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Extending the Agent in QBism

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Abstract

According to the subjective Bayesian interpretation of quantum mechanics (QBism), the instruments used to measure quantum systems are to be regarded as an extension of the senses of the agent who is using them, and quantum states describe the agent’s expectations for what they will experience through these extended senses. How can QBism then account for the fact that (i) instruments must be calibrated before they can be used to ‘sense’ anything; (ii) some instruments are more precise than others; (iii) more precise instruments can lead to discovery of new systems? Furthermore, is the agent ‘incoherent’ if they prefer to use a less precise instrument? Here we provide answers to these questions.

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Notes

  1. The word ‘sense’ may need qualification here, since the nature of the experience still bears the indelible mark of the equipment through which the atoms are ‘sensed’. For this kind of sensing-through-equipment we might borrow the word Umsicht from Heidegger.

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Acknowledgements

I thank R. Schack, J. DeBrota, B. Stacey and C.A. Fuchs for valuable discussions. This work is based on ideas first presented at the QIRIF conference in Växjö, Sweden (2019), and further developed based on discussions with the attendees of the Phenomenological Approaches to Physics conference at Stony Brook University, NY (2019). I am indebted to the organizers of both conferences. This work was supported in part by the John E. Fetzer Memorial Trust.

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  1. QBism group, University of Massachusetts Boston, 100 Morrissey Boulevard, Boston, MA, 02125, USA

    Jacques Pienaar

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Correspondence to Jacques Pienaar.

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Pienaar, J. Extending the Agent in QBism. Found Phys 50, 1894–1920 (2020). https://doi.org/10.1007/s10701-020-00375-z

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