The crucial question of burden of proof

There is much misunderstanding concerning who has the responsibility of providing evidence when making a claim

Cosmic Entity by Jason Nguyen, image from pinterest.com.

[See here for a related essay on the topic of burden of proof.]

Not long ago I was spending a few minutes on the Notes feature of Substack, which pretty much works like an internal Twitter. Unlike that latter infamous platform, though, the level of discussion on Notes is significantly higher, probably because it is populated by people who either pay to be there or at the very least are genuinely interested in following a number of favorite writers.

Anyway, one of the posts that kept showing up on my Home feed concerned “experiments” with psychedelic drugs. I have to admit that I am pretty skeptical of the use of any mind-altering substance beyond very minimum levels. That’s because Stoics value very much the integrity of their faculty of judgment, which is impaired by definition when your mind is artificially altered. That’s why the commentator Diogenes Laertius famously said:

“[The Stoics] will drink in moderation, but will never get drunk.” (VII.118)

Nevertheless, if someone wishes to experience drug-induced hallucinations, that’s their business and I am certainly not here to judge them. But some of these people go far beyond that, actually claiming to be “psychonauts,” that is explorers of a different, yet objectively existing reality that they can, somehow, access by smoking sufficient quantities of N,N-Dimethyltryptamine (DMT), sometimes dubbed “The Spirit Molecule.”

Psychonauts get a boost by notorious cranks like Jordan Peterson (check out one of his “Peterson clips” with Dennis McKenna, for a sample), who believes in Carl Jung’s concept of a collective unconscious. Never mind that there is no evidence for any such thing as a collective unconscious and that Peterson, following his usual modus operandi, talks a lot while managing to say little, using as many qualifiers and vague terminology as he can muster.

The obvious interpretation of psychonautic entities is that they are hallucinations that reflect users’ personal psychology and experiences, as well as the cultural background in which they grew up. That neatly explains while there is a partial degree of consistency in these experiences, and yet also very obviously a detectable cultural component to them. Moreover, you know, we are talking about substances that are biologically well characterized as hallucinogenic.

So, as politely and constructively as I could, I pushed back on Notes against what I consider, to use Carl Sagan’s famous phrase, extraordinary claims. The typical response I got was: what proof do you have that these entities don’t (objectively) exist? (They clearly do exist in the minimal sense of being some people’s mental creations.)

And that’s when I realized that perhaps another essay on the concept of burden of proof was in order. A number of people on Notes seemed to be under the common misconception that personal experience counts as an almost unbeatable source of evidence, and that therefore the responsibility to provide counter-evidence laid squarely on me.

A more sophisticated objection I have sometimes heard regarding burden of proof goes like this. In formal logic, affirming that p is entirely equivalent to denying that ~p (i.e., the negation of p), so the burden of proof indeed appears to be equally split between the two positions being examined (p and ~p).

This doesn’t apply just to alleged psychedelic entities, of course. It’s an argument advanced also by, for instance, believers in UFOs, which have recently come out of the woodwork again thanks to (in my opinion) misguided Congressional hearings on the subject.

Whenever a skeptic asks a UFO believer about evidence beyond blurry images and unverified or doubtful testimonies, the answer is likely to be: what proof do you have that they don’t exist? Wrong question. Let’s see why.

UFOs on Capitol Hill, image from BBC.

I am certainly not about to reject classical logic, of course. But it does have a number of known limitations, which is why, for instance, it is actually rarely used in science (it’s much more useful in mathematics). Most scientific research relies not on formal deductive logic but on one or more forms of inductive logic, perhaps the best known being inference to the best explanation (IBE), sometimes referred to as abduction (no, not of the UFOs type!).

A great example of IBE is provided by Sir Arthur Conan Doyle’s Sherlock Holmes stories. Despite Holmes often telling Dr. Watson that he uses the method of deduction, he doesn’t. He uses abduction. He collects as much preliminary information as possible, proceeds to formulate a number of plausible alternative hypotheses, then collects more information based on those hypotheses. The process continues until the evidence begins to consistently point in one particular direction (hypothesis) and away from the others. In other words, Holmes infers his conclusions based on which of a number of competing hypotheses best explains the available data. Just like a scientist would do.

