From astrophysicist Adam Becker at Aeon:
Falsifiability doesn’t work as a blanket restriction in science for the simple reason that there are no genuinely falsifiable scientific theories. I can come up with a theory that makes a prediction that looks falsifiable, but when the data tell me it’s wrong, I can conjure some fresh ideas to plug the hole and save the theory.
The history of science is full of examples of this ex post facto intellectual engineering. In 1781, William and Caroline Herschel discovered the planet Uranus. Physicists of the time promptly set about predicting its orbit using Sir Isaac Newton’s law of universal gravitation. But in the following decades, as astronomers followed Uranus’s motion in its slow 84-year orbit around the Sun, they noticed that something was wrong. Uranus didn’t quite move as it should. Puzzled, they refined their measurements, took more and more careful observations, but the anomaly didn’t go away. Newton’s physics simply didn’t predict the location of Uranus over time.
But astronomers of the day didn’t claim that the unexpected data falsified Newtonian gravity. Instead, they proposed another explanation for the strange motion of Uranus: something large and unseen was tugging on the planet. Calculations showed that it would have to be another planet, as large as Uranus and even farther from the Sun. In 1846, the French astrophysicist Urbain Le Verrier predicted the location of this hypothetical planet. Unable to get any French observatories interested in the hunt, he sent the details of his prediction to colleagues in Germany. That night, they pointed their telescopes where Le Verrier had told them to look, and within half an hour they spotted the planet Neptune. Newtonian physics, rather than being falsified, had been fabulously vindicated – it had successfully predicted the exact location of an entire unseen planet. More.
Kirk Durston responds,
I only read the first half of the article, but got discouraged at the simplistic approach the author took. Two examples:
“I can come up with a theory that makes a prediction that looks falsifiable, but when the data tell me it’s wrong, I can conjure some fresh ideas to plug the hole and save the theory.”
This is such a weak argument for abandoning falsification, that I’m not sure it even qualifies as an argument. The author appears not to have given much thought with regard to the quality, and category of a prediction. There are predictions that arise out of the theory, but are not central to it. If they are falsified, perhaps just a tweak to the theory is required as he mentions, but if they are verified, it does little to verify the core idea in the theory; the prediction is incidental. Then there are predictions that are central to the theory such that if they are falsified, the theory is dead in the water. For example, a central prediction of Darwinian theory is that there should be no boundaries to biological change. If that one is falsified, the central, core idea in the theory is dead in the water.
I am also disappointed in the simplistic example of Uranus and Neptune given in the article. Since Newton’s laws are based on masses, the gravitational constant, and distances, if a prediction is falsified, then either Newton’s laws have been falsified, OR there is another mass out there that is unaccounted for. This should be patently obvious; there is not just one possibility in this case. This is not an excuse or even an argument to abandon falsification. Rather, it is a lesson in experimental evaluation, especially of the data.
So after writing this, I checked to see who wrote it. I was not surprised to see the fellow is working in the shadowlands of astrophysics and QM, where it would be convenient indeed to abandon falsification. To his credit, however, he does state, “All that creative energy has to hook back onto reality at some point.”
Anyone who has had the misfortune of having a family relative heavy into all sorts of crazy conspiracy theories knows that any theory can muster up at least a tiny bit of evidence. It is falsification of the conspiracy that trumps whatever evidence they can muster. If we abandon falsification in science, then the line between conspiracy theories, science fiction and science gets pretty murky.
See also: The “difficult birth” of science’s assisted suicide, the multiverse (Adam Becker at Scientific American)
Biophysicist Kirk Durston: Canada’s governor general as a highly visible example of scientism