Levi Bryant asks at Critical Animal blog post on The Pluralism Wars: « Does ontological pluralism commit one to claiming spirits and demonic possession exist? » This is my answer:
1) The question is too general, asking about an abstraction « ontological pluralism » when there are many differing versions; In your discussions you shift between the college student who thinks all opinions are equal and Latour, who thinks that opinions have nothing to do with the constitution of different modes of existence. Mixing it all together can only create confusion, this is why I have chosen to talk about just one pluralist, Latour.
2) There is no necessity for all ontological pluralists to be committed to the existence of supernatural entities. In Latour’s case, he does believe in their existence, for empirical reasons, in the sense of his ontological investigation. Further, he concludes that we all believe in such things. This is not an anti-materialist point. For Latour all existence is anchored in material networks. It is however a non-reductionist point: material networks are constructed with qualitatively different relations, even though all relations are material too.
3) Latour thinks that these spirits are what is talked about in psychoanalysis. His objection to psychoanalysis is that its vocabulary is too narrow, and that it is systematically ontologically ambiguous. Noone knows the ontological status of the unconscious, so the explanation of spirits as unconscious complexes is the worst form of reductionism, explaining the unknown by the even more unknown. It is no help to add that the unconscious is material, there is no difference with Latour, who agrees on this point.
4) Latour would reformulate the above question in his own terms as
a) « Do psychogenic material networks exist? » His answer is obviously yes, the psyche is not pre-given, it is produced and constantly in production.
b) « Is the ontological status of the beings that transit these networks (emotions, affects, spirits, gods and demons) only referential, or is it also metamorphic? » Latour does believe that these entities can be studied by referential science, as for him everything can. But in the case of these beings, something very important would be missed if we stuck to just that mode of relation to them.