Axiomatic Thinking I (PDF)

Fernando Ferreira is Professor of Mathematics at Universidade de Lisboa. He received his Ph.D. at Pennsylvania State University in 1988 under the direction of Stephen Simpson. He was a Fulbright Scholar at Harvard University (Spring 2004) and Tinker Visiting Professor at Stanford University (Fall 2009). He has written papers on weak systems of arithmetic and analysis, proof theory (especially functional interpretations) and the philosophy and foundations of mathematics. He also wrote two papers on the problem of truth in Parmenides and Plato. He is a corresponding member of the Academia das Ciências de Lisboa.
Reinhard Kahle is Carl Friedrich von Weizsäcker Professor of Philosophy and History of Science at the University of Tübingen. Previously he held professorships in Mathematics at the University of Coimbra and at the Universidade Nova in Lisbon, finally becoming full professor in Mathematical Logic. He is a fellow of the Académie Internationale de Philosophie des Sciences. His main research interests are in proof theory and the history and philosophy of modern mathematical logic, in particular, of the Hilbert School. He has (co-)edited more than ten books and special issues such as, for instance, Gentzen's Centenary: The quest for consistency (Springer, 2015) and The Legacy of Kurt Schütte (Springer, 2020), both together with Michael Rathjen.


Giovanni Sommaruga studied philosophy and philosophical and mathematical logic at the University of Freiburg (Switzerland), Stanford University and the University of Siena. In 1996 he became assistant professor in logic and philosophy of science at the Albert Ludwig University Freiburg (Germany), and since 2008 he has been a senior scientist in the philosophy of the formal sciences (logic, mathematics, theoretical computer science) at ETH Zurich. His main research interests are in the philosophy and foundations of mathematics, the history of mathematical logic, and more recently the history of computability and