The problem of universals is one of the main philosophical issues. In this book the author reconstructs the history of the problem from Boethius to John of Salisbury, considering a selection of medieval representative texts.

This study is concerned with the ontology of Gilbert of Poitiers. Gilbert takes the cue from Boethius’ Theological writings, which contain a system of categorical organization different from the one found in the logical commentaries. Gilbert’s ontological catalog is quite varied: there are special, general and differential subsistences which are called by name: ‘humanity’, ‘animality’, ‘rationality’. We then have all the qualitative and quantitative determinations which rely on subsistences; these properties have particular instantiations, but at the same time eternal specimens. (...) In parallel Gilbert describes a world of individual substances and properties related by certain relations of similarity. There are other objects which Gilbert speaks little about and not always in univocal way, as collections of individual properties and undifferentiated objects, for instance the raw material and the first elements. This rich ontology can be used to support different metaphysical games, my suggestion is that Gilbert does not definitely decide to choose one, whilst providing interesting possible strategies for some of them. (shrink)

In the commentaries on Porphyry Boethius on the one hand explains the properties of predication relation at abstract level, from another hand he supplies some ontological options about what can instantiate the terms of the relation, at the end he seems to prefer the similarities as objects of abstract thought. Other options are anyway present, in the commentary on Categories and in the Theological Treatises. One cannot say that the catalogues are complementary or that the same things are catalogued once (...) only, under the same label. On the contrary, objects such as forms, essences and material components can be considered from points of view that are different and not easily comparable. In the present article I will deal with Boethius’ ontological approach not strictly concerned with the Porphyrian text and riddle. (shrink)