形而上自然主义，哲学学派之一，认为除了被自然科学研究的与我们所理解的物质世界相关的物、力、因以外凡是理论上不可能用自然科学去理解的东西都不存在。形而上自然主义认为所有与意识、心灵相关的概念都是指那些可被还原为、或依附于自然物、力、因的实体。而且，它否认任何超自然的物、力、因，比如诸种宗教中出现的事物、以及所有形式的目的论。它认为所有“超自然”的物均能由纯粹自然的原因来解释。它不只是对现有科学的反映，亦能展望科学在未来能够发现什幺。对于现实，形而上自然主义持一元论而不是二元论的态度。

Metaphysical naturalism, also called ontological naturalism, philosophical naturalism, and scientific materialism is a worldview which holds that there is nothing but natural elements, principles, and relations of the kind studied by the natural sciences, i.e., those required to understand our physical environment by mathematical modelling. In contrast, methodological naturalism is an assumption of naturalism as a methodology of science, for which metaphysical naturalism provides only one possible ontological foundation. Broadly, the corresponding theological perspective is religious naturalism or spiritual naturalism. More specifically, metaphysical naturalism rejects the supernatural concepts and explanations that are part of many religions.