[Trends in Evolutionary Biology 2009; 1:e1] [page 1]

Charles Darwin has had more impact on biological sciences, and society generally, than any other 19th century biologist. Yet his modus operandi as a scientist is poorly known by evo-lutionists, and often seriously misinterpreted. Two important aspects of his reasoning dis-cussed here are his hypothetico-deductive approach and his search for mechanisms to explain past events. A wide range of state-ments from his autobiography and letters show that he worked explicitly in the hypothetico-deductive model. The extracts include strong statements that theories were essential even to know what data to collect; to hold theorie