Spinoza's version of monism may have taken on some of the characteristics it had in that it was argued against the religious and pragmatic ideas of the Dutch intelligentsia, and not the animism it was thought was professed by the headhunters of the East Indies; the islands that constituted the economic basis of the civillisation in which Spinoza played a supporting role. According to Russell, Spinoza "is led to a pure and total pantheism". In truth Spinoza's philosophy is rather more restrained than "everything is everything"; it's a restricted monism. Spinoza would find nothing good or necessary in a child purposelessly dropping eggs from a roadbridge to smash on the motorway below; his philosophy can legitimately be called monism insofar as more extreme versions of monism lack literary adaptability.
Ray Brassier's thesis (pdf) puts forward some brilliant ideas about materialism (appropriately enough of "the type inaugurated by Parmenides"), followed up with a half-arsed injunction to adapt a version of monism to political economy. Nevertheless the real weakness of works like The Open Society and its Enemies, that improperly abstract two hostile parties out of the whole set of social relations, are such that Brassier's methodology would have some revelatory value.
The Open Society as Spinoza pastiche:
1. capitalism is a thing conceivable abstractly
2. given the supplementary axioms:
"the purposive nature of abstractions in pragmatic theorising"
and its corollary:
"the presumed perfection sui generis of the same"
(as per previous analyses)
a. capitalism is found to have a purpose
b. capitalism expresses this purpose perfectly
c. the directors of and ideologues for capitalism, as moments in the realisation of this purpose, perfectly express this purpose without constraint (2.b.), hence their real function aligns with their ostensible function. Since the function of the directors is to direct production it follows that this formal relationship expresses the real relationship.
3. capitalism since it has a purpose (2.a.) has as its purpose the reproduction of itself as capitalism
it follows that it also has as its purpose the non reproduction of itself as anything other than capitalism
4. capitalism and the open society are found to coexist. Since capitalism reproduces itself as itself etc (3.) capitalism reproduces and has as its purpose the reproduction of the open society.
5. Since capitalism has as its purpose not reproducing that which negates it (3.) and expresses this purpose perfectly (2.b.) such a workers movement as has as its purpose the negation of capitalism cannot itself be caused by capitalism.
6. such a workers movement in seeking to negate capitalism also seeks to negate the open society, which is purposely reproduced by capitalism (4.)