Darwin followers never said that their theory has no exceptions. Here are a few typical claims:
“Unlike the case in physics, the predictive power of a model in biology is quite low. It seems to us that if the prediction (e.g., a phylogenetic tree reconstructed) of a model is correct in 80% of the cases, it is a good model at least at the present time.”
Masatoshi Nei and Sudhir Kumar, 2000, Molecular Evolution and Phylogenetics, p85.
“any rule an evolutionary biologist can come up with, nature can break.”
From Professor Ken Weiss’s Blog page of July 13, 2009, http://ecodevoevo.blogspot.com/2009/07/rules-of-nature.html
A common sense and logical view of mine on why any theory must not allow a single contradiction in order to qualify as scientific or testable:
In mathematics or physics, one exception is sufficient to doom any theory. The science of biology or any scientific discipline for that matter should not be held to a lower standard. When one allows exceptions, one has effectively and automatically rendered the theory non-testable and non-scientific. Think about it: if a test turns out to be against the theory, would the theory still stand as correct? Yes, if one allows exceptions. Thus, such a theory can never be falsified by the scientific method. That theory would be no different from a false theory that happens to explain a fraction of nature while being contradicted by the rest. The only way to distinguish a true theory from a false or incomplete one is to see if it has not a single factual exception within its domain of application or relevance.
The worst theory possible would still be able to explain at least one factual observation, namely, the fact itself that directly provoked the theory or the tautology. For example, apple falls because it is the intrinsic nature of apple to fall. Thus, to be able to explain a small fraction of all relevant facts while being contradicted by the rest is not evidence of a true theory but is evidence of an incomplete or false theory.
I have no patience with such typical self-serving and self-deceiving claims that you don’t expect a theory of evolution to have no contradictions since most things are chance. The one thing that all genuine science like mathematics and physics have taught us is that it would take a miracle for an incomplete theory to have no contradictions and it would equally take a miracle for a complete theory to encounter a single contradiction in nature. The difference between truth and falsehood is not quantitative or measured by the difference in the number of contradictions but is qualitative.
There can be countless incomplete or false theories with each accounting for a few facts but there can only be one unique true theory that accounts for all facts within its domain of application. Until evolutionary biology has such a theory that has not a single contradiction, it is not real science. But I still view the daily work of biologists as scientific even if being misguided by an incomplete theory because the facts that they collect will be useful for looking for the true theory and fact collection rather than theory building is what they do for a living. In this sense, the taxpayers’ money is well spent indeed.
Newton physics does not work in the microworld and Newton followers have no trouble admitting it. Darwinism would not have a single exception if it is limited to microevolution such as drug resistance in bacteria. It only encounters exceptions when being applied to domains such as macroevolution where it is irrelevant and false. Darwinists could easily meet the no contradiction standard if they could just be honest and specific about where their theory works and where it does not.