In response to this blast from the past about Kuhnian scientific revolutions, SteveG has an interesting discussion about the inadequacy of Popperian falsification for understanding paradigm shifts, or to use Imre Lakantos’ phrase “research programme” (italics mine):
Imre Lakatos was a student of Popper’s who also found certain things about Kuhn’s view deeply attractive. He realized the problems with the use of falsifiability of individual hypotheses as a criterion of demarcation for science that arose from Kuhn’s insights. but he also saw one of the glaring problems with Kuhn’s system. If a paradigm is a worldview and defines the questions, means of answering them, and what counts as acceptable answers, then all of rationality resides within the paradigm. As such, there can never be good reason to move from one paradigm to another as reasons only make sense within a paradigm.. There is no way to comparison shop for paradigms and so paradigm shift is akin to religious conversion.
Lakatos used Popper to solve this problem in Kuhn. Popper pointed out that falsified propositions could be saved by the use of ad hoc hypotheses and ruled them out as not allowable. For Kuhn, they are allowable. Lakatos’ insight was to reformulate Kuhn so that while they are permitted, they are a liability to theory acceptance. And research programme (as he renamed paradigms) could be saved by tweaking some other part of the theory, but when your tweak limits the relative testability (making less falsifiable in a sense), it becomes “degenerate.” When the research programme is able to explain more and more without ad hoc modifications, it is seen to be progressive. Kuhn is right (and Popper wrong) that you are never forced to rule out any theory, it can always be saved from problematic data and still be scientific. But Popper was right (and Kuhn wrong) that the ad hoc manner of saving it doesn’t come with a rational price.
As such, when we look at Intelligent Design and Darwinian Evolution, we have two research programmes that can be maintained regardless of the data. But it happens that ID is quite degenerate requiring all kinds of patches that do not increase its independent testability to account for observable phenomena. Evolutionary theory, on the other hand, is an unbelievably progressive research programme that accounts for a staggering amount of data ranging from macro-ecological facts, to micro-level genetic facts to geological facts. Darwinian evolution is testable in so many, many ways and in the overwhelming number of them easily accounts for observations. Are there anomalies? Of course. Every theory has anomalies. Will some of them be resolved with the addition of facts now unknown? Sure. Will others force us to rethink parts of the theory as it is now accepted? No doubt. Are there some that will cause the entire research programme to become degenerate and make it less than rational to cling to? Possible, but I’m a better bet to win the Tour de France next year.
One minor quibble is that I don’t think ID requires “all kinds of patches”–it relies on one fundamentally unknowable patch: the mode of action of a Designer. In that sense, ID can not be addressed within the research programme of science as a whole (as opposed to evolutionary biology).
This allows me to stumble into one of my philosophy of biology pet peeves: despite the popular acceptance of Popperian falsification, much of science actually uses a likelihood framework: hypotheses, big or small, are compared to one another to determine which hypothesis is the most likely. When examined from this perspective, ID still fails: I can’t place a likelihood estimate on the actions of an Intelligent Designer. By comparison, if we were to find that, overwhelmingly, most of the diversity observed in natural populations is not due to natural selection (i.e., only one in thousands of cases studied), then the theory of evolution by natural selection, while not ‘falsified’ does a very poor job of explaining natural diversity, and is an unlikely explanation.
Suffice it to say, natural selection is pretty likely…..