The third and final problem (“Objection 3”) is contemporary philosophy’s tendency to undermine, rather than to underpin, Western civilisation. This is, in part, a déformation professionnelle: philosophers once took it for granted that they belonged at the top of the intellectual hierarchy, at least on questions of a theoretical, especially moral or metaphysical, kind. Today that doesn’t seem to happen very often. When intractable questions of ethics, politics or aesthetics preoccupy the public, one looks in vain to find philosophers consulted by the media, or by politicians, or indeed by anybody, except perhaps other philosophers. This loss of pre-eminent status has led many philosophers to question or even condemn the system that has dethroned them. The cultural amnesia of the West now means that the public square is occupied by, for the most part, argumentative individuals who have no idea how to argue. Philosophers are reduced to justifying themselves by teaching “critical thinking”, or vulgarise their own subject by affecting a frivolous manner in public. But they rarely perform their proper task of making the case for a free society against the barbarians or defending high culture against the philistines. Often, indeed, they seem to be uncomfortable with our civilisation, preferring to be destructive rather than constructive.

In defence of today’s philosophers, it must be said that most of them would deny that it is their proper task to justify anything. Ever since Socrates, who was obliged to drink hemlock for corrupting the youth of Athens, many philosophers have dismissed Objection 3 on the grounds that they must follow the dictates of reason rather than of society or the state. Some have resisted tyrants: St Anselm of Canterbury, who invented the Ontological Argument for the Existence of God, was also the first archbishop to defy the King after the Norman Conquest, protecting the liberty of the Church and abolishing slavery in England. And some philosophers have embodied what we now think of as Western civilisation. For example, Renaissance humanists such as Cardinal Nicholas of Cusa and Erasmus of Rotterdam worked to reunite Christendom, as did later philosophers such as Gottfried Wilhelm Leibniz, Benedict Spinoza and John Locke, who pioneered religious toleration. Philosophers have often led the way in championing the rights of men and women against the powers that be. Perhaps the biggest impact on recent history by a professor of philosophy was that of Karol Wojtyla, better known as Pope (now Saint) John Paul II, without whose example of defiance of the Communist system in the 1980s, the Polish people might not have begun the process that eventually brought down the Berlin Wall. But his case also illustrates that philosophy has its limits; for while phenomenology, the tradition then dominant in Poland, undoubtedly shaped Wojtyla’s intellectual formation, it was his faith that enabled him to move mountains.

One living philosopher who has profound doubts about Western civilisation but cannot be accused of obscurity is Peter Singer, best known for his radical views on animal rights, abortion and euthanasia. In a new book, Ethics in the Real World: 82 Brief Essays on Things That Matter (Princeton, £19.95), Singer demonstrates how to write pungently and succinctly about moral philosophy, though many of these brief essays are online columns from the website Project Syndicate. In one of them, he makes bold claims for philosophy, based on the 2013 rankings of the top 100 Global Thought Leaders compiled by the Gottlieb Duttweiler Institute, a Swiss think tank.