Logical Human

WHAT IS A LOGICAL HUMAN?

A logical human is one who uses logic. But how? We have seen all sorts of human situations in which logic has limits. To call ourselves logical we should still use logic as far as we can, and no further. Some people see the limitations of logic and conclude that they don’t need to use it at all. But this would be like throwing away a bicycle because it can’t fly.

I believe that a logical human uses logic, but necessarily has core beliefs that they don’t try to justify. This is the starting point of their logic. Then, everything they believe should be attainable from their core beliefs, using logic. Moreover, they should believe everything that follows logically from their core beliefs, and their beliefs should not cause any contradictions.

The idea of core beliefs is analogous to the role of axioms in mathematics, discussed in Chapter 11 of The Art of Logic. Believing everything that follows logically from your core beliefs corresponds to the logical notion of “deductive closure”, which we discussed in Chapter 12. The idea that your beliefs should not cause contradictions corresponds to the logical notion of “consistency”, which we discussed in Chapter 9.

If these are the basic principles of being logical, what does it mean to be illogical? “You’re being illogical!” is used to try and shut down arguments, often by people who like to think of themselves as rational, against people who lead with their emotions (or simply anyone who disagrees with them). But two people can be logical and still disagree, if their logical systems are taking them to different places. Someone who is leading with their emotions might not be able to articulate what is logical about their thinking, but that doesn’t mean it is actively illogical.

Being illogical means doing things that go against logic, or cause logical contradictions. But I think it is important that these only really count as logical contradictions if they are contradictions within your own system of beliefs. This is a crucial point because one person’s logic might look like idiocy to another person. I think this is where the battle cry “You’re just not being logical” comes from.

Given my definition of a logical person above, there are several valid ways I could judge you to be illogical:

1. Your beliefs cause contradictions, or

2. there are things you believe that you cannot deduce from your fundamental beliefs, or

3. there are logical implications of things you believe that you do not believe.

An example of the first case is all those people who support the Affordable Care Act but not Obamacare. This causes a contradiction because ACA and Obamacare are the same thing, thus those people support and don’t support the same thing – a contradiction. An example of the second case might be things that people “just feel”, such as when they “just feel” that a relationship is not going to work, or they “just feel” that evolution isn’t right, or they “just feel” that it was definitely a vaccination that caused their child to develop autism. An example of the third case is when some men say they don’t think health insurance should include maternity cover because they don’t think anyone should have to pay for treatment for other people, and they regard maternity cover as only for women (despite the fact that it helps everyone who is born). And yet, they still think prostate cancer treatment should be covered, although that is only for men. In fact, isn’t the whole principle of insurance that you pay even when you’re not sick, so that everyone can benefit? I think the statement “I don’t think anyone should have to pay for treatment for other people” logically implies “I don’t believe in insurance”. Thus if the man in question still believes in insurance at all, he is being illogical in the third sense. (Of course, we could perform this analogy pivot and discover that probably the principle he believes deep down is that men should not have to pay for things that only affect women, but it’s perfectly fine for women to have to pay for things that only affect men.)

There are a few things to note here. First of all, contradicting someone else’s logic doesn’t mean you’re illogical. Someone might say “It’s just not logical, mathematically, to pay £50 to eat something in a restaurant when you could make it at home and spend only £5 on the ingredients.” That might be true in their system of beliefs, but in my system of beliefs it might well make sense logically to pay for the luxury of having food cooked for me instead of doing it myself. And not having to do the grocery shopping or clean up afterwards. All this doesn’t necessarily mean that I am being illogical, it just means that we have different axioms.

The next thing to note is that the question of fundamental beliefs is a grey area. Suppose someone believes, without being able to justify it, that the moon landings didn’t really happen. But perhaps they simply think of this as a fundamental belief? It might not seem very fundamental to someone else, but that’s a separate question. It comes down to the ability to follow long chains of deductions. Consider someone saying “I don’t believe in gay marriage because I believe that marriage should be between a man and a woman.” They may think of “marriage is between a man and a woman” as a fundamental belief, whereas someone else thinks of it as a constructed belief that needs justifying. Likewise if someone believes that you should only vote for someone you truly believe in. One person might think that is an axiom, whereas someone else thinks it needs justification. (I’m amazed that people who think this way ever get to vote at all, but that’s a different question.)

The question of whether or not a belief is fundamental enough to count as an axiom is very different from the question of an axiom actually being unreasonable. None of these questions is very clear cut. Even the issue of believing something “just because you feel it” could be justifiable if one of your fundamental beliefs is “everything I feel to be true is true”. (Incidentally this sounds similar but is very different from saying that feelings are always true.)

Finally note that even the third point, about believing all the things implied by your axioms, gets us into trouble with grey areas. As we discussed in Chapter 12, following the logic inexorably can push us through grey areas to undesirable extremes. For example, an apparently plausible chain of tiny increments can lead to the conclusion that it is acceptable to eat any amount of cake. The difficulty lies in how we handle the grey area along the way.

The main lesson here is that we need to understand the difference between “illogical” and “unreasonable”.