Collin McMillan

1/ Recent moves by US colleges to bring back the SAT highlight a major tension: do “objective” metrics really reduce bias, or do “subjective” assessments (like “fit”) risk perpetuating class barriers? My research on class discrimination at elite firms sheds light. 🧵

What is Physicalism, and Why is it Almost Certainly True? Physicalism refers to the philosophical position that reality can be completely described by knowable mathematical laws. It is usually (but not necessarily) combined with reductionism: those laws are expressed in terms of the smallest constituents of matter. Support for this position includes both positive evidence (the extraordinary and unparalleled success of physicalist science) and negative evidence (the absence of any strong evidence against physicalism). Objections to physicalism are generally aesthetic: “I’m not reducible to mere atoms” etc. But even in principle, it’s hard to imagine an alternative to physicalism that would satisfy these critics. Assume we aren’t reducible to “mere atoms”, and some kind of ectoplasm steers human behavior. Then we could, in principle, make physical models of the human brain, observe actual humans, see where their behavior differs from the model, and then model these differences. By doing so, we would model ectoplasm. We might add “soul” as a fifth physical force, then produce differential equations that describe how it operates. At that point, it seems it would be another part of physics, not separate from physics. We would then see angry denunciations of soul science, insistence that we cannot be “mere ectoplasm”, etc. Reductionism is somewhat less logically certain than physicalism. It is logically possible that the laws of physics are piecewise: “obey Schrödinger’s equation until someone sacrifices a goat under a full moon, then grant their wish, then return to Schrödinger’s equation.” This seems both inelegant and hard to define (what exactly counts as a goat? What constitutes a full moon? Etc) but we may imagine such a thing could be consistently defined. The issue then would be the absence of evidence: show me your successful goat-sacrificing procedure and let’s try to replicate it. The scientific method, of which physicalism is an expression, is inescapable. No matter what arcane metaphysics you imagine, you either make testable claims or you don’t, and those claims either come true or they don’t. If they do, they will be called physics. For the elite nerds, it’s worth noting that physicalism does not imply materialism. It’s perfectly possible to be a physicalist idealist.