Karl Popper and evolution
The philosopher of science, Karl Popper, who did so much to formalise the scientific method as hypothesis testing and falsification, notoriously suggested that evolution was not a scientific theory because it was not testable. “Darwinism is not a testable scientific theory, but a metaphysical research program” (Unended Quest, 1976). However, he later retracted this view and provided a cogent and convincing argument for how evolutionary theory is a scientific one.
The two platforms of science for Popper were the formulation of bold, challenging hypotheses and testability. The former has played a major part in human evolutionary studies, while the latter has posed challenges as it has for all historical sciences.