Birch & Ehrlich: Evolution “outside of empirical science”
“Our theory of evolution has become, as Popper described, one which cannot be refuted by any possible observations. Every conceivable observation can be fitted into it. It is thus ‘outside of empirical science but not necessarily false’. No one can think of ways in which to test it.”
Charles Birch and Paul Ehrlich, Evolutionary history and population biology, Nature 214:352, 1967.