I just read Inventing Temperature by Chang. It is, as may be expected from the title, a book on the history of temperature, focusing on the development of thermometry. Every chapter is divided into two parts: historical narrative and philosophical analysis. There are elements of each in both parts of the chapters though. I am going to comment on a few themes from the book.

One is the epistemic problem of setting up a scale on which to measure temperature. This requires fixed points to calibrate against. Knowing that a certain phenomenon always happens at a certain temperature would require knowing what temperature that phenomenon happens at. This requires having a calibrated thermometer already to hand since exact temperature is not an observable phenomenon and outside a fairly narrow range it isn’t observable with any sort of even rough accuracy. The response to this circularity that Chang finds in the historical narrative is a process of iterative improvement. First some substances are found that roughly agree and we can calibrate according to our senses. Based on this more precise devices can be constructed, still using ordinal comparisons. If things go well, new devices can be constructed on the basis of those with a numeric scale that has a physical meaning. Chang is hesitant to follow Peirce in taking this iterative development to be linked to truth although he notes the similarity.

I want to note about this is an affinity with some of Mark Wilson’s views. In particular, Wilson’s suggestion to view agents as measuring devices themselves. They don’t have nice numeric scales associated with the various physical properties that they are responding to, but the measuring capabilities are enough to cope with the world. Chang’s suggestion goes along with this and ties it in a clear way to the development of science: our rough measuring capacities are sufficient to start the iterative development of measuring devices as needed by various scientific enterprises. (This sounds somewhat commonsensical.) It is an aspect that seems to go missing somewhat in discussions of perception.

In Wandering Significance, Wilson says that he thinks Gupta and Belnap’s revision theory of truth and theory of circular definitions can be used to explain various episodes in the history of science. He doesn’t provide examples, which is a pity since my historical ignorance left me wondering what he had in mind and how that story would go. Chang’s picture of iterative development provides a clear example. The concept of temperature used, the operative core of it, is clearly circular. Starting with some initial hypotheses about values based on our perceptual capacities, an extension is roughly determined which forms the new basis for further revisions. Repeat. There are some rough edges to this though. This revision process is clearly not taken to the transfinite, or even that far into the finite. The range of starting hypotheses and values is fairly constrained, so the extension, if any, that is constant under all initial hypotheses will not be determined. Despite these incongruities, the theory of circular definitions looks to be applicable. If this is a paradigm case, then it would vindicate Wilson’s claim since similar incidents of setting up a system of measuring devices, measurement operations and theoretical concepts arise often enough in the recent history of science, I would expect. Even if the particular sort of system involving measuring devices does not, Chang indicates that systems of circular concepts arise and are developed through something like the iterative process that he sketches. If this is right, then it seems like one should pay more attention to circular concepts and conceptual development than has been done lately.