“Now, some physicists and philosophers think it is time to reconsider the notion of falsifiability. Could a theory that provides an elegant and accurate account of the world around us—even if its predictions can’t be tested by today’s experiments, or tomorrow’s—still “count” as science?
“We are in various ways hitting the limits of what will ever be testable.”
“As theory pulls further and further ahead of the capabilities of experiment, physicists are taking this question seriously. “We are in various ways hitting the limits of what will ever be testable, unless we have misunderstood some essential point about the nature of reality,” says theoretical cosmologist George Ellis. “We have now seen all the visible universe (i.e back to the visual horizon) and only gravitational waves remain to test further; and we are approaching the limits of what particle colliders it will ever be feasible to build, for economic and technical reasons.”
Must we throw it out because it fails the falsifiability test?
“It would be completely non-scientific to ignore that possibility just because it doesn’t conform with some preexisting philosophical prejudices,” says Sean Carroll, a physicist at Caltech, who called for the “retirement” of the falsifiability principle in a controversial essay for Edge last year. Falsifiability is “just a simple motto that non-philosophically-trained scientists have latched onto,” argues Carroll.
Carroll accepts evolution of the Darwinian formulation without question; he is not adverse to story-telling as science and that is what he is promoting for physics. But in terms of “empiricism”, he cannot claim with a straight face that such stories provide the objective knowledge which is the goal and entire purpose of empiricism. In fact, his denigration of falsification as “just a simple motto” indicates that either he doesn’t comprehend the concept of “objective” knowledge, or – more likely – that he is highly prone to developing ideological narrative to be passed off as “science”.
“He also bristles at the notion that this viewpoint can be summed up as “elegance will suffice,” as Ellis put it in a stinging Nature comment written with cosmologist Joe Silk.Of course, if that were actually the case, then only testable, data-generating theories would qualify and there would be no qualms about using falsification as a criterion for separating scientific ventures from non-scientific adventures. This is an unqualified use of the term "data" by Carroll, which misleads because the only data that exists is data regarding the effect - NOT any data regarding the cause, nor any data regarding the cause actually creating the effect.
“Elegance can help us invent new theories, but does not count as empirical evidence in their favor,” says Carroll. “The criteria we use for judging theories are how good they are at accounting for the data, not how pretty or seductive or intuitive they are.”
In his original article advocating abandoning falsification, Carroll claims that unobservable but real entities (such as the multiverse) can be determined by their effects. The example he gives is this:
“If the universe we see around us is the only one there is, the vacuum energy is a unique constant of nature, and we are faced with the problem of explaining it. If, on the other hand, we live in a multiverse, the vacuum energy could be completely different in different regions, and an explanation suggests itself immediately: in regions where the vacuum energy is much larger, conditions are inhospitable to the existence of life. There is therefore a selection effect, and we should predict a small value of the vacuum energy. Indeed, using this precise reasoning, Steven Weinberg did predict the value of the vacuum energy, long before the acceleration of the universe was discovered.”This is the classical Jump To Cause logic failure, and it is this sort of intellectual failure that empiricism was created as the Enlightenment path to objective knowledge in order to avoid. It can be called a "Cause of the Gaps" failure, or "Just So Story of the Gaps" failure, too. Most objective scientists would claim that just because an effect is observed does not mean that the very first cause one imagines is the correct answer. Conjuring causes is not the same as physically producing physical causes which might or might not be attached to a physical effect, and them testing them to observe the result. Carroll wants to remove that entire part of the definition of science; he's not alone, either (Note 1).
In this case there is an effect with no visible cause (if the conditions Carroll suggests are correct regarding vacuum energies); Carroll must make the presumption first that there actually is a cause. That is not a given except under Philosophical Materialism, which, of course, cannot prove it to be the case (a la Hume). But that presupposition is necessary for doing empirical science.
Now there may well be a physical cause, but unless that cause is found, tested to try to produce the effect, and found to indeed produce the effect, then it cannot be said to be objectively known to be the case that it is the cause. (Note 2)
Carroll is revealing his innermost desires by opening up the definition of science to include untestable claims. Those desires include the use of story-telling a la Darwin to continue to provide a patina of respectability for a science which does not deserve it.
For Carroll it’s not really about "explaining the data" as he claims. It is about maintaining science as the pursuit of elites, when in fact it has reached its limits of explanatory power through physical investigation. In order to move beyond those limits of observability it is necessary to enter the realm of the conjurings of fantasy, and so that is what is necessary to maintain science at its current cultural status.
Science, or at least evolutionary theory, moved into fantasy as soon as it started. Darwin began and ended with story-telling to fill in the knowledge gaps with fantasies – a practice that has metastasized into other sciences, and if Carroll has his way, now into the heady realm of physics. Despite his denials it is precisely about the "beauty" and "elegance" of equations in today's physics, not about the outcomes of testing. And as Hawking has pointed out, the equations use some fancy footwork in order to reach their conclusions, footwork such as cancelling infinities, for example. (what, exactly, is the precise numerical value of infinity divided by infinity?)
Carroll’s wrap up comments are revealing:
This paragraph contains several Ad Hominem Abusive denigrative attacks on Popper’s falsification demarcation, without a single logic argument being lodged against it. Popper’s falsification demarcation principle is “armchair theorizing”; a “fortune-cookie-sized motto”; “amateur philosophizing”; where “nature is the ultimate guide”, not principles of knowledge. He is engaging in Poisoning The Well against anyone who disagrees with his own principle that science does not need testability in order to be “science”; to argue against it, one would have to be an "armchair amateur defending a fortune-cookie". This is rhetorical theater and is despicable.
“Science is not merely armchair theorizing; it's about explaining the world we see, developing models that fit the data. But fitting models to data is a complex and multifaceted process, involving a give-and-take between theory and experiment, as well as the gradual development of theoretical understanding in its own right. In complicated situations, fortune-cookie-sized mottos like "theories should be falsifiable" are no substitute for careful thinking about how science works. Fortunately, science marches on, largely heedless of amateur philosophizing. If string theory and multiverse theories help us understand the world, they will grow in acceptance. If they prove ultimately too nebulous, or better theories come along, they will be discarded. The process might be messy, but nature is the ultimate guide.”
Further, it is not actually nature that is the ultimate guide, it is logic itself and the nature of what can be considered objective knowledge regarding nature. That is the underlying principle of empiricism. Unless hypotheses can be tested by replicable experimental processes by unbiased technicians who verify that the hypothetical causes do produce the observed effects, then the hypotheses do not – ever – deserve the status of objective knowledge. Data must include more than just the behavior of the effect; it must include the observation of the cause producing the effect, before the cause/effect can become objective theory of a natural phenomenon.
If Carroll does not know that, then he does not deserve to be considered an objective scientist, much less a credible philosopher of science.
Note 1. For more sources see the end of her article.
Note 2. In fairness, it cannot be said that any cause/effect relationship is immutable, incorrigible "fact"; this is because hypothesis testing, no matter how often it is done with positive results, cannot avoid the possibility that some increase in knowledge or technology will produce better tests which would, in fact, fail and thus falsify the hypothesis. Science does not ever produce Truth; it can produce only contingent factoids which are presumed to be reasonable - if mutable - knowledge. However, that knowledge is objective only if the testing can be done and is done by other unbiased experimenters as well.
HT: Steven Satak