I CANNOT TELL A LIE: HUGH OF LAWTON'S CRITIQUE OF WILLIAM OF OCKHAM ON MENTAL LANGUAGE The idea that at least some mental activity constitutes a mental language entered the medieval tradition from two ofthe most authoritative of sources: Aristotle and Augustine.1 The concept of mental language had a long history prior to the fourteenth century.2 But with William of Ockham, the history of the concept took a decided turn. Ockham devoted such systematic attention to the idea ofmental language , putting it to new uses, that discussion and controversy erupted among his successors. Discussions of mental language centered around four questions: 1). Does mental language exist? 2). Ifso, what is it like? 3). What is its relation to spoken and written language? and 4). Does postulation ofmental language do any useful philosophical work? Ockham gave a much more detailed answer to the second question than had his predecessors, changed the usual Aristotelian answer to the third question, which not only subordinated spoken language to mental, an idea Ockham maintained, but also proposed that spoken language ' Aristotle, De lnterpretatione 1.16a3—18, and see Norman Kretzman, "Aristotle on Spoken Sound Significant by Convention," in Ancient Logic and Its Modem Interpretations, ed. John Corcoran, Buffalo Symposium on Modernist Interpretations ofAncient Logic, 21 and 22 April, 1972 (DordrechtHolland : D. Reidel, 1974) 3-21. For Augustine, Sermo 288 (PL XXXVIII, 1304-6), and De Trinitate, lib. 15, cap. 10, n. 19 (CCL L, 486), are the key texts. See Gabriel Nuchelmans, Theories of the Proposition: Ancient and Medieval Conceptions of the Bearers of Truth and Falsity, North-Holland Linguistic Series , no. 8 (Amsterdam: North-Holland Publishing Company, 1973) 192-4, for discussion. 2 Nuchelmans 192-4. 142HESTER GELBER referred to its mental equivalents, an idea Ockham rejected,3 and, in regard to the fourth question, opened the way for an expansion of the sorts of philosophical tasks mental language might perform. Much research lies ahead, both on Ockham himself and on the views of his successors, before the story will finally be told of how Ockham 's fruitful new position on mental language affected his contemporaries . We do know some of the chapters. Ockham is justly famous for having perceived mental as an ideal logical language.4 Also well known are his doubts about the ontological status of mental language and his halting progression from the "fictum" theory in which the constituents of mental language had only objective being to the "intellectio " theory in which they had subjective being.5 And, third, we know how Ockham's views developed in vigorous debate with his fellow Franciscan and critic Walter Chatton. Chatton objected to the "fictum" theory and to Ockham's contention that mental propositions are the objects of knowledge.6 There are more chapters of the story yet to be written, however. Ockham's position on mental language set off an immediate controversy , not just among his fellow Franciscans, but also among the 3 Ockham, Summa Logicae, pars I, c. 1 (OPh I, 7-8), and cf. Aristotles, De lnterpretatione, 1.16a3-9. 4 John Trentman, Ockham on Mental," Mind 79 (1970): 586-90, in arguing against Peter Geach's dismissal of Ockham's distinction between mental and spoken language as hardly more than the elimination of synonymy from mental, pointed out that Ockham treated mental as an ideal language. Cf. Geach, Mental Acts: Their Content and Their Objects (London: Routledge &. Kegan Paul, 1957) 102-4. Also see Paul Vincent Spade's comments on the importance of Ockham's views about mental language in Peter of Ailly: Concepts and Insolubles: An Annotated Translation, Synthese Historical Library 19 (Dordrecht-Holland: D. Reidel, 1980) 2-3. 5 Philotheus Boehner, "The Relative Date of Ockham's Commentary on the Sentences," in Collected Articles on Ockham (hereafter CAO) Philosophy Series, no. 12 (St. Bonaventure, N.Y.: The Franciscan Institute, 1958) 96-1 10, and idem, "The Realistic Conceptualism of William Ockham" (CAO 168-74). 6 Gedeon Gal, "Gualteri de Chatton et Guillelmi de Ockham controversia de natura conceptus universalis," Franciscan Studies 27 (1967): 191-9, and E. A. Moody, "A Quodlibetal Question of Robert Holkot, O.P. on the Problem ofthe Objects ofKnowledge and ofBelief...