You know, Hugo, sometimes, you really make my head hurt.
Things that I had taken for granted seem much less obvious after reading your essays and posts.
I'm taking as a test case the conflict between the theories of evolution (broadly speaking, descent with modification) and the so-called theory of intelligent design, as a way of evaluating the philosophy of science issues that you have raised -- partly to deepen my understandinig of these issues, but also partly to decide if I really ought to be agnostic
about deciding between unplanned evolution and ID.
Maybe you can help me untangle this.
Most biologists would say there is no problem here, because the theory of ID is not a theory
-- and hence (presumably) none of the problems that you have discussed, like undetermination or falsificationism, arise. On this view, ID is vacuous, because it predicts nothing and is really just a question-begging argument, assuming the existence of ID when it must be proved.
However, ID proponents would dispute this. One example is Michael Behe. Behe would say that the theory of intelligent design predicts the existence of irreducibly complex structures -- and he cites, as an example, the flagellum. Behe argues that since the flagellum is irreducibly complex, it must have been designed. A failure to find irreducibly complex structures, Behe would presumably concede, would have falsified ID.
But, as you explained in another essay, falsificationism is a dubious project. So by this reasoning, even if we failed to find such structures, Behe would be justified in tenaciously pursuing his theory (if it is a theory). The issue is made even more complex by the fact that biologists insist that we have
failed to find such structures -- that Behe is simply wrong in citing the flagellum as irreducibly complex, and that moreover, evolutionary theory perfectly accounts for the way that seemingly IC structures in fact arose in a stepwise fashion, guided by little more than random chance shaped by natural selection.
Another ID prediction is due to Dembski, who argues that a structure in nature is designed if it displays specified complexity
-- a complexity that could not have arisen by chance processes. Other scientists say they have shown that his entire premise is flawed, a flaw arising from Dembski's misunderstanding of statistics and probabilty. But the point, I think, is that Dembski can at least say he has produced a theory, and that even if others claimed to have falsified its predictions, isn't Dembski entitled to tenaciously pursue his project, and aren't we on shaky ground in claiming that it (or any theory) is ever really falsified? If these really are two competing theories, (evolution vs. ID) aren't they then underdetermined? And should we be agnostic in choosing between them? Or is the better strategy to choose the theory that is more parsimonious, or more aesthetically appealing or makes more interesting predictions? And if that's the case, I would choose descent with modification and reject ID, but couldn't one argue that my choice is really nothing more than a matter of personal taste?
To go back to the theory of descent with modification: Biologists contend that one of the strongest selling points of evolutionary theory is precisely that it is so vulnerable to falsification. For example, so far as I can tell, it seems obvious that if mammal fossils started turning up in precambrian rocks, descent with modification is falsified. (Even with all the problems of falsification that you discussed, though it's possible I'm missing something.) That's because evolutionary theory relies on nested heirarchies of species -- common descent, with mammals much "higher" on the phylogenetic tree than precambrian species. In other words, it seems the theory of descent with modification would collapse by definition
if such fossils were found. That is, there does not seem to be any conceivable ceteris paribus
clause to fall back on here.
OK, now I'm going to take a breather. I hope my confusion had made sense.