 Hi there, welcome back to history and philosophy of science and medicine. I'm Matt Brown And I want to start today by talking about a very influential image of scientific knowledge and how it works, right? So according to this image, we have two really secure foundations for our knowledge. The first is our sensory experience. This is the sort of foundation for our knowledge about facts of the world, how things in the world are. And then the second is sort of what we might call logical connections between ideas, right? The foundation of our mathematical knowledge and perhaps other types of abstract or rational knowledge. Now there's a lot of disagreement about the details within this image, but I think that overall, it's a fairly widespread way of thinking about how science works that goes back a long time. And these are the core commitments of the philosophy we call empiricism. We associate with a number of historical figures including John Locke, George Barkley, David Hume, but I think we could also pull in many early modern scientists like Isaac Newton in some way into that empiricist way of thinking. Now this image of science was taken up and elaborated in the 20th century by the logical positivists or logical empiricists. The school of thought that began with thinkers like Moritz Schlick, Rudolf Karnapp, Otto Neurat, Carl Hempel, Hans Reichenbach, and a number of others. They brought to the core commitments of empiricism new tools from formal logic and an emphasis on language over psychological concepts like sensory experience and relations of ideas. So they transformed empiricism and their view of science had the following kind of core commitments. The view that science is essentially a system of statements or sentences that it was a body of knowledge that could be understood as a language or as a system of statements or sentences within a language. Now the language might have a very odd vocabulary, might include or be fully expressed in mathematical language, but nevertheless. Second, the core commitment is that any statement is understood as cognitively meaningful, that is, you might understand that as factually meaningful or having a meaning that could be true or false, only if it is empirically testable or is a logical tautology, or we might say a logical truth or a logical falsehood. And that notion of testability that's built into that notion of meaningfulness amounts to a kind of translatability into complexes of observation sentences which can then be checked by making observations. So in later forms of logical empiricism, that notion of testability might be sort of opened up to accommodate more indirect notions of testing, but in the earliest form it meant this translatability into observation sentences. Now along with these commitments, the logical empiricists accepted a kind of division of labor. They distinguished the context of discovery, the sort of messy actual happenings of science, from the context of justification, which they understood in a kind of logical abstract way, the relations of confirmation or logical support within the system of statements that science produces. The context of discovery was to be analyzed by historians, psychologists, maybe sociologists, and would look at all the things that went on as humans actually produce scientific knowledge, and all of which the philosophers of science could safely ignore as they focused on the context of justification and the analysis of the final products of science and their and their logical relations, right? Within this notion of the context of discovery, the philosophers of science had two main tasks. One is the logical analysis of scientific theories, right? A kind of interpretive activity in which they would take whatever scientists produced in terms of articles, in terms of research reports, in terms of textbooks, and they would kind of clean it up, rationally reconstruct it, understand the logical structure of it, and then the second task was the working out of a logic of confirmation that explains how evidence supports scientific theories. Now this means philosophers of science were effectively ignoring the scientific process, how knowledge was produced, in favor of taking the final results of science and analyzing aspects of them, primarily their structure and their justification, the language in which they were produced, the theoretical structures that they produced, and the way in which evidence was used to justify them. If we look at the second task, the sort of confirmation logic, that really took two forms. Analysis of confirmation really took two forms. One was the analysis of inductive inference and also what was called hypothetical deduction, and the second was the use of probability and statistics to build a kind of probabilistic confirmation theory. Now this first attempt to look at induction and hypothetical deduction generated probably the lion's share of work in mid to late 20th century philosophy of science. There are many difficult problems here having to do with how actually inductive generalization and what Peter Godfrey Smith calls explanatory inference, or we might call it called hypothetical deductive inference work, right? That is the sort of hypothesizing or positing of an explanation and then the derivation of empirical consequences from it. Problems like, this goes back all the way into classical empiricism with Hume's problem of induction. You know, how do we know that we can, how can we know that the future will be like the past without assuming that the future will be like the past, right? How can we understand the logical relationship between instances of empirical instances like this raven is black or this swan is white? To universal generalizations, all ravens are black. How do we understand the support there? It turns out to be really difficult and pose a lot of problems. I think it's fair to say that the kind of the kind of philosophy of science that looked at induction and hypothetical deduction in these ways is now considered something of a failure. That insofar as we want to analyze scientific confirmation or the way in which evidence supports theory and science, we're going to have to do it in some in some other different way. The second approach pursued by Rudolph Karnapp, the use of probability and statistics, although you know, Karnapp's own confirmation theories didn't get a lot of traction, as as Peter Gottfried Smith says in the book. In some sense, a practical version of this idea is on the right track, right? Scientists and statisticians over the course of the 20th century and into the present, more so than philosophers, although philosophers of science have played a role here, have developed accounts, increasingly nuanced accounts of statistical hypothesis testing and what's called Bayesian inference as well, that play really important roles in practical scientific methodology, as well as debates about how science ought to proceed. So, that aspect is really important and it's something that will actually take up in detail later in the semester when we start looking at problems of evidence in medicine and values in science. Many of the historians and philosophers of science we will read in the coming weeks present significant challenges to this traditional picture of science and to the division of labor that it entails. So let me just let me just re-articulate what the traditional picture of science involves. It involves a commitment to the idea that our knowledge of the world is grounded in our sensory experience and the logical connections of ideas that we can understand science as a system of sentences or statements that we can distinguish what kind of statements are cognitively meaningful in terms of empirical testability and logical truth or falsity logical tautology or contradiction and that we can understand testability as a relation of more theoretical sentences to observation sentences that which we can then directly check by making observations. This picture also is committed to an important distinction, the context of discovery, context of justification distinction which comes along with a division of labor between history of science on the one hand and other things like psychology of science, sociology of science, which study how science actually took place, the actual processes by which science is done, and the philosophy of science which looks at the logical sort of analysis of the products of science and how and whether those products are justified by evidence. It's not to say that there's not something going on about some of these ways of thinking about science, but there are a lot of problems that we'll talk about as we look at problems of induction, explanation, confirmation today, and that many of our thinkers in subsequent weeks will point to serious concerns about and we'll learn to think through some other images of science that are also more conducive to the integration of history and philosophy. So those are my sort of initial notes on empiricism and logic in history and philosophy of science, and I look forward to seeing you in class and talking to you next week. Bye.