Philosophers Look at Quantum Mechanics pp 63-86 | Cite as

# The Reality of the Wavefunction: Old Arguments and New

## Abstract

The recent philosophy of Quantum Bayesianism, or QBism, represents an attempt to solve the traditional puzzles in the foundations of quantum theory by denying the objective reality of the quantum state. Einstein had hoped to remove the spectre of nonlocality in the theory by also assigning an epistemic status to the quantum state, but his version of this doctrine was recently proved to be inconsistent with the predictions of quantum mechanics. In this essay, I present plausibility arguments, old and new, for the reality of the quantum state, and expose what I think are weaknesses in QBism as a philosophy of science.

## Notes

### Acknowledgements

I thank the organisers of the XII International Ontology Congress for the kind invitation to contribute to these proceedings. I am also grateful to David Wallace for useful remarks, and to Rhys Borchert, James Read and particularly Christopher Fuchs and Christopher Timpson for invaluable critical comments on the first draft of this paper. None should be taken to endorse the arguments presented here.

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