The basic premise of minds as being independent from physical brains is desperate fantasy in any case.
I recognize the following example is extreme, but it does fit the bill: in the past years, we've had many people come forward claiming they were sexually assaulted by various powerful people decades prior. Now, I have not been sexually assaulted, but I understand that a certain portion of the population has been. While you and I did not observe those assaults, we still accept as true what these people are claiming without dismissing or disbelieving them.
My point is: society accepts testimony as evidence for things the judge and jury has not seen. Testimony from one witness is the minimum, and corroborating evidence from multiple sources will indicate something is occurring. I am generally inclined to dismiss claims of conspiracy in these cases, so I must accept their claims as true. Of both the original scenario and the one above, from a purely scientific perspective, it's difficult to lend credence to one and not the other.
We cannot confirm which reality is real. The drug induced experiences or the reality you experience while sober. However when you talk to sober people they describe a reality that is consistent. A shared consistent reality with concreteness. All other descriptions are inconsistent. This man's experience is inexact and will no doubt be very different from what another man experiences when high on some drug.
Bet on the shared consistent experience. Science and logic and common sense is the shared and consistent reality and these things point to man whose brain cells and judgement have been compromised by drugs. You don't even trust a man high in drugs to drive, you gonna trust his judgement about reality itself? Don't be stupid.
I'm now thinking of a society where the majority of people consume a variety of substances which impair their perception of reality. In that scenario, the majority of people believe their interpretation of reality is true. The unimpaired knows those people are incorrect, but the impaired don't know better.
But this case creates a potentially uncomfortable situation for us. If some substances impair, what's not to say other substances enhance? If we know both performance-enhancing and performance-inhibiting substances exist, it stands to reason that both perception-enhancing and perception-inhibiting substances also exist. We know the latter exists, and our primary issue is that it's presently claimed the former does not. A performance-enhancing substance allows an athlete to perform beyond normal limits, and it stands to reason a perception-enhancing drug would do similarly.
However, what if a group of people are under the influence of an identical substance and, at the same time, observe real things which the "unimpaired" do not? The tricky word in the previous sentence is "real": what is real depends on your vantage point. The shadow of a cylinder may be either a rectangle or circle; to only debate the difference between which shadow is "real" obscures the true nature of the illuminated object.
So, a line of scientific inquiry may be the following: is it possible for a mind-altering substance modify an observer's vantage point of the universe? In a more illustrative framing, can a person in Plato's Cave eat something to see beyond their slice of reality? I don't know, but I believe the question is worth consideration.
The key metric here to recognize is consistency. You give a thousand people psychedelics how consistent are there observations? Does every man describe the same thing? In addition how clear and exact are their observations?
Science and logic described by normal sober people is more consistent and more exact then the reality described by people on psychedelics. People who are sober generally agree on the basic principles of logic and mathematics. Consistent consensus is the diffentiating factor.
Additionally which drug better enhances the mind? Cocaine? Heroin? Bleach? Whose to say one experience under one drug is more enhanced than the other? This world described by drugs is cloudy and inconsistent not only among individuals but also across your drug of choice. So you not only have different descriptions of reality from different people, but different descriptions when they use a different drug. Which reality do I trust?
Trust in the consistent description of reality. It's the best bet in my opinion. But of course this also a personal choice.
No. I'd believe another person if they _credibly_ demonstrate that useful information was conveyed to them from sprits. The more people demonstrate this, the more I'll believe it.
In general, the more extreme the claim is, the better evidence I require to believe it. To put it in concrete terms: Given N reports of 2 different kinds of claims, I'd sooner believe that Harvey Weinstein is a sex pest than we made contact with interdimensional spirit entities.
Now, whether such revelations would have satisfied the Skeptical Inquirer crowd is another question.
It would be interesting if that crowd actually did some serious studies of psychedelic revelations, and doubly interesting if they themselves took strong doses psychedelics as part of the study, as psychedelics have a habit of making true believers even out of skeptics, and I suspect many of these skeptics would be a lot less skeptical after taking them... though that'll probably never happen on a large scale as many of them are really not as open-minded as they like to pretend, or are afraid of either losing their "objectivity" or their mind (not completely unfounded fears).