On falsificationism

by Neil Rickert

Jerry Coyne asks, “Is falsifiability a good criterion for a scientific theory?”  My short answer is “No”, but I’ll try to flesh that out.  Coyne writes:

The “theory” of evolution, for example, could be disproven if we regularly found well-dated fossils out of the proper order (like mammals in the Devonian, for instance), if species didn’t have genetic variation to respond to selection, or if we often found “adaptations” in member of one species that were useful only for another species (e.g., a special nipple on a female mole that was only used for suckling mice).

I’ll disagree with that.  If the theory of evolution (let’s assume neo-Darwinian theory) were falsifiable, then the discovery of horizontal gene transfer should have already shown it false.  If, however, the theory is a framework that functions as a guide to research, then it is neither true nor false.  It will be retained as long as it continues to be useful as a framework.  Minor discrepancies, such as horizontal gene transfer, can easily be absorbed into that framework.

My view is that a scientific theory exists as such a framework, and is measured pragmatically (by its usefulness), rather than on a true/false basis.

I’m told that falsification is naive as a criterion for good science, and that scientists no longer accept or use that as a criterion.

I’m not convinced that scientists ever used it, except to make rhetorical points (such as in arguments with creationists).  I would reword that as “many philosophers no longer say that scientists use falsifiability as a criterion.”

Is there any scientific fact or theory that is widely accepted despite the fact that it is not in principle capable of being falsified?

It’s difficult to say.  But take the ideal gas laws of physics.  As applied to an ideal gas, they are unfalsifiable, because ideal gases exist only in our minds.  As applied to real gases, those laws are well known to be false, but are still useful as a close approximation.  If they are known to be false, but still used, does that make them unfalsifiable?

For facts, consider the fact that, during the Newtonian era, the mean solar day was 24 hours long.  This was unfalsifiable, because it was the definition of the units of time.  It was very much used as a scientific standard.  If we look at any scientific standard today, that standard, expressed as a proposition, will be unfalsifiable because it is true by definition.  It is my impression that Popper’s criterion was specifically aimed at propositions that are true by definition.  But, if applied consistently, it should have ruled out all scientific standards.  Fortunately, nobody tried to use it that way.

It is my impression, for instance, that string theory in physics isn’t widely accepted as true simply because we haven’t found a way to test it—to test that its predictions are verified or not.

That’s my understanding.  I never did consider it a scientific theory.  I looked at it as a speculative hypothesis.  The problem, as I understand it, is that they were never able to find a way of connecting the terms of string theory to real empirical data.  So it fails the usefulness test.  And that requirement, that the terms of a theory should be able to be connected to empirical data, and that the theory prove useful after making that connection — that is what should have been the demarcation criterion.

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One Comment to “On falsificationism”

  1. I agree with Popper in that falsifiability is a good criterion for a scientific theory. However, just because a scientific theory is disproven doesn’t mean that it fails to be useful. In the case of evolution, whenever something specific arises that appears to create a nick in the theory, it is slightly modified and/or a new theory is proposed. If there are useful parts of the previous theory, they can still be used in developing new theories, as long as those parts specifically haven’t been falsified.

    In the case of evolution, in my opinion, generally speaking it is nothing more than “change over time”. No matter what happens, this is something that exists in our gene pool (we’ve monitored these changes even within a bacterial generation time-scale) and natural selection will inevitably modify that gene pool by environmental pressures (some genes will be more likely to survive depending on the environment). If any specific variations of the evolutionary theory are proven false, it does not mean that evolution as a whole is false. It just means that the theory needs to be modified or specify it’s known limitations (be written correctly) allowing the theory to potentially remain. I understand that the theory of evolution was mentioned as an example to demonstrate falsifiability, but I figured I’d give my opinion that in general it will never be proven false, even though there are certain hypothetical conditions that could prove it to be false — thus it is falsifiable.

    Regarding String Theory, I agree with you in that I never considered it a scientific theory either. I don’t really think it is falsifiable as the theory requires several extra dimensions which are not only impossible to conceptualize, but could never be observed (since they are outside our 3-spatial dimensions) — hence unfalsifiable.

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