‘Our theory of evolution has become…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. Ideas, either without basis or based on a few laboratory experiments carried out in extremely simplified systems have attained currency far beyond their validity. They have become part of an evolutionary dogma accepted by most of us as part of our training.

Paul Ehrlich (Professor of Biology, Stanford University) and L. Charles Birch (Professor of Biology, Sydney University). Nature, April 22, 1967. p.352.