They urged that reality is exhausted by nature, containing nothing “supernatural”, and that the scientific method should be used to investigate all areas of reality, including the “human spirit” (Krikorian 1944; Kim 2003).
So understood, “naturalism” is not a particularly informative term as applied to contemporary philosophers.
Thus many contemporary thinkers adopt a physicalist view of the mental realm because they think that otherwise we will be unable to explain how mental processes can causally influence our bodies and other physical items.
Similar considerations motivate ontologically naturalist views of the biological realm, the social realm, and so on.
Given that mental, biological and social phenomena do have such effects, it follows that they must satisfy the relevant restrictions.
Note how this kind of argument bites directly only on those categories that do have physical effects.
The term “naturalism” has no very precise meaning in contemporary philosophy.
Its current usage derives from debates in America in the first half of the last century.
So the first part of this entry, on ontological naturalism, will be concerned specifically with views about the general contents of reality that are motivated by philosophical argument and analysis.
And the second part, on methodological naturalism, will focus specifically on methodological debates that bear on philosophical practice, and in particular on the relationship between philosophy and science. Many ontological naturalists thus adopt a physicalist attitude to mental, biological and other such “special” subject matters.