Contemporary process metaphysics has achieved a number of important results, most significantly in accounting for emergence, a problem on which substance metaphysics has foundered since Plato. It also faces trenchant problems of its own, among them the related problems of boundaries and individuation. Historically, the quest for ontology may thus have been largely responsible for the persistence of substance metaphysics. But as Plato was well aware, an ontology of substantial things raises serious, perhaps insurmountable problems for any account of our (...) epistemic access to such things. Physical things are subject to change, and as such, they are poor objects of knowledge—if knowledge is to be more reliable than mere opinion. There is a reading of Plato’s Theaetetus on which knowledge may be understood as a relation between an epistemic subject and a logos, where logoi are intrinsically dialectical, and where dialectic is a kind of intersubjective activity. Insofar as this epistemology may be attributed to Plato, the project of this paper is Platonic in spirit. It is also, in a sense, Kantian, in that it divorces ontology from the search for things-in-themselves, redirecting our attention from things to objects: epistemic objects. Such objects can be understood, as Maurice Merleau-Ponty proposed, as shared by multiple subjects by virtue of their participation in an intersubjective world, constituted by what Shaun Gallagher calls participatory sense-making. On an epistemology constructed in this way, the fact that both epistemic objects and their subject are mutable is no obstacle to knowledge. Far-from-equilibrium systems are forever mutable; at thermodynamic equilibrium, there would be neither subject, nor object. Epistemic objects, on this picture, are metastable loci of interactive potential. (shrink)