In 1934 Karl Popper proposed judging theories not by the ability to prove them, but the ability to disprove them: falsifiability.


Hypothesis: if I drop something, then it will fall down at 9.8 m/s2.

It’s easy to check. I can drop something as often as I like, and it will fall at the acceleration above every time, verifying the result — yeah, yeah, excluding air friction. Gravity is proven, right?

This is called inductive reasoning. You do repeated observations that verify your theory.

A second example: a group of chickens lives on a farm. Every day, the farmer comes over and feeds them. Farmers feed chickens, theory proven… Until one day the farmer comes over, grabs a chicken, kills her, and eats her. Whoops.

This example is a variation of Hume’s problem. Repeated observations that something is true can’t prove it’s true in all cases.

But okay, gravity is not a person, so this doesn’t apply, does it?

Grue and bleen

Another hypothesis: if I drop something, then it will fall down at 9.8 m/s2 until a time T in the future, then gravity will reverse!

It’s easy to check. I can drop something as often as I like, and it will fall at the acceleration above every time, verifying the result — Oh… Now we’ve reached a conundrum. This makes no sense.

This example is a variation of the colors grue and bleen, devised by Goodman. Grue is a color that is green now, but will be blue after a time T. Bleen is the reverse.

Your initial reaction might be that this example is stupid, because why would a color suddenly change its properties at some point in time? Unfortunately, even that doesn’t wash: you can define the color blue as follows: blue is the color bleen, but after a point T in time it will be grue.

Yeah, that’s a bit of a mind bender, but it is technically correct.


The point of the above examples is that induction is not necessarily the best way to validate a hypothesis. Karl Popper came to the conclusion that falsifiability — disproving things — is the key.
If you look at an object before and after time T, you can easily distinguish between grue and green.
This still doesn’t prove anything for a time T in the future, but that’s where the second part of Popper’s theory comes along: the value of a theory is linked to its falsifiability.

You cannot distinguish between grue or green if T is in the future in any way. It’s not falsifiable, and Popper asserts that that means it has no practical value. There’s no practical use in distinguishing grue from green.

And Occam’s razor then states you should work with the simplest theory. In other words, green is the way to go.

More practical

So far, this has been a pretty theoretical exercise. Let’s turn to something more practical. Say, for example, that somebody was to assert — oh, I don’t know — that the world was ruled by a secret cabal of pedophiles. Or that Covid was a hoax to inject us with microchips. Or that vaccines are killing our children!

The adherents will say that, of course those theories are true, even if there’s no hard proof. Because they explain so much. Also, the people in charge are masters of covering things up. And look at all those sick children. Yeah, even the media are in on it, giving out fake news.

I personally think that’s complete horseshit, but it is true that the observations do fit the theory, or the theory is expanded to make it so. Like with grue and bleen. In other words, inductive reasoning.

If we apply Popper, there is no value in assuming a worldwide pedophile cabal, or the assumption that vaccinations are deadly, unless you make it falsifiable. Guess what, most followers don’t actually want it to be disprovable. They pose questions, but they won’t believe answers because those come from ‘the mainstream media, who are in on it’. Everything that could disprove the theory, even the absence of proof, are twisted to be inductive proof instead.

Millions have been spent on vaccine research, proving vaccines are safe, but anti-vaxxers continue to doubt. During pizzagate, a guy with an assault rifle held a pizzeria at gunpoint looking for a pedo-basement which did not materialize. But still the theory persists.

So we can apply falsifiability: since there’s no way to disprove these theories, they have no value. Then comes Occam’s razor and the simpler theory persists: there is no worldwide cabal of pedophiles, Covid is not a hoax, and vaccines do work.

What will disprove it for you?

If you’d asked me two year’s ago if there was a billionaire with a private island used to sexually abuse young girls, I would have said I doubted it. Then, it turned out that there was. Well, shit. Guess I was wrong. It’s horrible this happened, and anybody who knowingly participated in this should be arrested and thrown into a very deep hole.

But does this mean there is a worldwide hidden pedophile cabal in charge? Induction points to at least some cases of it, but that doesn’t mean this is true for all cases. See above. That said: show me falsifiable proof and I will change my mind.

If you take anything from this post, let it be this: for everything you believe, ask yourself what it will take to disprove it to you. If the answer is ‘nothing can’, ‘it would be possible, but I actually never looked into it’, or ‘I really don’t understand these experts’, then you should seriously ask yourself if you should be basing decisions on that belief.

Impossible to disprove the pedophile cabal to you? Maybe don’t go shooting politicians.
You truly believe 5g causes Covid even though there’s a shitload of evidence it doesn’t? Maybe don’t burn down a radio mast. And read up on radiation. You’re afraid your kid will get autism from vaccines and you still won’t trust a gazzillion studies disproving that? Don’t risk your kid dying of measles. And secondly, stop being an autism bigot.


Don’t believe convoluted shit that cannot be disproven. It doesn’t make you enlightened, it makes your views worthless.

Always leave room for doubt.

Martin Stellinga Written by:

I'm a science fiction and fantasy writer from the Netherlands