A Little History of Philosophy (Little Histories)

by Nigel Warburton

It was part of a movement known as logical positivism, a movement that celebrated science as the greatest human achievement. ‘Metaphysics’ is a word used to describe the study of any reality that lies beyond our senses, the kind of thing that Kant, Schopenhauer and Hegel believed in. For Ayer, though, ‘metaphysics’ was a dirty word. It was what he was against. Ayer was only interested in what could be known through logic or the senses. But metaphysics often went far beyond either and described realities which couldn't be investigated scientifically or conceptually. As far as Ayer was concerned, that meant it was of no use at all and should be ditched. Not surprisingly, Language, Truth and Logic ruffled feathers. Many of the older philosophers in Oxford hated it, which made it difficult for Ayer to get a job. But ruffling feathers is something philosophers have been doing for thousands of years, in the tradition that began with Socrates. Still, to write a book that so openly attacked the work of some of the great philosophers of the past was a brave thing to do. Ayer's way of telling meaningful from meaningless sentences was this. Take any sentence, and ask these two questions: (1) Is it true by definition? (2) Is it empirically verifiable? If it was neither of these then it was meaningless. That was his two-pronged test for meaningfulness.

If you could travel back in time to 1945 and to a café in Paris called Les Deux Magots (‘The Two Wise Men’), you would find yourself sitting near a small man with goggly eyes. He is smoking a pipe and writing in a notebook. This man is Jean-Paul Sartre (1905–80), the most famous existentialist philosopher. He was also a novelist, playwright and biographer. He lived most of his life in hotels and did most of his writing in cafés. He didn't look like a cult figure, but within a few years that's what he would become.

a human being wasn't designed to do anything in particular. Sartre didn't believe there was a God who could have designed us, so he rejected the idea that God had a purpose for us. The penknife was designed to cut. That was its essence, what made it what it is. But what was a human being designed to do? Human beings don't have an essence. We aren't here for a reason, he thought. There is no particular way we have to be to be human. A human being can choose what to do, what to become. We are all free. No one but you can decide what you make of your life. If you let other people decide how you live, that is, again, a choice. It would be a choice to be the kind of person other people expect you to be. Obviously if you make a choice to do something, you might not always succeed in doing it. And the reasons why you don't succeed may be completely outside your control. But you are responsible for wanting to do that thing, for trying to do it, and for how you respond to your failure to be able to do it. Freedom is hard to handle and many of us run away from it. One of the ways to hide is to pretend that you aren't really free at all. If Sartre is right, we can't make excuses: we are completely responsible for what we do every day and how we feel about what we do. Right down to the emotions we have. If you're sad right now, that's your choice, according to Sartre. You don't have to be sad. If you are sad, you are responsible for it. That is frightening and some people would rather...

In a lecture he gave just after the war, ‘Existentialism is a Humanism’, Sartre described human life as full of anguish. The anguish comes from understanding that we can't make any excuses but are responsible for everything we do. But the anguish is worse because, according to Sartre, whatever I do with my life is a kind of template for what anyone else should do with their life. If I decide to marry, I'm suggesting that everyone should marry; if I decide to be lazy, that's what everyone should do in my vision of human existence. Through the choices I make in my life I paint a picture of what I think a human being ought to be like. If I do this sincerely it is a great responsibility.

The Nazi Adolf Eichmann was a hard-working administrator. From 1942 he was in charge of transporting the Jews of Europe to concentration camps in Poland, including Auschwitz. This was part of Adolf Hitler's ‘Final Solution’: his plan to kill all Jews living in land occupied by the German forces. Eichmann wasn't responsible for the policy of systematic killing – it was not his idea. But he was heavily involved in organizing the railway system that made it possible.

Arendt used the words ‘the banality of evil’ to describe what she saw in Eichmann. If something is ‘banal’, it is common, boring and unoriginal. Eichmann's evil was, she claimed, banal in the sense that it was the evil of a bureaucrat, of an office manager, rather than a devil. Here was this very ordinary sort of man who had allowed Nazi views to affect everything he did.

