Physicalism, the belief that everything in the universe must be physical, is a form of scientism

Physicalism is a metaphysical position asserting that everything that exists is physical or depends on the physical, with no non-physical substances or properties.plato.stanford.eduplato.stanford.eduPhysicalism (Stanford Encyclopedia of Philosophy)en.wikipedia.orgen.wikipedia.orgPhysicalism It is primarily a claim about the nature of reality. Scientism, on the other hand, is often defined as the view that the methods of natural science are the only or best way to understand all phenomena, including social and mental phenomena.encyclopedia.comencyclopedia.comScientism While some forms of scientism may adopt a reductionist stance similar to physicalism, physicalism itself does not necessarily entail scientism. Philosophers distinguish between physicalism as a metaphysical thesis and scientism as an epistemological or methodological stance. Physicalism can be held without endorsing scientism’s stronger claims about the exclusivity of scientific methods. Moreover, some critiques emphasize that physicalism does not automatically reduce all phenomena to scientific explanations or deny other forms of knowledge.philarchive.orgphilarchive.orgPhysicalism, Not Scientism Therefore, labeling physicalism simply as a form of scientism conflates a metaphysical worldview with an epistemological doctrine, which is misleading.

In summary, while there is overlap in that both physicalism and scientism value the physical sciences highly, they are not identical positions. Physicalism concerns what exists; scientism concerns how we know or explain what exists.