Misunderstanding falsifiability as a power philosophy of Scientism
April 1, 2014 10 Comments
I think that trying to find one slogan that captures all of science and nothing else is a fool’s errand. However, it is an appealing errand given our propensity to want to classify and delimit the things we care about. It is also an errand that often takes a central role in the philosophy of science.
Just like with almost any modern thought, if we try hard enough then we can trace philosophy of science back to the Greeks and discuss the contrasting views of Plato and Aristotle. As fun as such historical excursions might be, it seems a little silly given that the term scientist was not coined until 1833 and even under different names our current conception of scientists would not stretch much further back than the natural philosophers of the 17th century. Even the early empiricism of these philosophers, although essential as a backdrop and a foundation shift in view, is more of an overall metaphysical outlook than a dedicate philosophy of science.
For me, philosophy of science was born toward the end of the 19th century as Mach’s instrumentalism and baptised in the late 1920s by the Vienna circle’s logical positivists. Combining the fledgling 20th century trend of focusing on language with Russell’s logicism and the fledgling transformation of Mach’s views into Bridgman’s operationalism, the logical positivist rallied behind a banner of verificationism as the be-all and end-all of knowledge. Their gravest error, and probably biggest appeal to scientists, was the division of statements into cognitively meaningful and emotionally meaningful and declaring the latter as ‘worse’ than the former. Only statements that could be empirically verified were cognitively meaningful and all other beliefs like say metaphysics were meaningless or at best only emotionally meaningful and thus not worthy of intellectual discussion. A perfect power philosophy for the scientist, and although justifiable at the time as a backlash against the overemphasis that idealists placed on metaphysics, it was quickly seen as oppressive.
Karl Popper’s famous response to the logical positivists was primarily motivated by two factors, one technical and one egalitarian. Unfortunately, both motivations are typically forgotten by scientists and laymen who tout Popper. First, falsification was introduced not because it better captured the reality of how scientists justified their beliefs, but to sidestep the technical problem of induction that was most famously raised by Hume. Even today, if you look at the language scientists use, even in the most empirical sciences it is seldom of the form “we built this complicated hypothesis and failed to refute it” (unless it was the null hypothesis that was not rejected, in which case the paper is seldom published) but usually more like “we showed support for this complicated hypothesis that we built”. For Popper, corroborating a theory should carry no weight, so most publications would be deemed irrational. In fact, the only time scientists typically invoke falsifiability is when they need to make a powerplay, to degrade something they don’t like as ‘unscientific’ and thus not worthy of discussion. This is in direct opposition to Popper’s second motivation.
Although Popper introduced falsification as a way to solve the demarcation problem, he did not create the demarcation problem to provide more power to scientists. Although for Popper there were non-scientific things he considered nonsense, simply being non-falsifiable (and thus for Popper, non-scientific) did not make something nonsense. Popper had respect for metaphysics. This was why for a logical positivist pointing out that verificationism is not verifiable is a strong critique (since it makes the basic tenet of their philosophy not cognitively meaningful), but pointing out to Popper that falsifiability is not falsifiable is just an obvious observation. It is also why Popper’s conception of the scientific is much more subtle and harder to grasp without careful reflection. In particular, most beginners are tripped up by falsification’s difficult relationship with logic.
Let’s start with where logic and falsification play nice: finite unions and intersections. If you have two falsifiable theories P and Q then P or Q is falsifiable because you can show the disjunction to be false by providing two observations with the first falsifying P and the second falsifying Q. For conjunctions, things are even easier: if P is a falsifiable theory and R is any statement (falsifiable or otherwise) then P and R is falsifiable by any observation that falsifies P. The ease of conjunction should also raise the first cautionary flag for you: since we can graft on any nonsense to a scientific theory and still remain scientific, we would need an extra tool for cutting away the excess guff. Unfortunately, for technical reasons, Popper cannot allow us Occam’s razor, but this discussion would be too much of a tangent.
The easiest real difficulty to notice is that for Popper, scientific statements are not closed under negation. The easiest way to see this, is that if they were then you could take a scientific statement P and its negation not P would also be falsifiable then by our previous reasoning the tautology P or not P would be falsifiable — an odd predicament indeed. The lack of closure under negation is also what makes falsification not equivalent to verification else if we wanted to verify something, we would just falsify its negation and vice-versa. This also means (by de Morgan) that scientific theories are not closed under implication.
If we move to first order logic then things become even more difficult. In section 15 of The Logic of Scientific Discovery, Popper notes that as isolated purely existential statement like “there exists an object of type T” is unfalsifiable. However, singular statements like “J is an object of type T“, Popper treats as falsifiable because without them he has no way to introduce falsifiers or observations more generally. However, this means that the logically valid introduction of an existential quantifier in going from a singular statement like “J is an object of type T” to “there exists an object of type T” makes a statement unfalsifiable. Scientific statements are not closed under introduction of existential quantifiers.
These properties of falsification are not critiques, but desirable features for Popper. They also imply — if it is not painfully obvious already — that not all non-falsifiable things are ‘bad’ or meaningless. For example, logic and more generally mathematics are both closed under all logical inferences. Thus, even though some mathematical statements are falsifiable and thus could be counted as scientific, mathematics and logic in its totality is not falsifiable and thus non-scientific for Popper. It is however, incredibly meaningful, useful, and fruitful. None of this would be a surprise for Popper, for some reason there is the unfounded myth that he set out to demarcate science from ‘bad’ pseudoscience, but that is simply not the case. As he writes early in The Logic of Scientific Discovery:
The problem of finding a criterion which would enable us to distinguish between the empirical sciences on the one hand, and mathematics and logic as well as ‘metaphysical’ systems on the the other, I call the problem of demarcation.
Nothing in the above suggests that not being an empirical science is ‘bad’. Similarly, being falsifiable does not make something ‘good’: “my feet are currently resting on a pink unicorn” is a falsifiable statement — a false one, in fact, but that doesn’t make it interesting. Similarly, let us look at Russell’s teapot:
If I were to suggest that between the Earth and Mars there is a china teapot revolving about the sun in an elliptical orbit, nobody would be able to disprove my assertion provided I were careful to add that the teapot is too small to be revealed even by our most powerful telescopes. But if I were to go on to say that, since my assertion cannot be disproved, it is intolerable presumption on the part of human reason to doubt it, I should rightly be thought to be talking nonsense.
Although the statement is carefully crafted to be not easily falsifiable, it is falsifiable-in-principle: we could build a spaceship and send it to where Russell says the teapot is and check. However, we won’t do that because although falsifiable, the statement is simply silly. In other words, if you want to dismiss this proposition (or, equivalently, the beliefs that Russell designed the argument to mock), you do not need to appeal to falsifiability, you can just rely on the usefulness of the statement or on Occam’s razor (although Popper would not approve of the latter).
Don’t equate falsifiable with ‘good’ or non-falsifiable with ‘bad’; the mistake of doing so is a misinterpretation by those unfamiliar with philosophy. Next time somebody dismisses or defends something as non-falsifiable or falsifiable, ask yourself: “So what? Is the statement useful? Interesting? Well articulated?” Especially if you deem yourself a skeptic, take the time to be skeptical of simple demarcations and the unnecessary power they bestow.