 Hi, welcome back to history and philosophy of science and medicine. I'm Matt Brown. Today we're talking about the philosophy of Karl Popper Now Karl Popper was a philosopher who lived from 1902 to 1994 He began his life and his career in Vienna And just like the logical positivists and like the logical positivists he fled Europe during the rise of the Nazis prior to World War two move from Austria to New Zealand and then later settled in England at the London School of Economics Popper was a complicated thinker one with a significant following among philosophers and also scientists And it's interesting to think about his legacy in the context as Peter Godfrey Smith says of the fact that he is by far one of the most popular and well-known philosophers amongst scientists Now early in his intellectual development Popper had significant Interactions with the thought and in some cases the personages of the following four Scientific thinkers Sigmund Freud and Alfred Adler the psychoanalysts Karl Marx the historian sociologist and Economist and the physicist Albert Einstein Popper in his youth was Briefly a Marxist definitely interested in Marx's radical thought However, he became kind of disillusioned with Marx at a certain point He was similarly interested in psychoanalytic theory and actually worked for a time as a social worker under the tutelage of Alfred Adler, but he became disillusioned with their ideas as well he also attended a lecture by Albert Einstein that was very influential on him and through the course of these interactions Came to to sort of frame a lot of his intellectual development in terms of what he came to see as negative features of the thought of Freud Adler and Marx and positive features of the work of Einstein namely that while Psychoanalysis and Marxism seemed very impressive and their ability to explain and accommodate information About a wide variety of things It seemed very difficult to find any kind of situation real or hypothetical that they couldn't explain whereas Einstein's physical theories made bold predictions that could have turned out to be false and this turned out to be a very Very influential idea for Popper Popper had many works that we think of as significant Books wrote a number of books in the field probably the most important works of philosophy of science include The work he's most well known for the logic der Froschung or the logic of scientific discovery Published in German in 1935 and in English in 1959 as well as books that Followed up on and developed his thought in further directions including conjectures and refutations in 1963 and Objective knowledge in 1972. Although these are by no means his only important works. He also published two works of social and political philosophy the open society and its enemies and the poverty of historicism And both of those are characterized. I think broadly As we can characterize them broadly as anti-totalitarian also anti utopian and anti-Marxist and They speak not only I think to Social and political philosophy, but also include some significant thoughts about the philosophy of the social sciences as well, but we'll focus for our purposes primarily on his philosophy of science and these other kinds of works One of popper's significant Contributions to the philosophy of science is his articulation of what we now call thanks to popper the demarcation problem The demarcation problem is the is basically the question. How do we distinguish? science from non-science and particularly those those Activities that are kind of on the border. They look like science But we maybe don't want to consider them to be scientific per se At first popper characterized this question as a question of different types of theories. What would distinguish a It's properly scientific theory from a non-science or pseudo-scientific theory and later Even in even in early parts of his thought I think he kind of shifts from thinking of this in terms of theories And instead thinks of it in terms of the practices or attitudes of the scientists in question Although he's never too clear on that. I think it's worth emphasizing how different this This focus is from the focus of the logical empiricists The logical empiricists with their verification is And they're they're they're interest in the concept of what is cognitively meaningful Are doing something similar to the demarcation problem, but not the same the logical positivists or logical empiricists in our Yes, focusing on science using lessons from science But they're they're sort of waging battles so to speak in a broader philosophical context they're interested in knowledge and truth and meaning in a in a broad philosophical sense and Popper is not interest so interested in those questions. He doesn't think that just because something is non-scientific It's meaningless or false or Not a contribution to our knowledge, but he thinks there is something distinctive and important about science That is not captured by certain things and he thinks it's important that we not be You might say fooled into thinking a certain kind of activity or theory is scientific when it isn't Okay, and Popper's answer to the demarcation problem is the doctrine that he calls falsificationism, right? And this is probably what Popper is most well known for his view that in order to be scientific a theory has to be refutable by some specific observations or some specific evidence So what characterizes science is that it takes risks it makes predictions that could turn out to be false and It makes predictions about things that are novel that we don't already have the answers to And what characterizes pseudoscience according to Popper? Is that although it it makes a kind of prediction or it makes empirical claims? Those empirical claims are not risky, right? because because even if they turn out to be Incorrect the theory can it kind of explain that away Another way to put it is that the theory can accommodate any observation whatsoever That's a characteristic of pseudoscience according to Popper Now there are some problems here right away one it's not clear logically speaking that you can pin down a false prediction to to the theory, right? instead of something wrong with the way you've described your observation or Some other auxiliary assumption that you've made we talked about some of those issues last time So one thing that Popper is forced to acknowledge is that in a sense whether a theory is falsifiable depends on decisions made by the scientists about what to count as evidence and Where to when to say that the The problem is the theory in question and not say your your equipment your your observation equipment nevertheless Something for Popper is is considered pseudoscientific if there are no Contacts or very few contexts in which the the the false the false prediction would be attributed to the theory This is part of a broader conception of the nature of Scientific knowledge or the scientific process According to which there's there's basically two stages to a scientific inquiry The first stage conjecture the second stage refutation Popper's idea is that what scientists do is first You know creatively ingenious ingeniously Propose theoretical conjectures they construct theories And hypotheses and then they test them in an attempt to refute the theory the main purpose of Empirical testing for Popper is falsification is rest is refutation not adding additional evidence not trying to confirm that our theory is true, but attempting to refute it and The history of science according to Popper can be seen as a series of conjectures and Refutations some conjectures last longer than others Some theories may go without refutation for a long time May be expanded and improved without refutation, but often you have According to Popper you have theories replaced by newer theories that may bear some resemblance to the old theory, but which Largely represent novel and broader sets of predictions Now this process of Conjecture and refutation and this notion that empirical testing is Largely a process of falsification or refutation Is part and parcel of Popper's commitment to inductive skepticism so remember We talked about the empiricists last time and David Hume was one who we consider an inductive skeptic he Raising certain problems of induction concluded that there was not really a logical justification for inductive inference and we saw the logical empiricists attempting to give various accounts of inductive inference and Encountering very difficult problems like the Ravens problem and the group problem in order to And they encountered these problems in the course of trying to come up with an account of induction and there were some significant limitations to their ability to do so rather than join the positivists or the empiricists in trying to Solve these problems Popper rather embrace the conclusion that Hume came to that that there ultimately is no logical justification for induction that that we can't generalize We can't confirm our scientific theories. We can only Say that they're refuted Or they have not yet been refuted There's a certain way in which that makes a lot of sense right because on the one hand we have a very clear Compelling account of deductive logic according to which general is that universal generalizations are easy to falsify But impossible to conclusively verify unless there's a very limited number of Instances of the generalization So, you know all Ravens are black is easy to confirm if you've got only 20 Ravens in the world but when you have An uncountable number of Ravens and More Ravens that will be born in the future that you can't count now logically, it's impossible to conclusively Demonstrate the truth of that generalization unless you can finally get all of the instances So that's compelling on the one hand on the other hand The uses to which we put science in engineering in medicine and application Sort of require us to distinguish between theories that are well-confirmed and those that aren't although Popper attempts to Address that in a way with his account of corroboration. It's hard to see how That account is going to work so that's a brief introduction to the to Carl Popper's philosophy of science How successful was Sir Carl's philosophy of science? Does it do a better job of representing science than the image given to us by logical empiricism? Well, I look forward to hearing what you think We'll certainly see implicit and explicit criticisms of Popper's views in future readings But for now we can I think we can think about the the pluses and minuses that we find in his views Ourselves and I look forward to talking to you about them in class tomorrow or Or on discord perhaps and I look forward to seeing you next time