Marius Stan is Associate Professor of Philosophy at Boston College. He works in history and philosophy of science, with an emphasis on classical physics. He is co-author, with Katherine Brading, of Philosophical Mechanics in the Age of Reason (Oxford), and author of Kant’s Natural Philosophy (Cambridge). Christopher Smeenk is Professor of Philosophy and Director of the Rotman Institute at Western University, Ontario. He works in general philosophy of science, philosophy of cosmology, and history of physics. In addition to numerous articles, he is co-editor of the Oxford Handbook of Newton (with Eric Schliesser) and co-author of The Aim and Structure of Cosmological Theory (with James Owen Weatherall).