I’m an admirer of the relational interpretation of quantum mechanics (RQM), due originally to Carlo Rovelli. The revised SEP entry on RQM by Federico Laudisa and Rovelli made reference to two new papers about RQM by philosophers of science Bas C. Van Fraasen and Michel Bitbol. Unfortunately, Van Fraasen’s paper is not yet published, and Bitbol’s paper (entitled “Physical Relations or Functional Relations?”) is in French. However, in the course of looking for this, I found another interesting paper by Bitbol in English, which was published in a journal called NeuroQuantology: “Consciousness, Situations, and the Measurement Problem of Quantum Mechanics.”
In this paper, Bitbol looks at the history of discussions about the putative role of consciousness in the measurement process. He concludes that it is a mistake to think that human minds need have anything special to do with the measurement process; but a careful analysis reveals that QM does necessitate at a minimum taking into account particular viewpoints. His analysis places Bitbol in the same general camp as RQM and also the “Perspectivist” interpretation I described in these posts which referenced Paul Merriam’s papers.
The bulk of Bitbol’s paper is his careful presentation of a thought experiment which shows the difference between classical and quantum physics as it relates to the role of the observer in a measurement. (This exposition is similar to the thought experiment known as “Wigner’s friend” -- see Henry Stapp's discussion in this doc file). Wave functions characterize the observables of a system relative to interaction with another particular system –- in fact we can characterize a whole chain of interactions via a wave function -- until the chain comes to the end with our observation. But, Bitbol says the following:
"I am not saying that WE are unique or privileged beings in nature (this would be collective solipsism of an absurd sort), but only that we are privileged beings for US! As soon as we establish a relation with an element of the measurement chain, this element acquires a determination relative to US. Nothing has thus to be changed in the physical description, since determinations of the measurement chain are still relative to something. But everything is different for US, since the determinations of the measurement chain are now relative to US. And a relation of which WE are one term is something quite peculiar, even if it is only peculiar…from OUR point of view."
As he says, in classical physics, the fact that we are situated subjects with a point of view can be “bracketed”, and we can view ourselves as just another object. In quantum mechanics, this “situatedness” is irreducible. This doesn’t mean we can’t naturalize ourselves in picturing the world - we don’t need to think human consciousness is something distinct from the rest of nature. But QM teaches us that this process of naturalization has a boundary – points of view cannot be reduced or eliminated from the picture.