Klaas Landsman

Radboud University

Day 2 (April 12) @ 16:15 – 17:00 Keynote

In praise of (good) definitions

Abstract: Good definitions are a central ingredient of good mathematics (as well as of good philosophy). We trace the origin of this concept back to Socrates and Plato, draw attention to their importance in Newton’s Principia from 1687 and in early modern science in general, and move on to the 20th century. Here we find highlights ranging from Hilbert to Penrose. Apart from history and examples, also the nature of good definitions will be analyzed. If we are to instill the virtues of mathematical thinking into science, or even into thought in general, this aspect of mathematical precision seems on a par with the concept of proof. Thus the fact that definitions are usually introduced without much context or explanation, even to students of mathematics,(as are proofs, expect in formal logic), needs to be remedied. This talk is a first attempt to do just that. 


Prof.dr. NP (Klaas) Landsman} has been Professor of Mathematical Physics since 2001, initially at the University of Amsterdam and since 2004 at Radboud University in Nijmegen. His PhD in theoretical physics (from the University of Amsterdam) dates from 1989, after which he spent the years 1989-1997 at the University of Cambridge (with one year, 1993-94, at the University of Hamburg). He is a former EPSRC Advanced Research Fellow (UK), Alexander von Humboldt Fellow (Germany), KNAW Research Fellow (Netherlands) and NWO Pioneer (ditto). In 2011 he received a TOP-GO award from NWO. He is a member of both the KNAW (2019) and the KHMW (2021). In 2020 he won the FQXi Essay Contest 2019-2020 on Undecidability, Unpredictability and Unpredictability, and in 2022 he won the Spinoza Prize (the highest scientific award in the Netherlands). Besides his core work in theoretical physics and mathematical physics, he is also active in pure mathematics and in the history and philosophy of physics. Until now he has mainly worked on the mathematical and philosophical foundations of quantum theory and general relativity, but he is currently moving towards statistical mechanics and the thermodynamics of black holes. He has authored four scholarly monographs, two popular science books, nearly one hundred peer-reviewed papers and book chapters, and nearly 50 popular articles and opinion articles in newspapers. Landsman has trained 15 PhD students and 30 Master’s students and many of his former students work in academia. He was co-founder of the Institute for Mathematics, Astrophysics and Particle Physics (IMAPP) at Radboud University Nijmegen, of the national mathematics cluster Geometry and Quantum Theory (GQT), of the Dutch Institute for Emergent Phenomena (DIEP), and of the National Science Agenda route Building Blocks of Matter and Foundations of Space and Time, all of which still thrive. He is currently working on the construction of a Radboud Center for Natural Philosophy.

Photo credits: Jitse Boots