One of the first lessons of classical moral philosophy is that courage is one thing, rashness another.

Courage is cool and intelligent, whereas rashness is erratic and foolhardy. The distinction is clear enough in theory, but often hard to apply; and the new Oxford Illustrated History of Western Philosophy is a case in point. The difficulty is that the very idea of discovering a unified story-line connecting pre-Socratic prophets on the agora to postmodern professors on the Internet presupposes both a continuity in the past and a high vantage point in the present, each of which is, you might think, as improbable as the other.

In the Golden Age of the fifties, the Oxford philosophers were more circumspect. In their Encyclopedia of Western Philosophy and Philosophers (1960), they saw fragmentation and partiality as a philosophical necessity,and made a virtue of it.

“There are no authorities in philosophy,” as J O Urmson put it in his editorial introduction. Urmson’s authors disdained to pass off their interpretations as the judgment of history, and though they covered all the canonical texts, they made no attempt to couple each one to the next like railway carriages, in the way a synoptic history requires.

One might have expected this venerable wariness about the pretentions of histories of philosophy to have grown stronger with the years. Since the fifties, historians have destroyed the self-evident identity of the classical-Christian tradition in Europe, by reminding us of numerous factors which were not European, and numerous Europeans who were neither classical nor Christian. At the same time, literary critics have helped us see that what makes a text a classic is not its supine obedience to a historical timetable, but its ability to jump the hermeneutic rails and present endless new challenges to its readers.

Careless of such problems, Oxford University Press have produced a new History of Western Philosophy, aimed at the popular market. It is written by a strong team, comprising five Oxfordian professors, plus an American for the “Medieval” chapter. Between them they cover the whole spectrum of established philosophical opinion, from rather conservative to extremely conservative.

And each of them has, in his way, risen to the occasion (if that is the word), though Roger Scruton has not done much more than recycle passages from his earlier books for his egregiously complacent and opinionated chapter on “Continental Philosophy.”

Anthony Kenny is the one who has faced his responsibilities most squarely.His chapter, “Descartes to Kant” explains with terrific clarity that Descartes’s thought can be summarised in two sentences - “man is a thinking mind” and “matter is extension in motion” - and then unfolds a story about how both of them have proved to be “false”. Under Kenny’s searchlight, Descartes’s errors turn out to depend, “like all fallacious philosophical arguments,” on a failure to “pay careful attention to words and make clear distinctions wherever there is ambiguity.”

Of course Kenny knows very well that judgments of philosophical ambiguity can never be absolute: where one person detects an ambiguity, after all, another may discover a deep conceptual unity. But a book like this could not be written without such short-cuts; and indeed Anthony Quinton and Stephen R L Clarke, in their chapters on ancient Philosophy and Political Philosophy, could be reproached for being rather more thoughtful than a project like this really needs.

The illustrations are another matter. They go far beyond the familiar portraits of the men behind (so to speak) the minds, such as a noseless marmoreal head entitled “Plato’s appearance is unknown.” There is a nice colour plate from Gauguin, said to depict “The Beginning of Philosophy among a preliterate people,” and another from Salvator Rosa, intended to show what Wittgenstein meant by saying “keep silent”. There is a snap of the leaning tower of Pisa, where Galileo is supposed to have proved his law of falling bodies, although the text explains that he did no such thing; and one of Escher’s paradoxical pictures whose caption claims, quite loopily, that it proves that Frege was wrong about geometry. Descartes’s advice on how to stop your chimney smoking is also illustrated,on the homely pretext that he was “much concerned with keeping warm.”

The pictures and their captions, in short, must have been chosen by researchers who either did not read the text, or decided to send it up. And, in order to package the work as a large-format picture book which might tempt ambitious parents looking for a wholesome Christmas present, the designers have set the text in lines almost six inches long, so that the challenges it presents to the intellect are nothing to those it offers the eye. Whatever may be said of the authors, therefore, the publishers have shown little conviction in this work; and less courage.

Jonathan Ree teaches philosophy at the University of Middlesex.