The provocative title of the Scientific American Article below, by physicist Mano Singham, is, I think, deeply misleading. The idea that science progresses by eliminating incorrect explanations, which is what falsification is all about, seems to me not only a good strategy, but one that's historically worked very well. To say it's a myth is not even wrong.
But let's hear why Singham says that falsification can't work. Click on the screenshot to read his piece.
Before we get to Singham's argument, we notice that we can immediately think of scientific theories that have been definitively falsified. One is that the Earth is flat. That has been falsified by any number of observations, and now nobody except loons accepts a flat planet. Alternatively, the Genesis story of creation, once a "scientific" explanation for the origin of life and, especially, humans, has also been falsified, also by any number of observations. It was replaced by a better theory: evolution, and you can see the process of falsification by reading The Origin, as everyone should. Darwin not only adduces evidence for evolution from biogeography, embryology, the fossil record, vestigial organs, and so on, but at the same time notes how these observations do not comport with creationism, the main competing hypothesis at the time. The falsification of creationism is why Darwin was so worried that religious people would reject his theory.
For if observations comport with both of two competing theories, this gives us no way to determine which is the better one. Darwin shows in his biogeography chapters, for example, how the distribution of animals and plants on Earth jibes with an evolutionary theory combined with the idea that organisms disperse, but cannot be explained by creationism. (Why would the creator not put native mammals, freshwater fish, and amphibians on oceanic islands?) The book's falsification of creationism combined with its support of evolution meant that, within about a decade after 1859, nearly all educated people accepted that Biblical creationism had been falsified.
Why, then, given the above, does Singham think that falsification—the classic strategy of scientific advance limned by Karl Popper—is a "myth"? He gives two reasons (he's referring to Haldane's "Precambrian rabbit" as a proposed falsification of evolution):
1.) Falsification is complicated. Singham says this:
But the field known as science studies (comprising the history, philosophy and sociology of science) has shown that falsification cannot work even in principle. This is because an experimental result is not a simple fact obtained directly from nature. Identifying and dating Haldane's bone involves using many other theories from diverse fields, including physics, chemistry and geology. Similarly, a theoretical prediction is never the product of a single theory but also requires using many other theories. When a “theoretical” prediction disagrees with “experimental” data, what this tells us is that that there is a disagreement between two sets of theories, so we cannot say that any particular theory is falsified.
Fortunately, falsification—or any other philosophy of science—is not necessary for the actual practice of science.
I don't quite get this. If many lines of evidence (or many scientific fields) converge on a conclusion that contradicts an existing theory (evolution in this case), that doesn't mean that falsification doesn't work, just that sometimes it's not so easy. In fact, in the case of a Precambrian rabbit, scientists wouldn't take a single observation as overturning a theory supported by so much evidence in favor of a theory—creationism—supported by none. Scientists would work hard to make sure that date wasn't an anomaly, whether the rabbit somehow got itself insinuated in Precambrian sediments, and so on. Further, we'd like more than one fossil, for a theory as well established as evolution would require a multiplicity of "wrongly placed" fossils to make us question it. This doesn't mean that falsification is a myth, just that when you use it against a theory that's very well supported, you have to use it many times.
And sometimes an experimental result is indeed a "simple fact" obtained directly from nature. The idea of a pancake Earth is simply refuted by sending a satellite around the planet and not finding an edge. This case also shows that Singham's claim that "a theoretical prediction is never the product of any single theory" is wrong as well. A flat earth (some get the idea from the Bible) is a single theory, not depending on "many other theories."
Another example is Meselson and Stahl's lovely and definitive refutation of two models of DNA replication ("conservative" and "dispersive"), confirming the "semiconservative" model with a simple and beautiful experiment involving centrifugation of radioactively labeled DNA as it replicated. Just because radiochemistry, centrifugation, and biochemistry were involved doesn't make the experiment any less of a falsification. And there were only two other credible theories being tested, not "many other theories." Since then, the entire science of molecular genetics has depended on their 1958 result, and it's held up. If this isn't an instance of verification of a true theory by falsifying alternatives, I don't know what is.
Here's Singham's second reason why falsification is a "myth":
2.) Pseudoscientists, cranks, and enthusiasts claim that they have data falsifying "consensus" theories, and this tactic makes falsification a dubious strategy. Again, I don't quite get this, but here's what Singham says:
A knowledge of the historic and philosophical background gives that kind of independence from prejudices of his [Einstein's] generation from which most scientists are suffering. . .
. . . this knowledge equips people to better argue against antiscience forces that use the same strategy over and over again, whether it is about the dangers of tobacco, climate change, vaccinations or evolution. Their goal is to exploit the slivers of doubt and discrepant results that always exist in science in order to challenge the consensus views of scientific experts. They fund and report their own results that go counter to the scientific consensus in this or that narrow area and then argue that they have falsified the consensus. In their book Merchants of Doubt, historians Naomi Oreskes and Erik M. Conway say that for these groups “[t]he goal was to fight science with science—or at least with the gaps and uncertainties in existing science, and with scientific research that could be used to deflect attention from the main event.”
But this no more refutes the value of falsification than it refutes the value of science itself. For the same zealots and pseudoscientists who use the idea of falsification also pretend to use the methods of science. I don't think I need say more about this.
Finally, near the end of his article Singham comes close to admitting that yes, falsification works:
Science studies provide supporters of science with better arguments to combat these critics, by showing that the strength of scientific conclusions arises because credible experts use comprehensive bodies of evidence to arrive at consensus judgments about whether a theory should be retained or rejected in favor of a new one. These consensus judgments are what have enabled the astounding levels of success that have revolutionized our lives for the better.
But how do you go about rejecting a consensus theory, like creationism, in favor of a new one? You have to find evidence that comports with the new one and not with the consensus. And that is falsification.
Now it's possible that there is no competing theory, and you're just looking for evidence that comports with the only theory you have. But even that is, in some sense, falsification: falsification of the idea that your theory is wrong, even if you don't have an alternative. If you think benzene has six carbon atoms, then your alternative theory is that benzene doesn't have six carbon atoms, but more or fewer, and you look for evidence for falsifying one or the other of these theories.
I think Singham intended to support the value of science studies—the history and philosophy of science—at a time when some people denigrate them. Richard Feynman famously said “philosophy of science is as useful to scientists as ornithology is to birds”. I don't agree with him on either count—ornithology is useful to birds, by helping conserve them, and philosophy of science can help us think more clearly about our problems and methods. But sometimes science studies can be impediments by confusing people about the nature of science or making insupportable or useless statements, like there's no external reality independent of our senses. And one of these impediments is the claim that falsification is a myth.