This style of reasoning goes from ‘All the swans I've seen are white’ to the conclusion ‘All swans are white.’ But clearly a swan that you haven't observed could turn out to be black. There are black swans in Australia, for example, and in many zoos around the world. So the statement ‘All swans are white’ doesn't follow logically from the evidence. Even if you have looked at thousands of swans and they were all white, it could still be false. The only way to prove conclusively that they are all white is to look at every single swan. If just one black swan exists, your conclusion ‘All swans are white’ will have been falsified. This is a version of the Problem of Induction, a problem that David Hume wrote about in the eighteenth century. Induction is very different from deduction. That is the source of the problem. Deduction is a type of logical argument where if the premises (the starting assumptions) are true the conclusion must be true. So, to take a famous example, ‘All men are mortal’ and ‘Socrates is a man’ are two premises from which the logical conclusion ‘Socrates is mortal’ follows. You would contradict yourself if you agreed that ‘All men are mortal’ and that ‘Socrates is a man’, but denied the truth of the statement ‘Socrates is mortal.’ That would be like saying ‘Socrates both is and is not mortal.’ One way of thinking about this is that with deduction the truth of the conclusion is somehow contained within the premises and logic just teases it out. Here's anoth...

Induction is very different from this. Induction usually involves arguing from a selection of observations to a general conclusion. If you notice that it rained every Tuesday for four consecutive weeks, you might generalize from this that it always rains on Tuesdays. That would be a case of Induction. It would only take one dry Tuesday to undermine the claim that it always rains on Tuesdays. Four consecutive wet Tuesdays is a small sample of all the possible Tuesdays. But even if you make numerous observations, as with the white swans, you can still be thwarted by the existence of a single case that doesn't fit your generalization: one dry Tuesday or one non-white swan, for example. And that is the Problem of Induction, the problem of justifying relying on the method of induction when it seems so unreliable. How do you know that the next glass of water you drink won't poison you? Answer: all the glasses of water you've drunk in the past were fine. So you assume that this one will be. We use this kind of reasoning all the time. Yet it seems that we aren't completely justified in putting such faith in it. We assume patterns in nature that may or may not really be there. If you think that science progresses by induction, as many philosophers have done, then you have to face the Problem of Induction. How can science be based on such an unreliable style of reasoning? Popper's view of how science develops neatly avoids this problem. That's because, according to him, science does...

Scientists then find a way of testing this hypothesis – in this case, getting a lot of different sorts of gas and heating them. But ‘testing’ doesn't mean finding evidence to support the hypothesis; it means trying to prove that the hypothesis can survive attempts to falsify it. Ideally the scientists will look for a gas that doesn't fit the hypothesis. Remember that in the case of the swans it only took one black swan to undermine the generalization that all swans are white. Similarly, it would only take one gas that failed to expand when heated to undermine the hypothesis that ‘All gases expand when heated.’ If a scientist refutes a hypothesis – that is, shows that it is false – then that results in a new bit of knowledge: the knowledge that the hypothesis is false. Humanity progresses because we learn something. Observing lots of gases which do expand when heated won't give us knowledge, except perhaps a little more confidence in our hypothesis. But a counter-example really teaches us something. For Popper a key feature of any hypothesis is that it has to be falsifiable. He used this idea to explain the difference between science and what he called ‘pseudo-science’. A scientific hypothesis is one that can be proved wrong: it makes predictions that can be shown to be false.

Things get interesting when what Kuhn called a ‘paradigm shift’ happens. A paradigm shift is when a whole way of understanding is overturned. This can happen when scientists find things that don't fit in with the existing paradigm – such as observations that didn't make sense within the paradigm that the sun goes round the earth. But even then it can take a long time for people to abandon their old ways of thinking. Scientists who have spent their lives working within one paradigm don't usually welcome a different way of looking at the world. When they do eventually switch to a new paradigm, a period of normal science can begin again, this time working within the new framework. And so it goes on. That's what happened when the view that the earth was the centre of the universe was overturned. Once people started to think about the solar system in that way, there was a lot more normal science to do to understand the paths of the planets around the sun.

A thought experiment is an imaginary situation designed to bring out our feelings, or what philosophers call ‘intuitions’, on a particular issue. Philosophers use them a lot. Thought experiments allow us to focus more closely on what is at stake. Here the philosophical question is, ‘When is it acceptable to sacrifice one life to save more?’ The story about the runaway carriage allows us to think about this. It isolates the key factors and shows us whether or not we feel that such an action is wrong.