John Deely, born 1942, is the Rudman Chair in Thomistic Studies at the University of St. Thomas in Houston.
"If there is one notion that is central to the emerging postmodern consciousness, that notion is the notion of sign. And for understanding this notion, nothing is more essential
than a new history of philosophy. For the notion of sign that has become the basis for a postmodern development of thought was unknown in the modern period, and before that traces back only as far as
the turn of the 5th century AD. Yet the context within which the general notion of sign was first introduced presupposes both the ancient Greek notion of "natural sign" (semeion) and the framework of
Greek discussions of nature and mind which provoked the development of philosophy in the first place as an attempt to understand the being proper to the objects of experience. Not only does it emerge
that the sign is what every object presupposes, but, in modern philosophy, the conundrum about the reality of the "external world", the insolubility of the problem of how in theory to get beyond the
privacy of the individual mind, springs directly from the reduction of signification to representation. So here is one of the ways in which the four ages of this book can be outlined: preliminaries
to the notion of sign; the development of the notion itself; forgetfulness of the notion; recovery and advance of the notion. Tracing the development of the notion of sign from its beginning and
against the backdrop of Greek philosophy yields an unexpected benefit by comparison with more familiar historical approaches. Every modern history of philosophy has been essentially preoccupied with
the separating off from philosophy of science in the modern sense, especially in and after the seventeenth century. From this point of view, many of the continuing philosophical developments of the
later Latin centuries tend to drop out of sight. It has become the custom to present modem philosophy, conventionally beginning with Descartes (17th century), simply as part and parcel of the
scientific break with the authors of Latin tradition, and to treat the bringing of nominalism into the foreground of Latin thought by William of Ockham (14th century) as if that were the finale of
This hiatus of two and a half centuries in the history of philosophy, however, effectively disappears when we make our way from ancient to modern times by tracing mainly the
development of the philosophical notion of signum. From the High Middle Ages down to the time of Descartes we find a lively and continuous discussion of sign which, through a series of important if
unfamiliar controversies on both sides of the thirteenth century, leads to a basic split in the closing Latin centuries. On one side stand those who think that the general notion of sign is an empty
name, a flatus vocis, a nominalism, no more than a "relation of reason", an ens rationis. On the other side are those who are able to ground the general notion in an understanding of relation as a
unique, suprasubjective mode of being, a veritable dual citizen of the order of ens reale and ens rationis alike, according to shifting circumstances.
Modern philosophy, from this point of view, appears essentially as an exploration of the nominalist alternative; and postmodern thought begins with the acknowledgment of the
bankruptcy of the modern effort, combined with the determination pioneered by C. S. Peirce to explore the alternative, "the road not taken", the "second destiny" that had been identified in the
closing Latin centuries but forgotten thereafter. Peirce's postmodern resumption of premodern epistemological themes produces a number of immediately dramatic and surprising results (beginning with
the cure for the pathology dividing our intellectual culture between the personae of Dr. Jekyll and Mr. Hyde).
So derives the title for this work, Four Ages of Understanding: ancient Greek thought, the Latin Age, modern thought, postmodern thought. The book is a survey of philosophy in what
is relevant to the "understanding of understanding" from ancient times to the present. It is intended both as a reference work in the history of philosophy and a guide to future research - a
"handbook for inquirers" in history, philosophy, and the humanities generally, including historians and philosophers of science. The book also aims to aid in the classroom those professors willing to
wean a new generation from the "standard modern outlines" of philosophy's history which serve mainly to support the post-Cartesian supposition that history is of next to no import for the doing
itself of philosophy."
From: John Deely - Four ages of understanding. The first postmodern survey of philosophy from ancient times to the turn of the Twenty-first century.
Toronto: University of Toronto Press 2001. pp. XXX-XXXI.