This open access monograph presents an in-depth study of the problem of how agency fits into the physical world. In particular, the authors focus on agency as a precondition of free will. They present a detailed and physically well motivated formal model to anchor their philosophical discussion. Coverage brings together perspectives from physics, computer science, and different branches of philosophy. The book describes the agency model of Projective Simulation, its physical realisability and its quantum extensions. It situates this model within the discussion of agency in philosophy and in Artificial Intelligence. In addition, the authors highlight the role of agency in Quantum Mechanics itself, recently stressed by the Bayesian-inspired interpretation of Quantum Mechanics, QBism. They provide a comprehensive exposition of Quantum Mechanics and a reflection on the embodied nature of agents. (Quantum) indeterminism turns out to be a key resource for Projective Simulation, and for agency in general. This establishes a novel connection between agency and phenomenology. Overall, the book provides a coherent picture of agents as persisting physical entities endowed with active capacities. Such an explanation does not necessarily settle the question of the actual empirical basis of our human agency. It does, however, show that a coherent notion of agency is possible within a modern scientific world-view.
Hans J. Briegel is Professor of Theoretical Physics at the University of Innsbruck, Austria. His academic career includes postdoctoral positions at Harvard University, Texas A&M University, and the University of Innsbruck. He was one of the founding directors of the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences. He has held visiting positions at the Universities of Bristol and Konstanz and at Tsinghua University. Briegel’s main research lies in quantum information science, where his name is associated with concepts such as the one-way quantum computer, the quantum repeater, and quantum reinforcement learning. Beyond his research in quantum physics, he has also been involved in many interdisciplinary projects. He has received research grants and honors including an ERC Advanced Grant (2022), the Wittgenstein Award of the Austrian Science Fund (2023) and the Erwin Schrödinger Award of the Austrian Academy of Sciences (2024). In 2020 he was elected Fellow of the European Laboratory for Learning and Intelligent Systems, and he has been a Corresponding Member of the Austrian Academy of Sciences since 2013.
Thomas Müller is Professor of Theoretical Philosophy at the University of Konstanz, Germany. His academic career includes postdoctoral positions at Freiburg and Bonn and a faculty position at Utrecht, as well as visiting positions at Caltech and at Innsbruck. In his research he specializes in philosophy of agency, philosophy of science, logic, metaphysics, and philosophy of physics. Beyond his philosophical research, he has also worked in interdisciplinary contexts. Müller has been a Principal Investigator of projects funded by the Dutch Research Council, the European Research Council , the German National Science Foundation, and VolkswagenStiftung. He has been an elected member of the German National Academy of Sciences Leopoldina since 2020.
