What Is a Reasonable Human?

WHAT IS A REASONABLE HUMAN?

I will judge you to be unreasonable if I think your fundamental beliefs are not reasonable. But this might not mean you're contradicting logic, it just means we have some fundamental disagreements. If two mathematical systems have different axioms they do not disagree – they are just different systems, and the best we can do is discuss which system is a better model of the situation in question.

We should acknowledge that what counts as a "reasonable" fundamental belief is a grey area, and is an unavoidably sociological concept: different cultures count different things as reasonable. However, I think a key component of "reasonableness" is that there should be some sort of framework for verification and adjustment.

If one of your core beliefs is that the moon is made of cheese, I would say that this is not reasonable, although it makes for fun fiction (as in Wallace and Gromit's A Grand Day Out). But what is my framework for thinking this? First of all, by a logical argument: cheese is a product of milk, and milk comes from animals. How could all that milk product have got into orbit? Secondly, an argument by evidence: people have been to the moon and brought back dust, and it was not cheese.

Of course, there are some people who believe that the moon landings were fake, and that all the evidence about them is part of a huge conspiracy. I would also say this is not reasonable, because I believe in scientific evidence as one of my core beliefs.

Before we go further we should note that there are some axioms that don't really need to be reasonable: those that are more like personal taste. We are allowed to like and dislike food, like and dislike music. But even those tastes can sometimes be justified further. I used to think my dislike of toast was simply an axiom of mine, but people challenged it so often that I have now explained it more fundamentally by the fact that I don't like crunchy things, and that is because it feels violent to chew them. You might think I'm absurd, or ridiculously sensitive, but I think it's within my rights as a reasonable person to decide I don't like the feeling of chewing something crunchy.

Aside from outright contradictions it is hard to talk about what counts as reasonable core beliefs without being stuck floating in a space of relativism: you might worry that I can only call someone's beliefs unreasonable relative to mine, at which point they can call mine unreasonable relative to theirs, and indeed many arguments take this futile form in which both sides call the other unreasonable and no progress is made.

Setting aside questions of personal taste, there is one criterion for reasonableness that I think has a chance of not being relative, and the clue is right there in the word "reasonable": are your beliefs open to being reasoned with? That is to say, are you open to changing them? Do you have a framework for knowing when it is time to change them? Are there any circumstances at all under which you would change them?

In one of my favourite moments of Macbeth, Macduff is trying to persuade Malcolm to come back from exile and fight Macbeth for the throne of Scotland. Malcolm has a clever and wise way of discerning whether or not this is a trap to lure him to danger. He starts portraying himself as a terrible person, and describes what a cruel and evil king he would be. He needs to see whether Macduff's support of him is rational or not. If it is rational, then in the face of Malcolm's admissions he will withdraw his support. If he does not withdraw his support, Malcolm will conclude that the support is not rational and he is therefore not to be trusted. In the event, Macduff despairs and cries, "Oh Scotland, Scotland!" and withdraws his support, determining to leave Scotland himself forever. Because Macduff withdraws his support in the face of the supposed new evidence showing how unsuitable Malcolm is to be king, Malcolm is reassured that the support is rational.

I think this openness to changing one's conclusions or axioms in the face of evidence is an important sign of rationality. If someone continues to support a person or idea or doctrine regardless of further and further evidence then this is a sign that the support is blind rather than rational. There is a difference between loyalty and blind support, and a difference between healthy scepticism and science denial. I think it's an example of fuzzy logic. Loyalty means not changing your support over minor issues. Blind support means not changing your support over major issues, or any issues at all. Of course, a question remains over what counts as "major" and "minor" issues.

Here are some things I have changed my mind about over the years. I have already mentioned compulsory voting in Chapter 13. I also now support liberal arts education because I see that this can happen either informally (as in the education I received) or formally (as in the US system). I now support a more active form of feminism because I see that the passive form was not achieving the change I want to see. I (grudgingly) support getting up early, because I've discovered it helps me lose weight, possibly for hormonal reasons. And I believe in doing things for myself, not just for other people, because I see that if I neglect myself I reduce my ability to do things for other people.

If I examine these cases carefully I see that I have changed my mind about axioms from a combination of logic, evidence and emotions. Even if it's not explicit, there is some kind of framework there.