Saturday, October 31, 2009

Scientific Claims and Falsifiability

In my previous post I argued against an economist's criticisms of scientist's claims on truth. Arnold Kling does a much better job of making a similar criticism stick.

Arnold's argument boils down to this: Scientists sometimes claim that they will soon make particular discoveries or uncover particular knowledge, when in fact there is great doubt about whether they will.

These claims of impending success are common, and commonly wrong. More to the point (as Arnold suggests) these claims are unscientific, and therefore unbecoming to professed scientists, precisely because they are non-falsifiable. There is no theoretically possible method to disprove these claims (at the time they are made).

Science deals exclusively with claims that are (in principle) falsifiable. This is an extremely important part of why science works at all. By limiting scientific inquiry to falsifiable claims science is made testable and, ultimately, meaningful. If I believe that a scientific claim is false, I need only devise an experiment that will demonstrate a conflict or contradiction in order to prove that it is false.

Imagine what would happen if non-falsifiable claims were included under the domain of science. Under such a system scientists would concern themselves with claims that are mutually exclusive, but with no ability to distinguish between the truth or falseness of either. The discovery of knowledge would slow as time and effort were consumed in pointless and unending argument...

This is a concept that I'm sure all scientists are taught at some point early in their education. However, as important and fundamental as falsifiability is, many scientists seem to forget about it, or even become confused about what it means. Take, for example, Richard Dawkins' invocation of Russell's Teapot in support of militant Atheism. The bizarre thing here is that Dawkins uses Russell's Teapot as an example of a non-falsifiable claim, and therefore outside of scientific notice, while he simultaneously argues in favor of militant Atheism - which is a non-falsifiable claim as well. How can a scientist of such standing be so confused about one of science's founding principles?

Note: It  is important to recognize that Russell's Teapot may actually be a falsifiable claim, and therefore within  the purview of science. If you claim that there is a teapot in orbit, AND describe the orbit and the teapot in sufficient detail, then the claim is clearly falsifiable because the absence of the teapot in the specified orbit could, in principle, be observed. Militant Atheism, however is not a falsifiable claim because it is not possible, even in principle, to observe the absence of a god who can tweak the universe and human observation to achieve whatever end he/she/it desires. Militant Atheism must perforce fall outside of the notice of science.


  1. It seems that perhaps the most crucial part of science is that it deals with testable claims. Reproducing work affirms the conclusions. But, does this happen so much anymore? If it happens, we don't know about it. And it seems important that we should know.

    I find it interesting, too, that proposed benefits are one of the main tools to make many highly-specialized parts of science seem useful and relevant to us. How often have you heard about some grand project that's going to cure many diseases, but the reality is that it's just kept some geneticist in a job for a few years? The predicted outcome didn't materialize, not for the everyman. No cold fusion, no black holes in Europe...The truth is that the results of scientific study don't really impact us.

  2. How do you falsify some things? For example, I believe global warming is real, but how can you attempt to falsify it? Is there another planet we can have everyone on it not burn fossil fuels to see what happens?

    Robert R

  3. I agree that to prove something is true, you have to be able to prove that it isn't false, but just because you can't prove something isn't false doesn't mean it is false because you have failed to prove it isn't.

    Robert R

  4. Robert R,

    One of the requirements of falsifiability is that the claim must be specific. A lack of specificity is essentially why Russell's Teapot is non-falsifiable. As I pointed out, being specific about the teapot and the orbit can turn Russell's teapot into a falsifiable claim.

    A claim of global warming can be made specific with language to the effect that if atmospheric CO2 exceeds a particular concentration then global average temperature will increase above a given level. However, don't be fooled because even this kind of specific statement can easily be made general, and therefore non-falsifiable, by adding a disclaimer such as 'holding other variables constant'. Since all other variables cannot even theoretically be held constant, this one rider makes the entire claim non-falsifiable, and outside of the notice of science.

  5. Robert R,

    How do you prove that a claim is true? Isn't it always possible that your claim is actually false, but just appears true because it is similar to a true claim in some observable respect?

    Take an extreme case: you believe that an object exists because you can see it and touch it. But another possibility exists to explain your observation. You could be hallucinating.

    This is why science deals exclusively with falsifiable claims. You can't prove the truth of a claim, but maybe you can prove that it is false. By process of elimination you can winnow down to the claims that are most difficult to disprove because they are most similar to the truth.

  6. Ratio science, or the science of probability, helps to solve many problems. When a claim (Russell's Teapot) cannot be shown true or false, we assess what the more likely alternative would be and act as if it were so. Take your example: I sense an object is there but it is possible that I am hallucinating it. There is no absolute proof of my sanity, but probability overwhelming suggest that I am seeing a real object. This is why Russell's Teapot is such a powerful argument. It shows that a claim proved neither false nor true is not by definition equally likely to be both.

    But how about another example: Weighing the evidence, is it more probable that Richard Dawkins is confused about science, or that you are?

  7. Roy,

    Probability is enormously useful as you point out. However, I'd like to hear more of your thoughts on how you compute the probability of unobserved events/circumstances. Or how you compute the probability that your sensing apparatus is giving you false data (especially if you don't have alternative sensing apparatus to compare against).

    I have to agree with you that Dawkins wins over me in the appeal to authority department. But is appeal to authority the best counter to my arguments? And if it is, is Dawkins the best authority to cite on questions of philosophy of science?

  8. With respect to Dawkins, he has actually stated that he is agnostic is principal but with a little faith he is able to take things a step further to be a full atheist.

  9. Anonymous,

    That's good to hear. He should say it more often.

    After reflecting on Dawkins some more I've come to the conclusion that he's probably just being deliberately outrageous because it keeps him on the speaking circuit. Which is pretty depressing.

  10. What is the actual claim that Dawkins is making that is non-falsifiable? You say that militant atheism is a non-falsifiable claim, but it isn't a claim in itself.

  11. "militant atheism...isn't a claim in itself." Well, sure it is! Atheism, as opposed to Agnosticism, claims that there is no god. If Dawkins was a militant Agnostic I wouldn't have a bone to pick with him.

    1. I agree, the claim that there is no god is non-falsifiable. Atheism as the rejection of the belief in God is not the same.

    2. Seems like we're disagreeing over definitions. So I think the relevant question is, does Dawkins claim that there is no god? I'll look for some specific evidence, but I feel sure that he does.