This paper is an attempt at exploring, and criticizing, the underlying ontology of the neoclassical economics, in the context of the general equilibrium theory, to be taken as the methodological "hard core" of this program. The reason for such an attempt is the conviction that the controversies over the "correct" methodology of mainstream economics, concentrating mainly on epistemological issues and accepting a form of "empirical realism," function to justify actual practices of economists themselves, rather than being prescriptive with respect to the correct "scientific" methodology. Such a defensive strategy however, creates in general a lacunae in the debates over methodological issues of economics. Based upon this conviction, it is argued in the paper that the adopted ontology of neoclassical economics, being an ontology of particulars implying methodological individualism, is the main problematic aspect of the whole approach, for it causes the analysis to fail to achieve what it promises to achieve: the explanation of the operation of the market system.