[cross-posted at Footnotes on Epicycles]
On Wednesday, we talked about Kuhn's claim that different paradigms are incommensurable, and today we talked about the considerations which might convince scientists to shift from the old paradigm to a new one. Kuhn characterizes the shift as a conversion experience, but not one that is totally unmotivated by reasons. Kuhn reviews a whole range of possible reasons, including puzzle-solving power, precision, novel prediction, and simplicity.
He insists that none of these reasons are necessarily decisive, however. He writes that
paradigm debates are not really about relative problem-solving ability.... Instead, the issue is which paradigm should in the future guide research on problems many of which neither competitor can yet claim to resolve completely. A decision between alternate ways of practicing science is called for, and in the circumstances that decision must be based less on past achievement than on future promise. (p. 156)Because a paradigm serves to guide normal science, accepting a paradigm means committing to do normal science in that way. So the choice is forward-looking, while all of the reasons are backward-looking. So, one might say, the choice of paradigm is strategic rather than simply evidential.
While discussing this passage, I realized that the conclusion does not rely on incommensurability at all. Rather, it just relies on the problem of induction: Past performance of a paradigm provides no guarantee of future results. So proceeding with one paradigm rather than the other is a kind of gamble. Reasonable people with different hunches or different tolerance for risk might disagree about which way to go.
This allows for a philosophically conservative reading of Kuhn which accepts that revolution is different than normal science, because different paradigms would guide scientific practice in substantially different ways. The conservative reading also accepts that the choice between paradigms cannot be determined by the relevant reasons, especially during the period of crisis.
The conservative reading isn't adequate as a reading of Kuhn, because it accepts those things without any appeal to incommensurability. The change between paradigms might be like a conversion experience, as Kuhn would have it, because some strategic choices are; consider choosing a career, choosing to get married, or choosing whether or not to have children. But it might instead be a self-conscious choice, like choosing between mutual funds for your retirement account.
I think that this recommends the conservative reading as a philosophical position, even if it disqualifies it as a reading of Kuhn. The description of normal science and crisis is the really insightful part of Structure, while the stuff about incommensurability is the most problematic.
It occurs to me that what I've called here the conservative reading of Kuhn, in which underdetermination comes from the problem of induction rather than incommensurability, looks a lot like Lakatos' Methodology of Scientific Research Programmes. We're doing Lakatos next week in class, so I'll see if that idea holds up.