," which is no way to explain an objective fact, but what we all agree on as a community or society _is_ reality. A society or community that has a different reality(s) than us is probably not a society or community that we would associate ourselves with.

This operates on several levels and dimensions; the common realities I share with my local Islamic community are different realities than I share with my tech community, or Toastmasters community, or even family.

Going back to the original point, yes, there are no realities that the entire global community can agree on, not even something as seemingly incontroversial as medicine (Christian Science for example https://rpl.hds.harvard.edu/religion-context/case-studies/mi... ), but no individual is part of the global community. We choose our communities based on the realities that we accept to be true.

[Anotheroneagain]

>Now, I notice that I use "we all agree" and "vast majority," which is no way to explain an objective fact, but what we all agree on as a community or society _is_ reality. A society or community that has a different reality(s) than us is probably not a society or community that we would associate ourselves with.

This is literally schizophrenia, when two such communities meet, a massacre inevitably occurs.

[EnigmaFlare]

> or who don't even believe that it ever occurred, but the vast majority of reasonable people would consider those folks irrational

You're confusing rationally concluding something with feeling morally righteous for believing it. It's not irrational to disbelieve something that people only believe because they'll feel like a bad person or be punished for doubting. See religion, for example.

The only reason most people believe the holocaust happened is because they heard about it from general society. Same way they believe God created the world. Almost no layman has actually studied it. It's just a kind of common faith where being a believer is what's important rather than the content of the belief.

I'm not saying it didn't happen, just that the vast majority of believers aren't believing out of rationality but out of indoctrination.

Same is true of all sorts of beliefs in things that don't directly affect us. We believe them because everyone assures us they're true, not because we sat down and worked out the conclusion for ourselves.