The first decades of the thirteenth century are characterized by logical texts (several of which are edited in De Rijk 1962/1967) still presenting supposition theory in its early stages. Its first reasonably mature versions, where it acquires the more or less standard shape it was to retain for many centuries, are to be found in the writings of the thirteenth-century terminists, also known as ‘‘summulists’’ because they produced complete overviews of logic (summa, ‘‘sum’’ or summula, ‘‘little sum’’) where the properties of terms, and supposition in particular, occupy a key position. The main authors of this generation are William of Sherwood, Peter of Spain, Roger Bacon, and Lambert of Auxerre/Lagny, each of them having written at least one comprehensive logical text.
Moreover, the thirteenth century is also the period when the Oxford/Paris opposition becomes significant. In effect, while in the twelfth century the development of supposition theory is restricted to the Parisian schools, the thirteenth century witnesses the emergence of a distinctively Oxford school in logic, and concerning supposition in particular, even though there were many points of mutual influence between the two centers (see De Libera 1982). One distinctive characteristic of the Parisian tradition is the importance of natural supposition, which is usually construed as the non-contextual, stable supposition of a term (resembling thus the notion of signification), as opposed to accident supposition, i. e., the supposition that a term actually acquires in a given propositional context (such as in Peter of Spain and
Lambert of Auxerre/Lagny). Indeed, natural supposition is the only variation in the development of this concept that concerns terms out of a propositional context.
The four authors just mentioned each offer a particular version of supposition theory, each with its own divisions and subdivisions (for trees representing these divisions per author, see Spade 1996:272-276). In fact, the different versions of the theory recognize different divisions and subdivisions of supposition, but they mostly agree on the definitions of the kinds of supposition that they do recognize. For the present purposes, let us examine the divisions and subdivisions presented by William of Sherwood in his Introduction to Logic, as his theory contains all the kinds and modes of supposition that remained influential throughout the fourteenth century and beyond.
Sherwood’s first division of proper supposition is between formal and material supposition. He defines formal supposition as ‘‘when a word supposits what it signifies” (William of Sherwood 1966:107), as signification is inherently related to forms: for Sherwood, the signification of a common term is the universal form it corresponds to, e. g., humanity in the case of ‘‘man.’’ But formal supposition is of two kinds: simple supposition is when a term supposits ‘‘for the signified form’’; personal supposition is when a term supposits ‘‘for a thing bearing the form’’ (Sherwood 1966:107), that is, for the individuals instantiating the universal nature. Indeed, these are the definitions of personal and simple supposition that one generally encounters in writings of the thirteenth and fourteenth centuries (with an important modification regarding simple supposition brought about by Ockham, as we shall see). Material supposition is opposed to formal supposition in that it is not significative; indeed, Sherwood continues the tradition of referring to autonymic uses of a word (i. e., standing for itself) as ‘‘material,’’ as in the notion of materiale impositum discussed above.
These three main kinds of proper supposition - personal, simple, and material - are in effect to be found in most fourteenth-century texts (except for those following Buridan in his dismissal of simple supposition), and account for the variation of ontological kinds of supposita (variation (2) above). Interestingly, none of the other thirteenth-century main texts has either formal or material supposition as kinds of supposition, but they all have personal and simple supposition: for Roger Bacon and Lambert of Auxerre, what Sherwood understood as material supposition, namely, the supposition of a term for itself or for other expressions qua expressions, becomes a variation of simple supposition. But formal supposition and especially material supposition make a resounding comeback in the fourteenth century.
Another division of formal supposition presented by Sherwood is between common and discrete supposition. It is unclear whether Sherwood intends it to be a subdivision of the simple-personal division or the other way round - or perhaps as an independent division altogether. Either way, the subsequent tradition usually treats this distinction as a subdivision of personal supposition: common supposition is the supposition of common terms, i. e., of terms not meant to designate one specific individual, while discrete supposition is the supposition of singular terms such as proper names and demonstrative pronouns, which pick out one specific individual.
For Sherwood, personal common supposition is further subdivided into determinate and confused supposition; confused supposition is then divided into merely confused, and confused and distributive; and finally, the latter is divided into mobile and immobile. The divisions of the modes of personal common supposition are then to be found in virtually all subsequent texts (although the mobile vs. immobile distinction tends to disappear), and account for the different quantities of supposita that are required for the verification of different propositional contexts (variation (4) above, treated elsewhere in this volume.)
As for variation (3) above, it is usually accounted for by means of the concepts of ampliation and restriction, as in William of Sherwood, Peter of Spain, and Lambert of Auxerre/Lagny; Sherwood also discusses this kind of variation within the context of his theory of composite and divided senses of modal propositions. The idea is that some propositional contexts ampliate the range of supposita being supposited for by a term, for example in a modal sentence such as ‘‘A man can be white’’; in this case, the supposition of ‘‘man’’ is not limited to the presently existing men, but also to possible men. A similar phenomenon occurs with tensed propositions. Other contexts restrict the range of supposition, for example, when an adjective modifies a noun, such as ‘‘white man.’’ But ampliation and restriction usually do not generate subkinds of supposition, rather it is usually said that the supposition of a given term is ampliated or restricted.
In the last decades of the thirteenth century, there was a marked decline of the influence of terminist logic, in particular in Paris, where an alternative approach to semantics became very influential, that of the modistae (Ebbesen 1981, 1985). The modistae influence in Oxford was less intense, but still felt. In any case, terminism did not go into total dormant state in this period, as is
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Sometimes thought: Roger Bacon’s De signis, where a sophisticated version of supposition theory is presented (improving his own earlier theory presented in his Summulae dialectices) was written in the last decades of the thirteenth century, in Oxford (see De Libera 1982).
World History
