During the academic years 1972-1973 and 1973-1974, an intensive sem inar on the foundations of quantum mechanics met at Stanford on a regular basis. The extensive exploration of ideas in the seminar led to the org~ization of a double issue of Synthese concerned with the foundations of quantum mechanics, especially with the role of logic and probability in quantum meChanics. About half of the articles in the volume grew out of this seminar. The remaining articles have been so licited explicitly from individuals who are actively working in the foun dations of quantum mechanics. Seventeen of the twenty-one articles appeared in Volume 29 of Syn these. Four additional articles and a bibliography on -the history and philosophy of quantum mechanics have been added to the present volume. In particular, the articles by Bub, Demopoulos, and Lande, as well as the second article by Zanotti and myself, appear for the first time in the present volume. In preparing the articles for publication I am much indebted to Mrs. Lillian O'Toole, Mrs. Dianne Kanerva, and Mrs. Marguerite Shaw, for their extensive assistance.

This volume provides a broad perspective on the state of the art in the philosophy and conceptual foundations of quantum mechanics. Its essays take their starting point in the work and influence of Itamar Pitowsky, who has greatly influenced our understanding of what is characteristically non-classical about quantum probabilities and quantum logic, and this serves as a vantage point from which they reflect on key ongoing debates in the field. Readers will find a definitive and multi-faceted description of the major open questions in the foundations of quantum mechanics today, including: Is quantum mechanics a new theory of (contextual) probability? Should the quantum state be interpreted objectively or subjectively? How should probability be understood in the Everett interpretation of quantum mechanics? What are the limits of the physical implementation of computation? The impact of this volume goes beyond the exposition of Pitowsky’s influence: it provides a unique collection of essays by leading thinkers containing profound reflections on the field. Chapter 1. Classical logic, classical probability, and quantum mechanics (Samson Abramsky) Chapter 2. Why Scientific Realists Should Reject the Second Dogma of Quantum Mechanic (Valia Allori) Chapter 3. Unscrambling Subjective and Epistemic Probabilities (Guido Bacciagaluppi) Chapter 4. Wigner’s Friend as a Rational Agent (Veronika Baumann, Časlav Brukner) Chapter 5. Pitowsky's Epistemic Interpretation of Quantum Mechanics and the PBR Theorem (Yemima Ben-Menahem) Chapter 6. On the Mathematical Constitution and Explanation of Physical Facts (Joseph Berkovitz) Chapter 7. Everettian probabilities, the Deutsch-Wallace theorem and the Principal Principle (Harvey R. Brown, Gal Ben Porath) Chapter 8. ‘Two Dogmas’ Redu (Jeffrey Bub) Chapter 9. Physical Computability Theses (B. Jack Copeland, Oron Shagrir) Chapter 10. Agents in Healey’s Pragmatist Quantum Theory: A Comparison with Pitowsky’s Approach to Quantum Mechanics (Mauro Dorato) Chapter 11. Quantum Mechanics As a Theory of Observables and States and, Thereby, As a Theory of Probability (John Earman, Laura Ruetsche) Chapter 12. The Measurement Problem and two Dogmas about Quantum Mechanic (Laura Felline) Chapter 13. There Is More Than One Way to Skin a Cat: Quantum Information Principles In a Finite World(Amit Hagar) Chapter 14. Is Quantum Mechanics a New Theory of Probability? (Richard Healey) Chapter 15. Quantum Mechanics as a Theory of Probability (Meir Hemmo, Orly Shenker) Chapter 16. On the Three Types of Bell's Inequalities (Gábor Hofer-Szabó) Chapter 17. On the Descriptive Power of Probability Logic (Ehud Hrushovski) Chapter 18. The Argument against Quantum Computers (Gil Kalai) Chapter 19. Why a Relativistic Quantum Mechanical World Must be Indeterministic (Avi Levy, Meir Hemmo) Chapter 20. Subjectivists about Quantum Probabilities Should be Realists about Quantum States (Wayne C. Myrvold) Chapter 21. The Relativistic Einstein-Podolsky-Rosen Argument (Michael Redhead) Chapter 22. What price statistical independence? How Einstein missed the photon.(Simon Saunders) Chapter 23. How (Maximally) Contextual is Quantum Mechanics? (Andrew W. Simmons) Chapter 24. Roots and (Re)Sources of Value (In)Definiteness Versus Contextuality (Karl Svozil) Chapter 25: Schrödinger’s Reaction to the EPR Paper (Jos Uffink) Chapter 26. Derivations of the Born Rule (Lev Vaidman) Chapter 27. Dynamical States and the Conventionality of (Non-) Classicality (Alexander Wilce).

This volume examines the logic, theory and mathematics of quantum mechanics in a clear and thorough way.

The last few years have been characterized by a tremendous development of quantum information and probability and their applications, including quantum computing, quantum cryptography, and quantum random generators. In spite of the successful development of quantum technology, its foundational basis is still not concrete and contains a few sandy and shaky slices. Quantum random generators are one of the most promising outputs of the recent quantum information revolution. Therefore, it is very important to reconsider the foundational basis of this project, starting with the notion of irreducible quantum randomness. Quantum probabilities present a powerful tool to model uncertainty. Interpretations of quantum probability and foundational meaning of its basic tools, starting with the Born rule, are among the topics which will be covered by this issue. Recently, quantum probability has started to play an important role in a few areas of research outside quantum physics—in particular, quantum probabilistic treatment of problems of theory of decision making under uncertainty. Such studies are also among the topics of this issue.

Quantum probability is a subtle blend of quantum mechanics and classical probability theory. Its important ideas can be traced to the pioneering work of Richard Feynman in his path integral formalism.Only recently have the concept and ideas of quantum probability been presented in a rigorous axiomatic framework, and this book provides a coherent and comprehensive exposition of this approach. It gives a unified treatment of operational statistics, generalized measure theory and the path integral formalism that can only be found in scattered research articles.The first two chapters survey the necessary background in quantum mechanics and probability theory and therefore the book is fairly self-contained, assuming only an elementary knowledge of linear operators in Hilbert space.

This work has grown out of the lecture notes that were prepared for a series of seminars on some selected topics in quantum logic. The seminars were delivered during the first semester of the 1993/1994 academic year in the Unit for Foundations of Science of the Department of History and Foundations of Mathematics and Science, Faculty of Physics, Utrecht University, The Netherlands, while I was staying in that Unit on a European Community Research Grant, and in the Center for Philosophy of Science, University of Pittsburgh, U. S. A. , where I was staying during the 1994/1995 academic year as a Visiting Fellow on a Fulbright Research Grant, and where I also was supported by the Istvan Szechenyi Scholarship Foundation. The financial support provided by these foundations, by the Center for Philosophy of Science and by the European Community is greatly acknowledged, and I wish to thank D. Dieks, the professor of the Foundations Group in Utrecht and G. Massey, the director of the Center for Philosophy of Science in Pittsburgh for making my stay at the respective institutions possible. I also wish to thank both the members of the Foundations Group in Utrecht, especially D. Dieks, C. Lutz, F. Muller, J. Uffink and P. Vermaas and the participants in the seminars at the Center for Philosophy of Science in Pittsburgh, especially N. Belnap, J. Earman, A. Janis, J. Norton, and J.

This book deals with two main topics. The first is a theory that aims to unify the many interpretations of probability presented in the literature. The second uses this comprehensive theory of probability to answer the questions of quantum mechanics that have long been debated. The entire book proposes original solutions that several experimental cases substantiate.