After the last post on incommensurability, Mike provided a link to a more theoretical discussion of Lakatos’s and MacIntyre’s objections to Kuhn. In my opinion, the linked article is too abstract to provide any guidance. The author favors MacIntyre’s idea that a scientist moves from one paradigm to another when the old paradigm fails to meet its own objectives. But it would be nice to have good examples of this (maybe MacIntyre provides these; I haven’t looked up his discussion). Initially, I am skeptical that this ever happens; smaller theories reach clear dead ends, but paradigms don’t.

So what brings a scientist to switch from one paradigm to another? So far as I can see, it is the potential for new fields of ideas (and publications). This has been happening in the field of chaos theory. Somebody develops a new toolkit, and pretty soon people start seeing ways to apply those tools to all sorts of different phenomena, and they publish like crazy. No one wants to get left behind. It’s not that the new applications are clearly better, or that the old business is clearly worse. It’s just that the new is new and the old is old. And the “new” isn’t merely arbitrary or hollow or fake: the new applications show something, or do something, that the old applications couldn’t, so something new is being learned and uncovered.

What becomes critical is whether there is something we really need to get done that only the old application can provide. With Ptolemy/Copernicus, eventually the answer became “no” — everything we needed Ptolemy for could be done by Copernicus (at least after Kepler). But with chaos, the answer is still “yes” — we still need linear dynamics and Newtonian determinism for lots of tasks, so chaos will not be taking over anytime soon. In the meantime, it is a fertile ground for new publications.

Sometimes, I imagine, the old paradigm gets discarded not because the new one can do everything it could do, but because our needs and interests change. So we no longer need the old services, thank you very much. So maybe one “need” keeping Ptolemy around was our interest in astrology. As that need faded, so too did Ptolemy. (I’m making up that example; I don’t know the history of astrology well enough to know if this is indeed the case.)

So can we say that new paradigms are always “true-er”? Not exactly. We can say that they are a better fit for our needs (and they couldn’t do that without being linked up to truth in some way), and the old paradigms no longer provide that fit.