I offer an alternative account of the relationship of Hobbesian geometry to natural philosophy by arguing that mixed mathematics provided Hobbes with a model for thinking about it. In mixed mathematics, one may borrow causal principles from one science and use them in another science without there being a deductive relationship between those two sciences. Natural philosophy for Hobbes is mixed because an explanation may combine observations from experience (the ‘that’) with causal principles from geometry (the ‘why’). My argument shows (...) that Hobbesian natural philosophy relies upon suppositions that bodies plausibly behave according to these borrowed causal principles from geometry, acknowledging that bodies in the world may not actually behave this way. First, I consider Hobbes's relation to Aristotelian mixed mathematics and to Isaac Barrow's broadening of mixed mathematics in Mathematical Lectures (1683). I show that for Hobbes maker's knowledge from geometry provides the ‘why’ in mixed-mathematical explanations. Next, I examine two explanations from De corpore Part IV: (1) the explanation of sense in De corpore 25.1-2; and (2) the explanation of the swelling of parts of the body when they become warm in De corpore 27.3. In both explanations, I show Hobbes borrowing and citing geometrical principles and mixing these principles with appeals to experience. (shrink)

The Italian philosopher Giambattista Vico developed a theoretical framework for the study of human sciences that exerted a strong influence on psychology and other human sciences. He backed the unity of the knowledge about human mind and culture, including history, linguistics, philosophy, philology, epistemology, psychology, and for the first time proposed a method for their study that he ambitiously called ‘new science’. The article presents an overview of Vico’s thought and discusses some of the main axioms of his theoretical system. (...) His critique of Cartesianism as the alternative epistemology he outlined is put forward as a thoughtful tool for reflection on contemporary psychological science. This retrospective look at Vico’s idea would finally provide useful insights for a programmatic view on cultural psychology. (shrink)