Earlier this week Massimo Pigliucci over at Rationally Speaking wrote an intriguing blog post asking whether or not there is a pseudoscience black hole – a point beyond which a pseudoscience gets sucked in and can never escape? Asked from the other direction – are there any historical examples of a pseudoscience that became legitimate, essentially turned out to be true?

I thought this was an interesting enough question to pick up the ball and explore the question further.

First, the question requires a discussion of what is pseudoscience. This is a common topic of discussion among skeptics. Any definition must contend with the demarcation problem – there is no bright line between legitimate science and pseudoscience. Rather, there is a smooth continuum, although I do think the distribution along that continuum is bimodal.

The differences between science and pseudoscience have to do with process, not subject matter. Pseudoscientists display a number of typical behaviors  (I will quickly list some of them here, but I am overdo for an updated post just on this topic):

1 – Hostile to criticism, rather than embracing criticism as a mechanism of self-correction
2 – Works backward from desired results through motivated reasoning
3 – Cherry picks evidence
4 – Relies on low grade evidence when it supports their belief, but will dismiss rigorous evidence if it is inconvenient.
5 – Core principles untested or unproven, often based on single case or anecdote
6 – Utilizes vague, imprecise, or ambiguous terminology, often to mimic technical jargon
7 – Has the trappings of science, but lacks the true methods of science
8 – Invokes conspiracy arguments to explain lack of mainstream acceptance (Galileo syndrome)
9 – Lacks caution and humility by making grandiose claims from flimsy evidence
10 – Practitioners often lack proper training and present that as a virtue as it makes them more “open.”

Even world-class respected mainstream scientists may allow some pseudoscientific behavior to creep in. Further, rank pseudoscientists may be right on certain points or actually produce some useful evidence. One way to restate Massimo’s question is this – is there a point along the spectrum toward pseudoscience beyond which a pseudoscientist cannot return, and if so, approximately where is that point?

When considering individuals, rather than topics, I would say anything is possible. Respected scientists can descend into full pseudoscience later in their careers, with Linus Pauling being the classic example. It’s also possible that a pseudoscientist can see the error of their ways and reject their prior claims, although a dramatic example of this does not come readily to mind.

Massimo’s question was framed more toward the belief rather than the believer – is there any claim that was considered pseudoscience but now is accepted by mainstream science? This is problematic because pseudoscience is defined by its methods, not its claims. So, if pseudoscientists turned out to be correct in the end, it would be almost by pure luck and chance. This is not impossible, people can be right for the wrong reasons.

Is there, however, an event horizon – a point of no return? Again, I think there is a demarcation problem, meaning a fuzzy boundary, and therefore no sharp event horizon. I do think that the longer a claim is rejected as pseudoscience the less likely it is that it happens to be true.

The fun comes in trying to think of examples. Massimo raised the possibility of acupuncture. While I agree that acupuncture has gained a certain amount of mainstream acceptance, this is despite being a pure pseudoscience, not evidence that it is legitimate. In my opinion, acupuncture is merely an example of a sophisticated pseudoscience that does a good job of infiltrating mainstream institutions by camouflaging itself as a real science. When you dig deep, however, there is nothing but pseudoscience.

Acupuncture also raises another problem of categorization, which Massimo discusses. What if acupuncture has some efficacy through a purely physiological mechanism, and all of the pre-scientific explanations about chi and life force are still pseudoscience? Can it then be said that “acupuncture” is not completely pseudoscience?

I say no. This gets to the definition of what is acupuncture, which I contend is placing thin needles into acupuncture points (regardless of the explanation). The evidence shows that acupuncture points do not exist, and that where or even if you stick needles through the skin adds nothing to efficacy. There may be some non-specific effects from superficial or incidental aspects of acupuncture (such as conditioning, or counter-irritation) but this does not rescue acupuncture from being pseudoscience.

As another example of this point, blood letting (phlebotomy) is an accepted treatment for polycythemia (too many red blood cells) and also certain conditions of excess iron. Does this mean that blood-letting as practiced under Galenic medicine is not pseudoscience? Of course not. It is a coincidence that removing blood has very limited clinical applications that have nothing to do with the practice or philosophy of blood-letting.

Massimo also brings up herbalism, and does explore the complexity of this example. Herbalism is complex because it contains many practices and beliefs. Simply stating that herbs are a rich source of potential pharmacological ingredients is accepted science. It is even true that most cultures identified local plants that can be exploited for medicinal or other purposes.

However, many modern examples of herbalism as a system of medicine are pseudoscientific. They are often based on the naturalistic fallacy, or even supernaturalism (stating, for example, that God created herbs specifically to be medicines for Homo sapiens.) Many practices within herbalism are based on anecdotes and tradition, and do not follow any rigorous scientific methodology.

In searching for other examples of pseudosciences that escaped from the gravitational pull of the black hole, other problems of definition arise. To qualify as a “pseudoscience” it is not enough that a claim was not initially accepted. Most scientific ideas begin out on the fringe and are treated with initial skepticism, until they meet their burden of evidence, and then are gradually accepted. So being initially rejected, like the H. pylori theory of gastric ulcers, is not enough.

Some pseudosciences, like phrenology (reading personality from the bumps on the skull), may get certain claims correct. It turns out that the brain is compartmentalized to some degree, as early phrenologists predicted. All the other claims of phrenology, however, are wrong, and once this was discovered by neurologists phrenology descended into pure pseudoscience. Now it persists as a tiny fringe belief.

In the end I cannot think of any examples of a belief that fully resided in the camp of pseudoscience whose core claims (not minor or incidental aspects of the pseudoscience) turned out to be correct and were later accepted by mainstream science.

Science is mostly about probability. It is not impossible that a belief that arises through pseudoscientific methods will turn out, by chance, to be true. It’s just highly unlikely. Most new hypotheses in science will turn out to be wrong. Those that have been shown to be wrong long enough to consider their proponents pseudoscientists, because only fatally flawed methods can still promote the claim, are really unlikely to later turn out to be true.

Very unlikely things do happen. So probably at some point in history there will be a dramatic example. One reason I am confident that no example exists now is because if there were such as example, pseudoscientists would be forever flogging it in the face of skeptics.

Further, while I cannot categorically say that any belief currently considered a full pseudoscience will never be confirmed and escape the pull of the black hole, I think the chance of that happening is vanishingly small.

Homeopathy, creationism, ESP, cold fusion, free energy, acupuncture, the growing Earth, astrology, vitalism, and dowsing are very likely to forever remain pseudosciences.

However, if one of these claims turned out to be true, its contemporary proponents would still be pseudoscientists. Remember, science vs pseudoscience is about method, not specific beliefs. Being right by chance despite using invalid methods still makes one a pseudoscientist – just a lucky pseudoscientist.