Massimo Pigliucci on the boundary between science and pseudoscience

In this video, Massimo Pigliucci, the philosopher and biologist who runs the Scientia Salon site, discusses the demarcation problem, the dividing line between what is and is not science.  The distinction is easy for things like astrology and astronomy, but gets more difficult for many other areas.

I’d forgotten about Massimo’s latest book on pseudoscience.  It’s now queued up in my Kindle account.

I found this talk interesting and enlightening.  But one thing I found puzzling was Massimo’s apparent dismissal of falsifiability as a useful criteria for distinguishing science from non-science.  I may change my mind once I’ve read the book, but for now, I think I disagree, for a couple of reasons.

The first reason involves the distinction between using falsifiability in scientific work versus using it as a criteria for what is science.  Massimo discusses two historical scenarios I’ve discussed myself in the past.

The first scenario was when the orbit of Uranus didn’t match the predictions of Newtonian mechanics.  Rather than assume that Newtonian mechanics had been falsified, astronomers predicted the existence of a new planet which turned out to exist: Neptune.

But in the second scenario, faced with  anomalies in the orbit of Mercury, astronomers predicted the existence of a planet closer to the sun, which they prematurely named Vulcan, but which turned out not to exist.  Ultimately, the problems with the orbit of Mercury were in fact a falsification of Newtonian mechanics.  (Mercury’s orbit was eventually explained by Einstein’s general theory of relativity.)

The point Massimo and other philosophers make is that there is no way to know at the beginning of these scenarios whether the contradictory observations are from the scientific theory being wrong or the existence of unknown factors, like the existence of a new planet.  And that is true.  Discovering that a scientific theory has been falsified takes expert judgment, and often a lot of time.

But judging whether or not a theory has been falsified is different than judging whether or not it is a scientific theory.  And by that standard, falsifiability makes it very clear that Newtonian mechanics was science, and falsifiable.  If it hadn’t been, there might still be schools of physics dedicated to Newtonian mechanics today.

My second reason for disagreeing with Massimo goes somewhat to my general attitude toward philosophical guidelines, which is that the perfect is the enemy of the good.  I fully admit that falsifiability is not a perfect criteria.  For example, slavish adherence to it might prematurely exclude speculative but legitimate concepts that may eventually lead to falsifiable theories.  But it works well in the vast majority of cases, and is often a good guiding principle for separating a scientific idea from a philosophical one.

I will agree though that falsifiability is not as good for the specific demarcation between science and pseudoscience.  Many purveyors of pseudoscience make falsifiable claims, but they often overlook or ignore the fact that their claims have already been falsified.  I think the real divide between these two areas is whether or not the practitioners are honestly pursuing knowable truths, and whether or not they are doing it competently.  Shysters and con artists are dishonest, and crackpots are incompetent, and often the purveyors of pseudoscience are both.


14 thoughts on “Massimo Pigliucci on the boundary between science and pseudoscience

  1. It all comes down to this – lets say Neptune was not found and Newtonian physics was proved wrong at that time itself. So its now a false theory. But lets say there exist some set of people who honestly believe that Neptune exists. Now how do we determine who is right? Nietzsche’s quote comes to mind: Those who were seen dancing were thought be insane by those who could not hear the music.

    Now if the whole world believed that Neptune exists, then Newtonian physics would be considered right by those people. So it all comes down to – which belief do we give value to. It all comes down to belief.


    1. Hmmm. Well, if we continued to have strong logical and mathematical reasons for thinking Neptune was there, but it stubbornly refused to show itself in our telescopes, we might take to calling it Dark Neptune. On the other hand, if we found a workable alternative to Newtonian mechanics that explained observations better, including Neptune’s absence, then science would conclude that Neptune wasn’t there and move on, although that decision would always be subject to revision if new evidence ever arose.

      Of course, people might continue believing in Neptune if they had some emotional commitment to it, but they could no longer honestly claim that their belief was scientific.


      1. Let me give you another example. There was a woman who couldn’t see objects in motion. So if there was a truck moving by, she only saw fixed images of the truck but not the complete motion. She got that way because of an accident and she had some brain damage. Now if the whole world had that condition, wouldn’t we have a different concept of “Time” and Laws of Motion? If we had a different concept of Time, what would our Laws of Physics look like? So I am trying to say that what is “logical” or “mathematical” depends on what the structure of one’s brain. Even our belief comes down to the structure of our brains.


        1. Certainly, our ability to understand reality is intimately tied to how our brain and senses work. And logic and mathematics may be theories about how reality works borne of innate evolutionary knowledge and primal experience. It pays to be aware of these limitations and biases. But it’s possible to let ourselves become too preoccupied by them to the point that it becomes a hindrance to the pursuit of knowledge.

          There may well be aspects of reality that we are blind to, but if they have any effects on the aspects of reality that we can experience, any relevance to us at all, then we can learn about them indirectly. No one has ever seen a subatomic particle, or gravity, but we know a great deal about them from their effects on things we can experience.


  2. I think I agree with you on this issue (I haven’t read his book either and I’m in no way sure of anything when it comes to science!). I think the difficulty of determining a theory to be false is a separate issue from whether a theory CAN be falsified. We can determine the latter a priori, at least in outline…even if there are factors we couldn’t possibly know about, we can still say “such and such would disprove the theory, excepting extraordinary factors.” And then go test it. And test it, and wait, and talk, and…someone three or ten generations later can tell us what happened.

    I think it’s important to have that criterion of falsifiability for a scientific theory. You’re right, though, pseudosciences often have falsifiable theories, so we can’t make falsifiability a defining factor.
    But an unfalsifiable theory just sounds…really really unscientific.

    But don’t believe a word I say. My criterion for whether something is real is whether or not it has a cool name. Therefore, Vulcan is out there. It’s just so bright we can’t see it, but one day, with special Vulcanized telescopes, we will. And if we still can’t see it, it’s because our telescopes aren’t Vulcanized enough.


    1. Perhaps we’re just not ready to see Vulcan yet. 🙂

      I do think Vulcan exists, in the sense that sooner or later we’re going to name something “Vulcan,” although I’m not sure whether we’ll be thinking of Hephaestus or Mr. Spock when we do it.


        1. I’m sure it does depend on the dog, and the climate, and how young you start them. My old dogs scratched and chewed at anything we tried to put on them, but we never tried it with them when they were puppies, and living in the deep south, it was usually unnecessary.


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