What does naturalism assert regarding reality?

Naturalism is a philosophical viewpoint that asserts that everything that exists can be explained in terms of natural causes and laws. This perspective emphasizes that reality is strictly limited to the observable universe and that anything that cannot be measured, observed, or scientifically validated is not considered part of reality. Therefore, the assertion that only things that can be measured scientifically are real aligns perfectly with the principles of naturalism. This belief often dismisses supernatural explanations and focuses on empirical evidence as the foundation for understanding the world around us.

In contrast, the other options present ideas that do not align with naturalism. The notion that only the spiritual is real suggests a belief system that acknowledges non-empirical elements, which naturalism explicitly denies. The idea of reality being subjective implies that individual perceptions define reality, which contradicts the objective nature of naturalist philosophy. Lastly, claiming that all experiences are valid does not fit within a naturalistic framework, as this perspective would require critical scrutiny of experiences through an empirical lens, thereby ensuring that only those experiences that can be substantiated by scientific inquiry are accepted as real.