Hi, this is Logan Chipkin, and you’re listening to the Fallible Animal podcast. Today we’re going to begin our deep dive into the philosophy called Critical Rationalism.
We’ll be using technical jargon liberally, but I’ll define each term as we go.
To begin, I should say that critical rationalism is an epistemological theory. Just as biology is the study of living things, and chemistry is the study of how forms of matter interact with each other, epistemology is the study of knowledge — what it is, how it grows, how it can be discovered, and so forth. So epistemology is essentially just a mouthful for ‘the study of the nature of knowledge’.
Much like quantum mechancis and general relativity are some of our deepest theories in physics (there is a deeper one, which we’ll explore in a later episode), critical rationalism is our deepest and best theory in epistemology. Now, I could described critical rationalism a philosophy of science, or a philosophy of knowledge, or a philosophy of how either of those progresses, but at heart, it’s actually a philosophy of problem-solving. For our purposes, though, for the rest of this episode, we’ll focus on how critical rationalism applies to problem-solving in science and other intellectual pursuits. Since all intellectual pursuits are fundamentally about pursuing knowledge, critical rationalism is rightly called a theory of knowledge, or a theory of epistemology.
Let’s go back several decades, so that we understand the intellectual climate in which critical rationalism arose. At the dawn of the twentieth century, physicists had considered the science to be pretty much wrapped up, with only a few lingering problems left to solve. Famously, in 1894 the experimentalist Albert Michelson said something like “All of the important fundamental laws and facts of physical science have all been discovered, and the possibility of their ever being supplanted by new discoveries is exceedingly remote”. For physics, the end of history, it seemed, was approaching.
Yet by the 1930s, the community of physicists was reeling from not one but two revolutions that turned its worldview upside down — those of general relativity and quantum mechanics. Einstein’s first paper on general relativity was published in 1915, while the phrase ‘quantum mechanics’ was first used by Max Born, one of the founders of the theory, in a 1924 paper. We’ll explore the origins of both of these colossal theories in a future episode, but for now, just try to imagine what these physicists might’ve been thinking — in little more than a generation, they went from believing that they were nearing the summit of the mountain, only to discover that the real peak was perhaps beyond sight entirely, two times over!
In the meantime, Sigmund Freud’s theories of psychoanalysis were growing more and more popular in the Western World. There’s a lot here — some of you might know about his model of the human psyche as being composed of the Id, the ego, and the superego, the details of which are elaborated upon in his 1920 essay, Beyond the Pleasure Principle. or you might just know about his theories of dreams from his 1899 book, The Interpretation of Dreams, or even just his theories of psychosexual development. The details of Freud’s theories don’t really concern us here, only that they grew to be popular in the early 20th century.
And finally, the political doctrine of Marxism was on the rise in the first half of the 20th century. The details of this certainly don’t concern us here, as we’d end up in an entirely different rabbit hole.
But the point is that advocates of both Marxism and Freudianism claimed that their theories were scientific, as much as those who accepted the new physical theories of general relativity and quantum mechanics did.
Add to this the debate over how to interpret the new, radically counterintuitive theory of quantum mechanics, and people began turning to philosophy for answers…or questions.
What, exactly, is a scientific theory in the first place? Could it be as simple as the creating of a set of ideas, coherent or not, and simply declaring it as ‘scientific’? And if ideas can be overturned, as our previous worldview was with the advent of general relativity and quantum mechanics, how are we justified in claiming that science progresses at all?
By the way, as a quick digression — the fact that quantum mechanics caused scientists to reconsider how the process of science works in general is a nice example of a revolution in one field — in this case, physics — forcing us to think more critically about another field, in this case, epistemology. When deep enough theories in one field are overturned, there are often ripple effects into other areas of thought. We’ll see other instances of this ripple effect in future episodes.
