Brentano's Latter-day Monism

According to “existence monism,” there is only one concrete particular, the cosmos as a whole (Horgan and Potrč 2000, 2008). According to “priority monism,” there are many concrete particulars, but all are ontologically dependent upon the cosmos as a whole, which accordingly is the only fundamental concrete particular (Schaffer 2010a, 2010b). In essence, the difference between them is that existence monism does not recognize any parts of the cosmos, whereas priority monism does – it just insists that the parts are ontologically dependent upon the whole in this case. Brentano never maintained either of these views. But in the last two years of his life, he seems to have held the following approximation: there is only one physical substance, namely, the material universe as a whole. This is twice removed from existence or priority monism: first, it allows for a plurality of mental substances (souls); secondly, it allows for a plurality of physical accidents, which in Brentano’s reistic ontology are also concrete particulars. Still, the view that the only physical substance is the universe as a whole is quite radical and finds little precedent in the history of philosophy.