Heisenberg, Schroedinger and others launched a revolution in physics in 1925-6. Their matrix and wave mechanics were soon unified as quantum mechanics. Theories of quantum fields were developed within the same conceptual framework, until today quantum theory in its many forms provides a phenomenally successful foundation for much of physical science, with applications to other sciences including biology. But this empirical success has been achieved despite disagreement and lively debates among the active interdisciplinary group of scholars now probing the conceptual foundations of quantum theory itself. There has been notable progress in our understanding since the early discussions between intellectual giants like Einstein and Bohr. But there is still no consensus on how to answer puzzling basic questions about the meaning of central concepts of quantum theory such as measurement, probability, the nature of quantum states, locality and determinism. I'll begin by introducing quantum concepts as applied in some recent experiments, laying out the mathematics we'll need, and posing the main questions an interpretation of quantum theory needs to answer. Then we'll focus on two quite different current attempts to answer these questions: the Everettian approach (popularly known as the many worlds interpretation) and a Copenhagen-like approach I have recently been developing myself which I call a pragmatist interpretation. As you'll see, pursuing either of these approaches quickly leads to issues that are at least as philosophical as scientific in character. But the issues are quite different in each case. An Everettian must try to develop a concept of probability that applies when what appears to be a chance process has incompatible outcomes that all occur at once. This involves her in problems of decision theory, personal identity, and distributive justice. A pragmatist must say how claims about quantum states, quantum probabilities and quantum fields can be objectively true even though these are not physical things. And his dissolution of the notorious measurement problem commits him to a philosophically controversial inferentialist account of conceptual content.

January 9th Introduction: Aims and plan of course Required Reading: None

January 16th Superposition, vector states and the Born rule Required Reading: Scarani, chapters 1-3: Notes on quantum theory; Section 1

January 23rd Operators, Schrödinger Evolution and the Uncertainty Principle Required Reading: Notes on quantum theory; Sections 2, 3: Scarani, chapter 4

January 30th Mixed states, entanglement, and a famous argument Required Reading: Notes on quantum theory; Section 4: Einstein, Podolsky & Rosen "Can quantum-mechanical…complete?"

February 6th Contextuality, "non-locality" and "experimental metaphysics" Required Reading: Mermin, "The two theorems of John Bell": Scarani, Chapters 7, 8

February 13th The quantum measurement problem Required Reading: Wigner, "The problem of measurement": Wallace "Decoherence and its role in the modern measurement problem"

February 20th Everett and Ontology Required Reading: Saunders, "Many worlds? An introduction"; Wallace, "Decoherence and ontology"; Maudlin, "Can the world be only wave-function?" (all in Many Worlds?)

February 27th Everettian Probability I Required Reading: Saunders, "Chance in the Everett interpretation"; Papineau, "A fair deal for Everettians"; Wallace, "How to prove the Born rule"; (all in Many Worlds?)

March 6th Everettian Probability II Required Reading: Albert, "Probability in the Everett picture"; Greaves and Myrvold, "Everett and evidence" (both in Many Worlds?)

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March 20th Against Everett Required Reading: Kent, "One world versus many…"; Price, "Decisions, decisions…" (both in Many Worlds?)

March 27th A pragmatist view I. Healey "Quantum theory: A pragmatist approach".

April 3rd A pragmatist view II. Additional required Reading: Healey "How to use quantum theory locally to explain EPR-Bell correlations".

April 10th Quantum Explanation Required Reading: Healey "How quantum theory helps us explain"

April 17th Quantum Meaning Required Reading: Leggett, "Macroscopic realism…": "Healey "Quantum meaning": Brandom Articulating Reasons, chapter 1.

April 24th Students' Presentations

May 1st Students' Presentations

May 8th Final Papers Due