Let’s apply IBE to the UFOs question. One hypothesis, of course, is that there have been mysterious visits by highly technologically advanced extraterrestrial beings for at least the past several decades. (The first modern UFO sighting took place on Mount Rainier back in 1947.) A second hypothesis is that the sightings are the result of a number of miscellaneous ordinary causes, including mistakes made by observers, such as misidentifying airplanes, satellites, meteorites, and even the Moon (yup, it has happened!) for spacecrafts, combined with a certain percentage of outright fraud.

There are, of course, additional possibilities, for instance that UFOs are really experimental military aircrafts, but let’s focus on the first two options for the sake of argument. Once we take into consideration the available evidence and, crucially, our pertinent background knowledge about things like space travel, astronomical distances, likelihood of human mistakes, implausibility of extraterrestrials visiting without doing anything other than the occasional anal probing, and so forth, IBE strongly points toward non extraterrestrial explanations for UFO sightings. If this is correct, then the burden of proof is squarely on those making the claim of extraterrestrial visits. Such burden could be met in a variety of ways, for instance by producing an actual crashed flying saucer, or actual bodies of real aliens, or any other artifact beyond blurry or obviously fake photos.

Notice an important point here: if our background knowledge were different, the burden of proof may be reversed. Suppose we actually lived in a world where we somehow knew for certain of the existence of multiple technological civilizations in the immediate star neighborhood of our sun; or science had discovered that interstellar flight is actually a piece of cake. Then it would behoove us to take a really close look at even the fuzzy pictures, because the a priori likelihood of visits would then be much higher.

Sherlock Holmes talks to Dr. Watson, Strand magazine. Image from Wikimedia.

Something like that goes for psychonautics as well. The reason I think skepticism is warranted and the burden of proof is on the psychonauts is because of our background knowledge about how the brain functions, and how it is affected by psychoactive substances such as DMT. If we lived in a world where these substances were known to act differently, and we had any serious reason to think that “other dimensions” really exist, then we ought to take the alleged entities more seriously. But we don’t live in that world, so we don’t take them seriously.

This, incidentally, does not mean that I am absolutely certain that UFOs are not actually extraterrestrial spaceships, or that psychedelic entities do not objectively exist in a parallel dimension. Unlike deductive logic, induction does not lead to certainty. In fact, as I’ve argued before, certainty is just not a thing as far as human epistemology is concerned. And that’s another important difference between a skeptic and a True Believer: skeptics are comfortable with tentative, probabilistic answers, while True Believers seek the Truth. Sorry folks, but that’s a fool’s errand.

One last point. As a skeptic I have always maintained that a major reason to counter erroneous beliefs is that they have a nasty tendency to spread beyond the original point of departure. If you believe in one conspiracy theory you are more likely to believe in another. If you believe in UFOs you are more likely to believe in paranormal phenomena, and so forth.

Along similar lines, a recent study published in the premier scientific magazine Nature investigated whether using psychedelic drugs alters a person’s metaphysical beliefs in the long term. It does:

“Results revealed significant shifts away from ‘physicalist’ or ‘materialist’ views, and towards panpsychism and fatalism, post use.”

Now, some may hail this as good news. Down with physical-materialism! Hurrah for panpsychism! [1] But the fact is that physical-materialism is not only the most sensible metaphysical position one can take nowadays, but also very much in alignment with the findings of modern science, especially fundamental physics. Indeed, it is the most sensible metaphysical position largely because it aligns with modern science (where else would you get your metaphysics?).

Panpsychism and other metaphysical accounts of reality, by contrast, are either internally problematic (i.e., incoherent), contradicted by the available evidence, or both. If taking drugs messes with your brain to the point that you begin to change your mind about the very nature of reality even when you are not using them I submit that you may have a problem. Please throw away the psychedelic kit and come back to the real world. It’s more than enough fun out here.

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[1] Panpsychism refers to a family of views that mind-like phenomena are fundamental to the structure of the universe, despite modern physics finding no place for such phenomena.