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Astral Codex Ten Podcast

Jan 20, 2019

Thanks to everyone who commented on the review of The Structure Of Scientific Revolutions.

From David Chapman:

It’s important to remember that Kuhn wrote this seven decades ago. It was one of the most influential books of pop philosophy in the 1960s-70s, influencing the counterculture of the time, so it is very much “in the water supply.” Much of what’s right in it is now obvious; what’s wrong is salient. To make sense of the book, you have to understand the state of the philosophy of science before then (logical positivism had just conclusively failed), and since then (there has been a lot of progress since Kuhn, sorting out what he got right and wrong).

The issue of his relativism and attitude to objectivity has been endlessly rehashed. The discussion hasn’t been very productive; it turns out that what “objective” means is more subtle than you’d think, and it’s hard to sort out exactly what Kuhn thought. (And it hasn’t mattered what he thought, for a long time.)

Kuhn’s “Postscript” to the second edition of the book does address this. It’s not super clear, but it’s much clearer than the book itself, and if anyone wants to read the book, I would strongly recommend reading the Postscript as well. Given Scott’s excellent summary, in fact I would suggest *starting* with the Postscript.

The point that Kuhn keeps re-using a handful of atypical examples is an important one (which has been made by many historians and philosophers of science since). In fact, the whole “revolutionary paradigm shift” paradigm seems quite rare outside the examples he cites. And, overall, most sciences work quite differently from fundamental physics. The major advance in meta-science from about 1980 to 2000, imo, was realizing that molecular biology, e.g., works so differently from fundamental physics that trying to subsume both under one theory of science is infeasible.

I’m interested to hear him say more about that last sentence if he wants.

Kaj Sotala quotes Steven Horst quoting Thomas Kuhn on what he means by facts not existing independently of paradigms:

[Kuhn wrote that]:

A historian reading an out-of-date scientific text characteristically encounters passages that make no sense. That is an experience I have had repeatedly whether my subject is an Aristotle, a Newton, a Volta, a Bohr, or a Planck. It has been standard to ignore such passages or to dismiss them as products of error, ignorance, or superstition, and that response is occasionally appropriate. More often, however, sympathetic contemplation of the troublesome passages suggests a different diagnosis. The apparent textual anomalies are artifacts, products of misreading.

For lack of an alternative, the historian has been understanding words and phrases in the text as he or she would if they had occurred in contemporary discourse. Through much of the text that way of reading proceeds without difficulty; most terms in the historian’s vocabulary are still used as they were by the author of the text. But some sets of interrelated terms are not, and it is [the] failure to isolate those terms and to discover how they were used that has permitted the passages in question to seem anomalous. Apparent anomaly is thus ordinarily evidence of the need for local adjustment of the lexicon, and it often provides clues to the nature of that adjustment as well. An important clue to problems in reading Aristotle’s physics is provided by the discovery that the term translated ‘motion’ in his text refers not simply to change of position but to all changes characterized by two end points. Similar difficulties in reading Planck’s early papers begin to dissolve with the discovery that, for Planck before 1907, ‘the energy element hv’ referred, not to a physically indivisible atom of energy (later to be called ‘the energy quantum’) but to a mental subdivision of the energy continuum, any point on which could be physically occupied.

These examples all turn out to involve more than mere changes in the use of terms, thus illustrating what I had in mind years ago when speaking of the “incommensurability” of successive scientific theories. In its original mathematical use ‘incommensurability’ meant “no common measure,” for example of the hypotenuse and side of an isosceles right triangle. Applied to a pair of theories in the same historical line, the term meant that there was no common language into which both could be fully translated. (Kuhn 1989/2000, 9–10)

While scientific theories employ terms used more generally in ordinary language, and the same term may appear in multiple theories, key theoretical terminology is proprietary to the theory and cannot be understood apart from it. To learn a new theory, one must master the terminology as a whole: “Many of the referring terms of at least scientific languages cannot be acquired or defined one at a time but must instead be learned in clusters” (Kuhn 1983/2000, 211). And as the meanings of the terms and the connections between them differ from theory to theory, a statement from one theory may literally be nonsensical in the framework of another. The Newtonian notions of absolute space and of mass that is independent of velocity, for example, are nonsensical within the context of relativistic mechanics. The different theoretical vocabularies are also tied to different theoretical taxonomies of objects. Ptolemy’s theory classified the sun as a planet, defined as something that orbits the Earth, whereas Copernicus’s theory classified the sun as a star and planets as things that orbit stars, hence making the Earth a planet. Moreover, not only does the classificatory vocabulary of a theory come as an ensemble—with different elements in nonoverlapping contrast classes—but it is also interdefined with the laws of the theory. The tight constitutive interconnections within scientific theories between terms and other terms, and between terms and laws, have the important consequence that any change in terms or laws ramifies to constitute changes in meanings of terms and the law or laws involved with the theory (though, in significant contrast with Quinean holism, it need not ramify to constitute changes in meaning, belief, or inferential commitments outside the boundaries of the theory).

While Kuhn’s initial interest was in revolutionary changes in theories about what is in a broader sense a single phenomenon (e.g., changes in theories of gravitation, thermodynamics, or astronomy), he later came to realize that similar considerations could be applied to differences in uses of theoretical terms between contemporary subdisciplines in a science (1983/2000, 238). And while he continued to favor a linguistic analogy for talking about conceptual change and incommensurability, he moved from speaking about moving between theories as “translation” to a “bilingualism” that afforded multiple resources for understanding the world—a change that is particularly important when considering differences in terms as used in different subdisciplines.

Syrrim offers a really neat information theoretic account of predictive coding: