We literary critics are doubtless always a little intimidated by philosophy: it refuses us the pleasures by which we set most store – the sensuous movements of language, the hilarious accidents of comedy, the surge and release of narrative, the intimacies of shared emotions, the particularities of concrete observation – and demands instead, with joyless exigency, the abstractions of pure thought, the progressions of cold logic. True, we read many philosophers with pleasure, but we do so with an edge of guilt, as we relish the modulations of their phrasing, trace their metaphorical patterns, respond to their intimations of feeling and take delight in the minute precision of their representations. At the backs of our minds is the discomfiting thought – implanted by three millennia of cultural history – that in the largest scale of things, the practice of literature can provide only an attractive garnish for the strong meat of philosophical enquiry.

When a philosopher speaks up for literature, therefore, we are quick to take notice. The literary critic who defends the status of literature is inevitably suspected of special pleading, even if the defence is couched in impeccably philosophical terms; but when we find an accredited member of the institution of philosophy – someone who in his work traverses the entire tract of Western philosophical writing – arguing that literature might hold a key to the problems with which philosophy has never ceased to grapple, our reaction is understandably different. Perhaps we're not as peripheral as we feared; perhaps we weren't wrong to believe that Dante probes as deeply as Descartes, that Aristophanes' insights are as profound as Aristotle's.