Aristotle defined Ontology as the science of being as such: unlike the special sciences, each of which investigates a class of beings and their determinations, Ontology regards “all the species of being qua being and the attributes which belong to it qua being” (Aristotle, Metaphysics, IV, 1). In this sense Ontology tries to answer to the question: What is being? or, in a meaningful reformulation: What are the features common to all beings?

This is what nowadays one would call General Ontology, in contrast with the various Special or Regional Ontologies (of the Biological, the Social, etc.). This distinction corresponds to the Husserlian one between Formal Ontology and Material Ontology [1]. But the Husserlian notion of “formal” does not involve only generality. For Husserl, the task of Formal Ontology is to determinate the conditions of the possibility of the object in general and the individuation of the requirements that every object’s constitution has to satisfy.

Recently, Nino Cocchiarella defined Formal Ontology as the systematic, formal, axiomatic development of the logic of all forms and modes of being [2]. [...] Cocchiarella’s definition is in our opinion particularly pregnant, as it takes into account both meanings of the adjective “formal”: on one side, this is synonymous of “rigorous”, while on the other side it means “related to the forms of being”. Therefore, what Formal Ontology is concerned in is not so much the bare existence of certain objects, but rather the rigorous description of their forms of being, i.e. their structural features. In practice, Formal Ontology can be intended as the theory of the distinctions, which can be applied independently of the state of the world, i.e. the distinctions: among the entities of the world (physical objects, events, regions, quantities of matter...); among the meta-level categories used to model the world (concept, property, quality, state, role, part...).