Workshop ‘Scientific Realism about the Quantum State’: Leeds, 9 September 2015

University of Leeds
Centre for the History and Philosophy of Science

This workshop examines recent debates about the nature of the quantum state (e.g. epistemic vs. ontic conceptions of the quantum state) in the broader context of scientific (anti-)realism.


Simon Friederich (Groningen)
Ruth Kastner (UMD)
Owen Maroney (Oxford)
Chris Timpson (Oxford)


9:30 Coffee and Welcome
9:45 – 11:15 Simon Friederich (Groningen): ‘Interpreting Quantum Theory: A Therapeutic Approach’
11:15 – 12:45 Chris Timpson (Oxford): ‘Realist and Anti-Realist Quantum Theory: The quantum state and explanation’


13:45 – 15:15 Ruth Kastner (University of Maryland): ‘Two misconceptions in the usual approaches to realism in quantum mechanics’


16:30 – 18:00 Owen Maroney (Oxford): Title TBA

18:00 – Pub and workshop dinner


Room G36, Baines Wing, School of PRHS, Woodhouse Lane, Leeds LS2 9JT
For directions see

There is no registration fee, but please contact Juha Saatsi ( by Friday 4th September if you plan to attend or have any questions about the event.

The workshop is part of the ARHC Scientific Realism and the Quantum Project


Ruth Kaster
(University of Maryland)

‘Two misconceptions in the usual approaches to realism in quantum mechanics’

This talk will identify two misconceptions hampering the discussion of realism in quantum theory. These are (1) the status of the measurement problem and (2) typical definitions of ‘real’. Concerning (1), it has become something of a dogma that there is no way to reconcile the unitary evolution of the wave function with the occurrence of single, determinate outcomes (apart from ad hoc additions or modifications to the theory, or an Everettian picture with known serious deficiencies). However, this predominant pessimistic view has been challenged; the challenge will be reviewed here. Concerning (2), common definitions of ‘real’ include metaphysical presumptions that can and should be dropped, just as previous metaphysical presumptions, such as absolute space and time, needed to be dropped in order for progress in physics to be made.

Simon Friederich

“Interpreting Quantum Theory: A Therapeutic Approach — a condensed account”

Can the epistemic conception of quantum states help to dissolve the main problems in the foundations of quantum theory? I give a tentatively positive answer to this question, based on a version of the epistemic conception that acknowledges the notion of a state assignment being performed correctly while rejecting the notion of a true quantum state of a quantum system. In addition, I argue by appeal to David Lewis’ Principal Principle that quantum theory is ‘locally causal’ inasmuch as quantum probabilities, properly construed, are independent of what occurs at space-like distance.

Chris Timpson
(University of Oxford)

“Realist and Anti-Realist Quantum Theory: The quantum state and explanation”

In discussing scientific realism and quantum theory, it is important first of all to distinguish between realism about quantum theory generically, and the more specific doctrine of realism about the quantum state in particular. The latter implies the former, but not vice versa. Arguably, one also needs to make more precise what would be meant by ‘quantum theory’ in the first place, before one can begin to talk about being realist (or otherwise) about it. Any realist approach to quantum theory of course then faces the two key problems: how it deals with the problem of measurement, and how it deals with EPR-Bell scenarios. A large part of the motivation towards anti-realism regarding quantum theory is then the oddity and apparent bad behaviour of the world described if one takes a realist approach. Yet the main difficulties for anti-realist approaches are the main strengths of realist positions: anti-realism about quantum theory seems to lead one towards a theory too denuded of descriptive content to underwrite the explanations that quantum theory in fact offers. In this talk I will review these matters, with a particular focus on the distinctive anti-realism (about the quantum state, and about the quantum formalism quite generally) of the quantum Bayesians, or QBists.

Owen Maroney
(University of Oxford)


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Filed under Conference announcements/CFPs, Quantum measurement, wuthrich

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