Mental Language: From Plato to William of Ockham

Mental Language: From Plato to William of Ockham

Mental Language: From Plato to William of Ockham

Mental Language: From Plato to William of Ockham


The notion that human thought is structured like a language, with a precise syntax and semantics, has been pivotal in recent philosophy of mind. Yet it is not a new idea: it was systematically explored in the fourteenth century by William of Ockham and became central in late medieval philosophy. Mental Language examines the background of Ockham's innovation by tracing the history of the mental language theme in ancient and medieval thought.

Panaccio identifies two important traditions: one philosophical, stemming from Plato and Aristotle, and the other theological, rooted in the Fathers of the Christian Church. The study then focuses on the merging of the two traditions in the Middle Ages, as they gave rise to detailed discussions over the structure of human thought and its relations with signs and language. Ultimately, Panaccio stresses the originality and significance of Ockham's doctrine of the oratio mentalis (mental discourse) and the strong impression it made upon his immediate successors.


This book is the result of a project originally much more narrowly circumscribed: it aimed to trace the theoretical discussions of the period (from approximately 1250 to 1320) that led to William of Ockham’s theory of mental language (oratio mentalis). At the time, I was guided by two motivations that I feel it is appropriate to describe here, as they remained decisive throughout my research.

On the one hand, I asked myself whether these scholastic debates, seemingly so different from our own and quite often conducted in a theological context, nonetheless had some relation to the problem of the “language of thought” that is treated in contemporary cognitive science. the very possibility of an intellectual conversation with authors as distant from us as the medievals was called into question in the 1960s, thanks to the spectacular success of such notions as rupture, incommensurability, and paradigm shift. But perhaps the conclusions and hypotheses of Thomas Kuhn and Michel Foucault have been too readily accepted. the question, it seems to me, should be addressed in terms of detailed analyses of particular cases; indeed, the topic of mental language would especially seem to demand such treatment.

On the other hand, recent work by historians of ideas—in particular, William Courtenay, Zenon Kaluza, and Katherine Tachau—has forcefully demonstrated the need to reevaluate the place of William of Ockham in the history of later medieval philosophy, as well as the impact of his work on his immediate contemporaries and successors. Tachau, for example, maintained (in an important work that appeared in 1988, Vision and Certitude in the Age of Ockham) that the Ockhamist theory of knowledge was quite poorly received in the universities of the day and did not lead to the establishment of a philosophical school. However, Tachau’s inquiry was restricted to select themes—namely, those surrounding intuitive cognition (notitia intuitiva) and the mental image (the species). It seemed to me that a similar study of the idea of mental language, central for the venerabilis inceptor, could perhaps act as a counterweight and in any case would provide a useful completion of the portrait. My hypothesis was—and still is—that William of Ockham accomplished, in the years 1315–25, a major and highly influential theoretical revolution, precisely through the development of the concept of oratio mentalis.

It quickly became clear, however, that I would need to move beyond the limited chronological frame to which I had initially confined myself in order to allow a detailed reexamination of the topic’s Greek, Roman, patristic, and Arab sources, as well as of the entire medieval development of the theme since Anselm of Canterbury in the eleventh century. For not only did the texts of Aristotle, Augustine, Boethius, and John Damascene (as well as those of Anselm), on . . .

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