Editing Directory:Logic Museum/Siger of Brabant/Quaestiones in Metaphysicam 20-21
Quaestiones in Metaphysicam 20-21
Introduction
The passages below are questions 20 and 21 of Siger of Brabant's questions on Aristotle's Metaphysics, concerning the problem of propositions with non-existent subjects. Although Siger is probably better known for his discussion of the question whether the proposition 'Man is an animal' is true if no individual men exist (not available in the Logic Museum), the passages here concern two related questions, namely whether (question 20) a thing named is necessarily what it is signified to be by the name (thus, is man necessarily a rational animal, given that 'man' means rational animal), and whether (question 21) a name signifies the same, and unequivocally, when the thing it signifies exists or not.
The questions are connected with one another, and divided the philosophers of the middle and late thirteenth century along party lines. Siger argued, as here, that when a name has a definition (such as 'rational animal', in the case of man), the definition is predicated necessarily of whatever has the name. Thus 'every man is an animal' is necessarily true because the definition of man is predicated of man.
Question 20 is whether, if a noun signifies 'X', it is necessary that anything denoted by the noun is X. Siger argues that what a name signifies is said necessarily of what is signified by the name. Therefore, if 'man' signifies a two-footed animal, he is necessarily a two-footed animal. Question 21 is whether a name signifies the same, and unequivocally, when the thing [it signifies] exists or not. Siger argues that a name has a 'single understanding' or single meaning, whether or not there is anything in reality that corresponds to the name. Another reason is that a name signifies one thing according, as it were, to its logical nature [ratio] [N1], and so there is always a single nature, there is a single signification. Therefore, although in reality there is not a single thing that we can predicate both being and non being, nevertheless in the name's logical nature there is one thing of which both can be predicated.
On the question of whether 'Man is an animal' is true if no individual men exist [N2] (not included here), Siger claimed that the hypothesis is absurd because in the Aristotelian perspective of nature the human species is eternal (Van Steenberghen 1977, pp. 265-9). Whereas Aristotle suggests that words signify concepts, Siger, it is objects that are the primary signification of words. Common terms signify the essence of things, rather than the other determinations that accompany a thing in real existence. The essence is the foundation of the signifying unity of the common term. A concept is thus the secondary object of the term, co-signified by it (cf Bazan 1980, Putallaz and Imbach 1997, p. 86).
We have no precise date for when the Quaestiones super libros metaphysicae was completed. It is unlikely to have been before 1265 (when Siger was only 25), nor after 1276, when Siger appeared on a charge of heresy, then fled to the papal court in Italy. It was probably completed in the early 1270's. (note to edit the omnis homo page accordingly)
