Which philosophy asserts that only physical substances exist?

Materialism is a philosophical viewpoint that posits that physical substances are the only things that exist. This belief holds that everything in the universe, including thoughts, consciousness, and emotions, arises from physical interactions and material processes. According to materialism, reality is fundamentally composed of matter, and any phenomena that appear to be non-physical can ultimately be explained through physical laws and scientific understanding.

In contrast, moderate vitalism acknowledges the role of life forces beyond mere physical matter, suggesting that living things have properties that aren’t entirely reducible to their physical components. Autopoiesis refers to systems capable of self-maintenance and self-renewal but doesn't reject the existence of other non-physical concepts. Idealism posits that reality is primarily mental or spiritual in nature, asserting that ideas or consciousness constitute the essence of existence, contrary to the materialist view. Thus, materialism stands out as the philosophy that strictly maintains the existence of only physical substances.