In The Rules of Sociological Method (The Free Press, 1982, pp. 35-36) Émile Durkheim writes:
The proposition which states that social facts must be treated as things…stirred up the most opposition. It was deemed paradoxical and scandalous for us to assimilate to the realities of the external world those of the social world. This was singularly to misunderstand the meaning and effect of this assimilation, the object of which was not to reduce the higher forms of being to the level of lower ones but…to claim for the former a degree of reality at least equal to that which everyone accords to the latter….we do not say that social facts are material things, but that they are things just as are material things, although in a different way.
What indeed is a thing? The thing stands in opposition to the idea….A thing is any object of knowledge which is not naturally penetrable by the understanding….It is all that which the mind cannot understand without going outside itself, proceeding progressively by way of observation and experimentation from those features which are the most external and the most immediately accessible to those which ‘are the least visible and the most profound. To treat facts of a certain order as things is therefore not to place them in this or that category of reality; it is to observe towards them a certain attitude of mind. It is to embark upon the study of them by adopting the principle that one is entirely ignorant of what they are, that their characteristic properties, like the unknown causes upon which they depend, cannot be discovered by even the most careful form of introspection.
This passage of Durkheim’s is rich in metaphysical import–precisely because it offers a definition of ‘thing’ and suggests existence can be ascribed to orders of being that are not ‘material,’ and which are not for that reason, lacking in ‘reality.’ The fundamental opposition for Durkheim is between objects of the intellect–‘ideas’–and those that are not–things, which require externally directed study. These ‘things’ can be ‘material,’ made up of material substance, or they can have some unknown constitution. But a ‘thing’s’ reality is not a matter of its composition, or its location in space and time; rather, it is a matter of what relation our thought bears to it. The opposition between the ‘material’ and the ‘immaterial’ is not one between ‘existence’ and ‘non-existence’; the immaterial can have just as much reality as the material. Rather, if the ‘thing’ in question is an object of a particular kind of study, if it is a component of our theoretical schemes, it has reality. The notion of ‘reality’ coming in ‘degrees’ might remain obscure, but whatever it is, Durkheim suggests that the lack of materiality of social facts does not prevent them from being ‘things’ if our methods of study for them–non-introspective, directed outward–treat them as such. In this blend of metaphysics and epistemology Durkheim’s claims reveal a certain pragmatist sensibility at the heart of the social science whose foundations he was establishing; here, yet again, Durkheim shows that methodology is metaphysics.