Galileo Galilei

(1564–1642)

Italian scientist. Although Galileo's distinction belongs to the history of physics and astronomy rather than philosophy, his mature philosophy and methodology of science, particularly as derived from the Dialogue Concerning the Two Chief World Systems (1632) and the Dialogues Concerning Two New Sciences (1638), have been much debated. Galileo unquestionably holds that science based on observation is the true source of knowledge of the physical world, as opposed to traditional authority and philosophical speculation. He also advocates a becoming modesty concerning what we know about nature, in opposition to the dogmatic certainties of much late medieval thought. But within science the relative roles of mathematics, a priori reasoning, pure observation, and model-building are not so clear, and Galileo has been seen as an example of Platonistic rationalism as well as of Aristotelian naturalism. Particular doctrines for which he is known in philosophy include the distinction between primary and secondary qualities, and the relativity of motion. The conception of the world associated with modern science is frequently referred to as the Galilean world view.