In the fourteenth century, terminist logic somehow reemerges as the chief doctrine for semantic analysis, completely replacing the modistae theories. In the very first years of the century, at Oxford, Walter Burley writes a De suppositionibus treatise, essentially taking over Sherwood’s distinctions of supposition. At the same time, Burley seems to have been the first to introduce quite a few innovations, which were to remain influential in the fourteenth century and beyond (see Brown 1972). Thus, one can say that Burley’s treatise inaugurates fourteenth-century-style supposition theory.
The next important text in the development of supposition theory was composed in the 1320s by William of Ockham, also an Englishman: his Summa logicae. Ockham’s Summa is revolutionary for many different reasons, among which his purely extensional definition of signification - for Ockham, a common term such as ‘‘man’’ signifies each and every man, not the universal humanity. Another important innovation developed by Ockham (but with earlier signs in the thirteenth century, for example, in Lambert of Auxerre/Lagny; see Read 2006: sect. 3) is the idea that the concept itself is a sign, just as written and spoken terms. In fact, Ockham develops the idea of a mental language functioning very much like written and spoken language, and thus equally apt to undergo semantic analysis; indeed, Ockham applies the supposition apparatus also to mental propositions (see Panaccio 1999), but with some paradoxical results (see Spade 1980).
While Ockham was clearly inspired by Burley’s treatise (the section on the supposition of relatives is almost an exact copy of the same section in Burley’s treatise see Brown 1972), he had to adjust the supposition machinery to the ontological and semantic modifications he had introduced. Thus, for Ockham simple supposition is no longer the supposition for an extra-mental universal, as such things simply do not exist in his ontology. Rather, he reformulates simple supposition as the supposition for the mental term corresponding to the spoken or written term in question. Similarly, personal supposition becomes the supposition for the thing(s) that the term signifies, given his reformulation of the notion of signification (Summa logicae I, chap. 64). For the rest, in particular with respect to the subdivisions of the modes of personal supposition, Ockham maintains the traditional divisions.
After Ockham, one important tradition in the fourteenth century (following Buridan) simply dispenses with simple supposition altogether, maintaining only personal and material as the main kinds ofproper supposition. The idea is this: if simple supposition is the supposition for a mental term, as Ockham has it, then it is in fact a kind of material supposition (Buridan, Summulae de dialectica 4.3.2). Like Ockham, Buridan rejects the existence of extra-mental universals, so for him simple supposition becomes a superfluous concept.
Another author writing in the Buridanian tradition, Marsilius of Inghen, introduces another important innovation, namely that of applying the subdivisions traditionally reserved to personal supposition to material supposition as well (see Marsilius of Inghen 1983 And Dutilh Novaes 2008a:sect. 2). With this move, it becomes possible to ‘‘quantify’’ over occurrences ofspoken, written, and mental terms being the material supposita of terms, just as one quantifies over the extra-mental individuals that are typically (but not always) the personal supposita of terms.
All in all, in the fourteenth century supposition theory is widely applied to a variety of topics; in fact, it becomes an over-arching methodological tool. Ockham, for example, makes extensive use of it for theological as well as physical analyses. In effect, a significant application of supposition theory in the fourteenth century is to the issues surrounding the dogma of the Trinity (see the entry on Trinitarian Logic in this volume). Moreover, the theory continues to develop well into the fifteenth and sixteenth century. (The interested reader is urged to consult the secondary literature on these developments, in particular the work of E. J. Ashworth.)
World History