In comes the Viennese philosopher Karl Popper, who answered all of these questions with his epistemological theory, his theory of knowledge, called critical rationalism. His first book expounding on the theory, called The Logic of Scientific Discovery, was published in 1934 in German. Fearing the rise of the Nazis, he actually wrote it so that he could acquire an academic position in a country that he thought would be safe for those of Jewish descent. The English translation was published 25 years later in 1959, by which time he was a professor at the University of London. He continued to refine his theory, and published many more works on the subject, and on many other topics, for that matter.
It’s difficult to know where to begin when explaining the theory of critical rationalism, which I suppose is fitting, since the whole point of it is that there are no foundations upon which we build some great, infallible edifice of knowledge. So we may as well start in the middle and see where that takes us.
When the scientist ‘does science’, as it were, she’s fundamentally aiming to understand, to explain Reality. So our ancestors noticed a bright orange shape in the sky above them, and they conjured up what we now regard as myths to explain them. But it’s only with hindsight that we dismiss their explanations as myths — the hindsight of having a much better explanation at hand.
So the problem that the scientist wants to solve could be an apparent regularity, like the daily motions of the Sun in the sky. It could also be an irregularity, like storms that occur with no predictable schedule at all.
Either way, the scientist’s aim is to understand, to explain the phenomena of the empirical world — regular, irregular, or something entirely novel, never before encountered.
But there is no cookbook with the explanations we seek, nor are the answers written among the stars. The scientist must engage in creative thought — here, he may undergo trying hours of failure, of searching down abstract tunnels that turn out to lead to nowhere. But eventually, he may come up with what he considers to be a solution to the problem at hand, an explanation for that which he could not previously explain.
The scientist then subjects his new theory to criticism — and even this step is a creative one, for attacks on his theory can come from an infinite number of angles. He could check for internal consistency. After all, if a theory leads to a contradiction with itself, it probably requires either modification or a return to the drawing board entirely afresh.
Another mode of criticism that isn’t always made explicit is to check whether some new theory is consistent with other theories that we hold to be true. For example, there’s a famous unsolved problem in biology known as the latitudinal diversity gradient problem. Basically the number of species increases as proximity to the equator increases, and no one knows why, though many hypotheses have been proposed. Imagine someone posits a new hypothesis to explain this phenomenon, which asserts that the diversity gradient is a consequence of the fact that because temperature increases as one moves from the poles to the equator, the greater amount of environmental heat at the equator provides more energy for the spontaneous generation of novel species. This conjectured hypothesis contradicts Darwin’s theory of natural selection, which implies that species cannot spontaneously emerge, but instead require adequate rounds of mutation and selection. Therefore, one criticism of this new hypothesis would be that it contradicts another theory we’ve already accepted, for wholly independent reasons. To be sure, this is not necessarily a death blow to the new hypothesis — logically speaking, it may well be that Darwinism is false, and that this new heat-diversity hypothesis is correct. But Darwinism had already survived all attempts to criticize it, while this new hypothesis has not done anything of the sort. So on the basis of its conflict with Darwinism alone, we have reason to disregard it.
On the other hand, there is another mode of criticism, one with which most people are familiar -that of experimental testing. Any empirical theory must be such that there is some observation you could make in principle that would contradict the theory. Another way of saying this is that a theory must make *predictions* of the form ‘if this theory is true, then such-and-such event will occur under such-and-such circumstances.’ We have arrived at Popper’s famous ‘criterion of demarcation’ — that is, a theory is scientific if it is *falsifaible* — capable, in principle, of being refuted by the outcome of some specified experiment. So while Einstein’s theory of GR was apparently elegant, and perhaps sensible enough to accept, his theory rocketed to fame only after the theory’s prediction for the bending of light around massive objects was corroborated by images of an eclipse in 1919, captured by the astronomer Sir Arthur Eddington.
I should say that experimental testing — and the gathering of evidence from the environment — is most helpful as a mode of criticism when we have two or more theories that make different predictions for the same physical event, and when all such rival candidates have survived other modes of criticism. So if we had a theory that had a prediction differing from, say, Newton’s theory of motion, we still wouldn’t bother putting them both to the test if the new theory was internally inconsistent, lead to absurdities, that kind of thing.
