Abstract
ACCORDING TO DUNS SCOTUS, what makes a material substance an individual is a positive entity which falls within the category of substance and contracts the specific nature to this or that. That entity, called haecceitas, together with the formal distinction, constitutes the core of Scotus' theory of individuation. But what is haecceitas? Haecceitas is not definable. Nor can we be acquainted with it. Then how could we understand it? Both negatively and positively, Scotus himself tried to give an answer to this question. Before presenting his haecceitas theory, Scotus criticized six different types of rival theories available in his day: the position of the nominalists, the double negation theory, the theory of individuation by actual existence, the theory of individuation by quantity or other accidents, the theory of individuation by matter, and the theory attributed to Godfrey of Fontaines. In other words, he was explaining "what haecceitas is not" when he criticized these theories. More importantly, he tried to give us a positive characterization of haecceitas. Since he used "individual difference" as a synonym for "haecceitas," he resorted to an analogy between the specific difference and the individual difference in order to explain the notion of haecceitas. The problem is that twentieth-century ontologists may not be patient enough to study the triple analogy, which again presupposes Scotus' doctrines of the formal distinction and the ultimate difference. In order to draw their attention to Scotus' theory of individuation, one would need to discuss the following questions: How can we translate the term "haecceitas" into modern terminology? Is there any counterpart of haecceitas in contemporary ontology? For what reasons should we reintroduce haecceitas into the current discussion of individuation, if it has a good counterpart? Is there still anything significant left to add to our understanding of haecceitas?