Kati Kish Bar-On is a postdoctoral research fellow in the Science, Technology and Society program at MIT. Her research lies at the intersection of the history and philosophy of mathematics with the philosophy of social science. She combines historical examinations of primary sources with methods from philosophy of science and philosophy of psychology to provide new ways of understanding the nature of mathematics as situated, on the one hand, in individual thinking, and on the other, in social reality. This is her first book manuscript, based on extensive research conducted over eight years. Funding for her research endeavors has been provided by the STS program at MIT, the European Commission Horizon Europe (Marie Sklodowska-Curie Actions fellowship, Project number 101108426), the Rothschild foundation, and Tel Aviv University. Kati's scholarly contributions can be found in reputable publications such as Philosophy of Science, Synthese, PNAS Nexus, Studies in History and Philosophy of Science, Perspectives on Psychological Science, Philosophical Transactions of the Royal Society B: Biological Sciences, Science in Context, and Behavioral and Brain Sciences.