Natural History and Natural Philosophy: Robert Boyle and the Modification Theories of Colours

This paper focuses on Robert Boyle's Experiments and Consideration Touching Colours (1664), one of the main sources of Newton's early studies and experiments on colours. Newton scholars and historians of early modern optics have placed great emphasis on Newton's reading of Boyle's experimental history of colours, but little attention has been paid to the development of Boyle's views on colours and light in the context of his natural philosophy, and of the physical theories of light and colours before Newton. This contribution aims at being a first step towards filling this gap, placing Boyle's book on colours in the context of his experimental programme for the construction of histories of qualities. More than other works, its content reveals Boyle's effort into testing previous theories and its strategy in dealing with problems that afflicted both ancient and modern assumptions on natural phenomena. He accepted the basic assumptions of the contemporary mechanist theories of modification, and deployed experimental evidence to confute chemical and Aristotelian theories of colours. Despite that, Boyle did not concentrate on the solution of a definite problem. Whenever he faced with a hypothesis, he set up an experiment to test it, without drawing any definite conclusion. Firmly convinced of the explanatory force of the mechanical philosophy, he let Newton drew all the consequences of his experiments.