Holding positions rationally

Many people seem to think that rationality consists of holding certain positions that are justified (shown to be true or probably true) – justified true belief. For example, you are supposedly rational if you think that life evolved by natural selection and creationists are irrational. Why? One common answer is that there is lots of evidence for evolution. Thus evolution is not just a theory it is a proven scientific fact or something like that. If you don’t look at this story too closely, you might think it makes sense. There is a lot of evidence that is relevant to the theory that life evolved on Earth by common descent from a single ancestor. However, the idea that positions can and should be justified – justificationism – is a gross misrepresentation of science and rationality more generally.

If you were looking for flaws in justificationism, it wouldn’t be difficult to find them. Newtonian mechanics was not contradicted by the vast bulk of experimental evidence before the 20th century – that’ two hundred years of positive experimental results. But Newton’s theory was replaced by quantum mechanics and general relativity, which contradict one another so they can’t both be true. We don’t know what the replacement will be and it may be the case that there is stuff physicists have badly misunderstood at the foundations of both theories. If physicists are almost certainly misunderstanding a whole load of stuff and don’t have a consistent worldview then it can hardly be said that physics is justified. So by justificationist lights, the whole of physics is irrational.

I picked physics, but I could have picked many other subjects. In biology we don’t understand what sort of complexity DNA can be used to create as a result of natural selection. Would it be possible to evolve creatures that travel through space and colonise other planets purely by natural selection among genes? Human beings haven’t created knowledge about space travel in that way. Rather, we have created a lot of that knowledge through evolution of ideas. And we have virtually no understanding of how evolution of ideas is instantiated in the brain.

And then there’s everyday life. Let’s take brushing you teeth. Can you justify brushing your teeth? People seem to end up doing stuff that is widely recognised as irrational when they undertake activities like politics, personal relationships, work, money, drugs, food, exercise and other stuff. But a lot of it is the same old shit people have been doing for centuries. So what’s the hold up? Why hasn’t it been justified yet and so made rational? Many people will say that such stuff is necessarily irrational. Why? Because we’re apes or something comes the vague reply. This reply doesn’t make sense because it doesn’t explain why all this stuff should be irrational while science is supposedly rational.

Rationality isn’t about the content of your positions, it’s about how you hold them. Justification is not any part of rationality, because justification is impossible. Any argument has to start with premises, so if the premises are not justified nor is the conclusion. And if you try to justify the premises then you need another argument, with more premises that have to be justified.

“Aha!” I hear you cry, “I have got you. For I can look out of my window right now and see lots of stuff like a white van. I can base my worldview on these observations.” This is a terrible argument. Eyewitness testimony is notoriously unreliable. People often misunderstand stuff they see quite badly. They make up stories to try to explain what they see after the fact and this can change what they think they saw.

And people don’t understand the vast majority of what they see. For example, there are some rain drops on my window. Those raindrops are refracting the light from the scenery in front of the window: they bend the path the light takes away from a straight line. I can see colours in each raindrop because it takes the light from some piece scenery and bends it in such a way that it enters my eye and I see it. The optics of visible light for an object as large as a raindrop is fairly well understood. Given enough time I might be able to reproduce what I can see through the raindrops. Most people couldn’t do that calculation since they don’t know the relevant physics, and I’m just not going to do it because it’s not interesting. Now, think about how much stuff in everyday life you don’t understand at that level of detail and you’ll begin to see a problem in taking what you see as totally unproblematic.

So if justification is impossible how can we think and act rationally? What’s needed is a way to try to sort bad ideas from good ones. The way to do that is to take your ideas seriously as descriptions of how the world works and look for problems with them – anything that seems unsatisfactory. You then propose solutions to those problems and look for problems with the solutions until only one is left. Then you start on another problem. Rationality is about solving problems and then moving on to new problems you prefer to the old ones. It’s not about fixing some particular idea in stone. Rather, it is about improving ideas

To the extent that we have succeeded in creating knowledge in subjects like physics and biology, it’s because people have found lots of flaws with their past ideas and discovered new ideas that don’t have those flaws. They have other flaws that are more interesting.

By contrast, it is notable that when it comes to things like politics and personal issues people seldom admit error and almost never look for explanations. For example, when people get married they become dependent on one another to some extent because their finances are bound together, unless they specifically stipulate otherwise in a prenup and prenups can be overturned. But why should two adults be financially dependent on one another? Most of them could afford to rent ¬†or buy an abode on their own. Food is cheap. Lots of people could live near to where they work and to shops so they wouldn’t need a car. Many people say marriage is good for raising children, but lots of married people get divorced and hurt their children in the process. There is a lot of stuff here that just doesn’t add up at all and very few people are looking for alternatives.