But general relativity seemed like a good theory — from a few basic postulates that seemed to hold true, an entire explanatory model of gravity, space, time, energy, and mass, was created. Yet for many classes of physical events, the theory made predictions that contradicted those made by another theory that was widely accepted at the time — Newtonian physics, which had reigned supreme since 1687. For example, Newton’s theory, which was all about how objects move in responses to forces acting on them, predicted that light would not bend around massive objects like stars. While Newton’s framework posited that space and time were essentially static, effectively just the background in which interesting things happened, Einstein’s general relativity held that space and time were far more dynamic, themselves warping and bending in the presence of massive and energetic objects. And this dynamical background, in turn, affected the motion of other objects. To quote the great physicist John Wheeler, “spacetime tells matter how to move; matter tells spacetime how to curve.”
We don’t have to get too lost in the weeds regarding the content of GR and Newtonian physics. The point is that they made different predictions for the same physical processes, and so could not both simultaneously be true. For example, Newton’s theory predicted that light would not bend around a massive stellar object, while general relativity predicted that it would, and by precisely how much it would bend. That’s why Arthur Eddington’s images of that fateful 1919 eclipse are so powerful — they refuted, or falsified, Newton’s theory in favor of Einstein’s general relativity. The evidence, those points of light from faraway stars, were in fact displaced due to our own Sun’s gravitational field, exactly as general relativity predicted, and in contrast with what Newton’s theory predicted.
So scientific theories should be falsifiable, testable, refutable, whichever word you want to use. And Popper himself noted that Freud’s theories didn’t seem to fit this bill. No matter what someone’s psychological profile was, a Freudian was always able to explain it in Freudian terms. Now that might seem like a virtue, but it’s in fact a vice. For a theory that explains anything actually explains nothing. Marxism, too, seemed to be able to account for any socioeconomic occurrence. Again, while this may make the theory appear profound, quite the opposite is true. So both Freudianism and Marxism, according to Popper’s criterion of demarcation, are deemed unscientific. Neither makes any concrete predictions that, if shown to be false, would be problematic for the theory.
Let’s take stock of what we’ve learned. According to critical rationalism, the theory of knowledge that we’re investigating, we seek to solve problems in our worldview, to better understand and explain the world around us. We then, through an often long and arduous creative process, develop explanations — conjectured theories to account for some aspect of Nature. Following the creation of a theory, we then *criticize* it with all of the weapons in our arsenal. This includes, but is not limited to, gathering data, evidence, and experimental testing. Such testing is most useful when we have two or more rival, testable theories for the same class of phenomena. The outcome of some particular experiment, called the crucial experiment, by the way, will then refute all but one of the theories. The theory that survives the test is said to have been corroborated, the others falsified.
Notice that there can be no certainty in this framework. We are forever guessing as to the truth of the matter with our conjectures. Any of our theories, at any time, could be rendered problematic by some new piece of evidence, or more generally, some new mode of criticism that had not yet even been conceived of. So our theories are forever tentative, forever subject to modification, supersession, or refutation.
And all empirical theories must be falsifiable — that is, they make predictions that could in principle be contradicted by the outcome of some experiment, or some piece of evidence.
But if nothing is certain, and we could drop even our best theories at any moment, does science ever really progress? Or are we just running in circles? Indeed, science does progress by way of error-correction, which we did not discuss explicitly today. But now that we understand the aim of science — that is, to explain and understand Reality, and we know the process by science operates — namely, conjecture and criticism — we’re ready to talk about error correction as it pertains to critical rationalism. We’ll pick up on this very important idea next time, on the Fallible Animals podcast. After that, we’ll discuss the rival epistemological theories to critical rationalism, such as inductivism, and why we are confident that critical rationalism is the correct theory of knowledge (or at least, the best one yet conceived).
Thank you for listening. I’m your host, Logan Chipkin. You can follow me on twitter @ChipkinLogan, and you can read some of my articles on www.loganchipkin.com. If you liked this episode, please consider sharing. Let’s get these ideas out there. Have a great day.