The methodological theme of CU is that to understand the nature and purpose of reality one must understand the Categories and their structural relations; analytic ontology is the proper route to a truly speculative cosmology.
If the sheet pleasure in reading the first half of CU comes in engaging its arguments, the importance and value of CU comes from seeing how genuinely powerful the methodological insight proves to be. One would be hard-pressed to locate a richer, deeper contemporary approach to the most fundamental questions of metaphysics. Part of its richness owes in no small measure to Monius’s helpfully locating the project of CU in a long tradition of Category commentary…
On the grammatical interpretation of Aristotle’s own contribution, the Categories provide a classification of significant words. On the onotological construal, the Categories provide a classification on beings. As expected, Monius aims to pursue the latter route, arguing that a conceptualist via media will (on one or another model of grasping a concept) revert to the grammatical or ontological approach. But Aristotle’s own Categories, even on the ontological approach, is severely limited in scope: as very like a list, it is hushed about the relations among the Categories, and altogether silent about whether such relations themselves might also be Categories. Moreover it says nothing about how the Categories relate to efficient and final causes, or to the structure of Forms described by Plato. Porphyry’s trees favored us with structure—ramifying downward beneath each of the Kinds to yield new categorical relations at each genus/differentia node; but this formal account was offered in the service of real definitions in logic—which Kant would only extend as the logical forms of judgment of a synthesizing mind. Hegel saw clearly that we must return to the idea that the Categories belong to a mind-independent reality. Synthesis was understood in terms of relations among universals, and thus arose a generative structure, the Dialectic of ever completing (with an opposite) what is, at respective loci in the realm of necessary universals, incomplete. But the Dialectical, opposite-completing (thesis/antithesis) structure of Hegel’s system offers no explicit analog to Porphyrian differentia for our downward descent, nor any trans-categorical structuring relations at common levels. Monius traverses all of these in an impressive synoptic discussion (18-24). As a short critical history alone it is worth the price of admission, particularly for those of us analytic philosophers who suffer varying degrees of historical myopia.