Prime Platonism: Why I Only Believe Prime Numbers Are Real

Quining the non-prime

Quine famously thought that you should only believe in some entity if it is indispensable for our best scientific theories (well, if he existed, I argued against that last year). For example, to make sense of math, you need to invoke sets, and math is needed for science, so you should believe in sets. I agree wholeheartedly. But lots of people nonetheless see the need to invoke other strange, aberrant entities—composite numbers, numbers that have more than two factors.

I don’t believe in composite numbers. So my view is that 1—exists. 2—exists. 3—exists. 4, however, doesn’t exist, nor does 6, 8, 9, 12, 14, 15, or any other composite number.

Why believe in these strange, aberrant entities, like 4, and 6? Prime numbers I can understand—nothing weird about them. But composite numbers seem deeply strange—as Mackie said, too strange to be part of the fabric of the universe. I’ve certainly never seen a composite number.

And it doesn’t do any work explaining anything! Composite numbers are the product of primes. So anything you can use a composite number to explain can be explained by prime numbers. Just as you don’t need to invoke mathematical facts if you can just invoke sets, you don’t need to invoke composite numbers—you can just invoke prime numbers.

For example, suppose you want to know how tall a statue is that’s 5 times taller than a 3 foot man. The answer: 5x3 feet! See, no need to invoke weird things like composite numbers.

People’s only argument for there being composite numbers is that it seems that there are. But, so what? Evolution would make it seem like there are a lot of composite numbers even if there weren’t any. It improved our survival to believe in lots of fictions—why can’t composite numbers be one of them?

And cultures disagree massively about composite numbers. For example, what’s the composite number you get when you add two to itself—the English say it’s four, the French quatre, Hebrew speakers say ארבע, the persians say چهار! That’s a huge amount of disagreement! If there’s this much error about the composite numbers, why trust our intuitions about them at all?

Yuval Noah Harari says that human rights are just fictions, like Gods. So are composite numbers. If only the people so ready to reject other kinds of dogma, like it being wrong to torture people for no reason, were equally willing to reject the dogma that they like—the existence of composite numbers.