. . . Then Darwinian Evolution is untestable. If intelligent design is unfalsifiable, then Darwinian evolution is unprovable.
1) Darwinian evolution isn't really accepted by any specialists in evolutionary theory; it's just a convenient term for a vastly more complex, interdisplinary field involving multiple theories.
2) Evolutionary theory has successfully constructed models of biological processes which have predictive power. It isn't simply an explanation, but a theory or theoretical framework within which we have been able to develop and test hypotheses about everything from the life sciences to computational intelligence paradigms.
3) "Intelligent design" lacks predictive power, offers
post hoc explanations rather than models, and has increasingly lost ground as its claims have shown to be false.
4) Nothing in "Logic 101" supports the inference that given two opposing views, epistemology dictates something like a one-to-one relationship between evidence or the possibility of evidence for one and corresponding evidence for the other.
They're opposing answers to the same question
So is the answer that life arose from smurfs, that we're all in the Matrix, that this is all your dream, that life arose through the magic, and so on. There are infinitely many opposing answers to the any specific answer, and thanks to the properties of infinitely many options the probability that any are
a priori likely is 0. However, evolutionary theory has vast amounts of evidence and entire fields supporting it.
Any evidence for one will be evidence against the other.
Wrong. Genetics and epigenetics are evidence for evolutionary theory but aren't evidence against intelligent design, which is deliberately constructed so as to not make this the case.
Any proof of one will be proof against the other. proving one will falsify the other (and vice versa).
When Darwinists say we can't falsify the claim that biology is a product of design, they're unwittingly confessing that they can't prove biology is the product of blind nature.
Or they have some basic familiarity with epistemology, the philosophy of science, and what "proof" means to scientists.
The only reasonable conclusion is that either both are science, or neither is science.
How unfortunate.