"Whitehead is a radical empiricist in William James’ sense and a pragmatist in Charles Sanders Peirce’s sense. Radical empiricism does not mean that only measurable sense data counts. It means we refuse to truncate what is given in experience even when it overflows our favored abstractions. James thus includes not just bare sensa but relations, transitions, felt intensities, meanings, valuations, aesthetic patterns, habits, purposes, and the very act of knowing as ingredients of nature-as-experienced, rather than supernatural add-ons. Pragmatism does not mean “whatever works is true.” Still less does it mean whatever your colleagues will let you get away with saying, as the neo-pragmatist Richard Rorty once said. I am talking about OG pragmatism. It means that our most general ideas should not only be distilled from experience but should earn their keep by their consequences for further experience: by how well they coordinate inquiry, render our accounts of everyday life more coherent, and enable the fruitful expansion of practice, whether scientific, ethical, artistic, political, or spiritual.

In his first lecture at Harvard University in 1924, Whitehead argued that every special science operates with presuppositions about what counts as real, what counts as explanation, what counts as evidence, and what kinds of entities and relations are even eligible for consideration. These presuppositions are not delivered by physics as “results.” They are the conditions under which physics is intelligible in the first place.

Metaphysics is the search for the most general features of experiential reality (what other kind of reality is there?) presupposed not only by all the special sciences, but in ordinary life as well. Physics, chemistry, biology, psychology, sociology, law, art, ethics, religion, etc., each take up a region of experience and develop modes of thought adequate to that region. Metaphysics seeks what is common to them all, the generic categories that might allow us to coordinate all their conceptual specifications under one rationally coherent and empirically adequate scheme of thought.

This is why I find Walter’s supersessionist picture misguided. Science and metaphysics are not competing, so the former cannot replace the latter. Replacing superstition with peer review remains a valuable endeavor! But natural science cannot itself explain, to take one example, why it is that the nature of things should reward inductive reasoning. Whitehead’s diagnosis in Science and the Modern World is that modern scientific materialism, far from abolishing metaphysics, simply replaced an explicitly dualist metaphysics with an implicitly materialist one. Metaphysics thus went underground, dressed in drag as “physicalism,” and so became harder to criticize. Physics has for most of the last century chanted the “shut up and calculate” mantra, though more and more physicists are now realizing that it was only an unconscious materialistic metaphysics that made quantum weirdness seem so weird.

Of course, the new metaphysics must always remain in reciprocal exchange with the experimental sciences. This is a crucial point: metaphysics is not a “foundation” laid once and for all. But nor is it simply parasitic on scientific progress. Metaphysics and science exist in a negative feedback relation. When scientific advances destabilize its own inherited metaphysical categories (eg, quantum indeterminacy disrupting classical substance ontology), metaphysics must adjust them to restore conceptual coherence to our scientific understanding of the universe. Conversely, if metaphysical categories drift too far from empirical observation, scientific findings ought to constrain and force us to recalibrate them.

Scientific discoveries force revisions of our general categories. Revised general categories, in turn, can open new interpretive and experimental possibilities for the sciences. Metaphysics without science is empty. Science without metaphysics is blind. Without metaphysics to function as “the critic of abstractions” (Whitehead), natural science is all too prone to mistake the leading models of the day for the final ontology.

Science proceeds by abstraction. It selects, isolates, idealizes, quantifies, and formalizes. This is not a defect but its genius. But the genius has a cost. Abstraction always involves omission, and it invites the temptation to treat the abstract as the concrete.

The 17th-century picture of nature—simply located matter out there, private minds representing it in here—was a particularly successful abstraction. It was an astonishing engine of prediction and control. But by mistaking the abstraction for reality, modern societies have gone about applying the power of techno-science to actual nature in a way that has severely degraded the life systems of our planet. As if that were not bad enough, the correlate idea of isolated minds has totally deformed our image of the human being.

Whitehead’s “fallacy of misplaced concreteness” is perhaps his single most relevant concept for diagnosing the rhetoric of contemporary scientism. The fallacy involves taking mathematical models developed for certain purposes under certain idealizations and insisting that whatever does not fit inside them is unreal".

Segall