ABSTRACT
In 1906, J. Arthur Thomson, the Scottish biologist and Regius Professor of Natural History at the University of Aberdeen, published a short book on Herbert Spencer's life and biological ideas. According to Thomson, there was one term that summed up Spencer more than any other: 'arch-heretic'. The reason was that there were so many things Spencer was against, including theology, metaphysics, monarchy, 'molly-coddling legislation', classical education, socialism, war and the German biologist August Weismann. Marshall's decision to expunge the inheritance of acquired characteristics from Principles of Economics in 1895 is a moment of great significance when it comes to understanding Spencer's relationship with the biological sciences, the social sciences and the areas where the two intersect. Far from being a one-off, Marshall's decision to rewrite the details of a theory that borrowed from biology, rather than rethink the transaction entirely, in light of changing specialist opinions was repeated frequently around 1900.
