Material reality exists independent of human measurement

(Andrew W., PoliSci@Madison, Our place in the universe: Alexander Wendt and

quantum mechanics International Theory (2022), 14 (1), 130–145 doi:10.1017/S1752971921000063)

Before we leave Part I, however, I should articulate my first substantial objection to the direction Wendt is going. By claiming that quantum mechanics undermines materialism, mechanism and the distinction between observer and observed, Wendt is giving a quantum gloss to an old tradition of thought, going back to George Berkeley8 and before, which denies the existence of the external, material world. Berkeley argued that since all we have access to is our mental impressions, they must be all that really exist. The quantum spin on this is to say that since particles don’t really exist until we measure them, our measuring is what brings them into existence. However, this kind of quantum Berkeleyism is as unpersuasive as the original classical version. Two objections can be raised, one classical and one quantum. The classical objection to Berkeley remains as forceful as ever. Nothing in our sensory impressions makes the slightest degree of sense unless we presuppose a material world that exists independent of our minds. And once we do, lots of things make a great deal of sense. The entire edifice of everyday life, not to mention all of science, depends on this assumption. The objection to the quantum version is that it is not ‘measurement’ per se that collapses wave functions, but their impact on physical objects. A photon wave function that is emitted by the sun and hits a leaf in the Amazon rain forest where no one is there to see is absorbed and may even contribute to photosynthesis and help the tree grow. The fact that no one measured it doesn’t mean it didn’t happen. Other photons hit the moon, and warm it up slightly without anyone noticing. Almost every photon in the history and future of the universe will be born, travel, and die unmeasured. We affect a tiny fragment of reality by measuring it, but the vast bulk of reality rolls on without us. The fact that our measurements affect the world makes it harder for us to learn about it, but it remains out there all the same. In the end, Wendt is not a full-blown quantum Berkeley; he takes the argument in a slightly different direction. But he uses some of these arguments to undermine our usual faith in objective reality, so it is important to critique them before moving on.