Philosophy: A Very Short Introduction

brought to remember what it then learnt of them.
Kant, who was happy to concede far more to empiricism than Plato or Hegel, met the challenge in a novel and radical way. Reason cannot tell us anything about things imperceptible—it can only tell us what, in general terms, our experience is bound to be like. And it can do this only because our experience is shaped by our own minds. Reason, operating on its own, is really only telling us how our minds work—which is why it can do what it does without needing to draw on our perceptions of the rest of the world.
Hegel’s response is not unlike Plato’s, in that he begins with a system of thoughts or universals which he collectively calls ‘The Idea’. This is the driving force which structures the whole of reality, which includes our minds and the categories in which we think, as well as the rest of reality which is what we are thinking about. That is why we can expect our reason, even when used on its own independently of perception, to be in tune with the world. The reasoning subject and its object share a structure, that of the Idea.
These three examples show us that the opposition between empiricism and rationalism is not a minor skirmish. Those who begin by taking opposite sides at this point can end up worlds apart, metaphysically speaking. But I do not mean to suggest that only rationalism faces difficulties and empiricism is problem-free. Not so, as we shall soon find out.
Another much-used ‘ism’ is scepticism. One can be sceptical, of course, about specific things like the probity of the Olympic Committee, the existence of UFOs, or the value of a low-fat diet, but when ‘scepticism’ occurs in philosophical texts it usually refers to something much more general: the rejection of a wide range of claims to knowledge, or doubts about a large class of beliefs. It isn’t just their number, of course. Any scepticism worthy of a place in the history books must be aimed at beliefs that are actually held, and are held to be important—no medals are awarded for shelling the desert.
This means that there can be plenty of thought which was sceptical in its own time, but now reads differently. A good example would be Quod Nihil Scitur (‘That Nothing is Known’), by the Portuguese philosopher/medic Francisco Sanchez (1551–1623). A more sceptical-sounding title it would be hard to find, but what follows seems to us not so much scepticism as a vigorous attack on Aristotelianism, then prevalent but now long since discredited. When sceptics succeed they cease to look like sceptics; they look like critics who were right.
Other forms of scepticism have a longer shelf-life. These are the ones whose targets are perennial human beliefs, or everyday beliefs, or what is often called common sense. The most famous example of modern times occurs at the beginning of Descartes’s Meditations, where we are threatened with the possibility that the senses cannot be relied upon to tell us anything whatever about the world, not even that there is one. But we shall see plenty of Descartes later, so let us look back instead to the school of Pyrrho (roughly: 365–275 bc), source of the most developed sceptical philosophy we know. It can all be found in a single book, Outlines of Pyrrhonism by Sextus Empiricus. Sextus, in his prime around ad 200, here reports in loving detail the aims, arguments, and conclusions of the system. Happy the movement that finds a chronicler like him.
The early pyrrhonists had worked hard. They had catalogued ten ‘tropes’, or ways of arguing for their sceptical conclusion that we have no sufficient grounds for any conviction as to what things are really like, as opposed to how they appear to us. Faced with a ‘dogmatist’—one of the politer names they called people like Aristotelians and Stoics who claimed to know such things—their favourite strategy was to find some animal to which things would appear differently, or other human beings to whom they appeared differently, or circumstances under which they would appear differently to the claimants themselves, and then to argue that there was no way of resolving the disagreement without arbitrarily favouring one viewpoint over the rest. In one passage Sextus argues that there is no reason to privilege the way something seems to a dogmatist over the way it seems to a dog. Readers will occasionally catch him arguing from premisses which a sceptic might be expected to find untrustworthy. Perhaps he, and the pyrrhonists, were not always speaking to eternity, but to their contemporaries—and felt that what they accepted could legitimately be used against them.
Nowadays one often hears it asked what the point of a comprehensive scepticism could be—asked rhetorically, with the implication that it can have no point whatever. But the pyrrhonists certainly thought that their scepticism had a point: the achievement of tranquillity of mind, untroubledness, ataraxia. They knew a thing or two about peace of mind. If you want to insist on the truth of your point of view, remember that there is a cost: life is going to be a perpetual intellectual brawl. And if the brawl stays intellectual, you’ll have been lucky; especially in religion and politics, these things have been known to end in bombs and burnings. I think they knew something else as well: moving from how things immediately appear to our senses to what they are really like is a much slower, more hazardous and laborious enterprise than many of their contemporaries realized.
The pyrrhonists’ favourite sceptical manoeuvre was to remind us that how a thing appears does not just depend on the thing: it depends on the condition of the person to whom it appears, and the medium through which it appears. Which ushers in our final ‘ism’: relativism. Relativism is not a specific doctrine, but a type of doctrine—I might add, a type much in vogue with intellectuals recently. The general idea is easy to grasp. A moral