The assumptions inherent in all science

Science is very important. If it wasn’t for science, we wouldn’t know very much at all. Science, in a very broad sense (learning about the world from repeated empirical observations) has presumably been going on at least as long as humans have existed, and probably earlier. More formal, rigorous approaches have been developing as civilisation has become more advanced, culminating in what’s now known as The Scientific Method™.

The Scientific Method™ is often considered to be pretty much infallible with regard to determining facts about how the universe works. You make observations. You make a hypothesis to explain them. You use that hypothesis to make testable predictions. You do experiments to check whether the predictions are correct. If the predictions are wrong, you make a new hypothesis. If they’re right, and you can repeat the experiment and get the same results, then you’ve got a theory, and after a while, if nobody can prove it wrong, everyone just sort of accepts that it’s right.

But we’re still actually dealing with a fuckload of assumptions, that we have no real justification for, but we kind of have to stick with if we’re going to be able to do science.

Assumption 1: My senses present the world to me in a way that has some relation to the way the world is

I’ll admit, this one is a bit silly. The problem is, though, it’s very difficult to disprove. Descartes tried it, but just ended up digging himself into a massive hole with an argument about an Evil Demon that’s putting ideas into my mind and couldn’t really get out of it without some very dodgy reasoning.

The philosophical establishment seems to have largely given up at trying to rigorously prove that there’s not a Cartesian Evil Demon. Instead, we’ve got things like George Edward Moore’s argument:

  • p1: *holds up hand* “Here is a hand”
  • p2: *holds up other hand* “Here is another hand”
  • Therefore external objects exist.

Or Wittgenstein’s argument that we can’t disprove global skepticism but we still shouldn’t take it seriously because then we wouldn’t be able to do any philosophy or science or anything really.

Of course, if we don’t know whether there is an external world at all, we can’t do science, so we just assume that our senses are basically reliable (barring known exceptions such as optical illusions, dreams, intoxication etc., and with the help of scientific instruments).

Assumption 2: Induction works

Science is based on the idea that, if something’s happened lots in the past, it’s going to happen again in the future. That’s how you make predictions from a hypothesis. Karl Popper tried to say science doesn’t use induction, but if you’ve ever actually studied science you’ll know that it totally does. That’s why you repeat an experiment lots of times, and the more times you repeat it and get the same result the more seriously that result is taken.

The problem here is that, as pointed out by David Hume, 18th Century Scotland’s greatest troll, there’s no way to know that induction actually works. The fact that the sun has risen every day in the past is not a good reason to believe that it will rise tomorrow. Much like global skepticism, this turns out to be very difficult to argue with. I could say induction has always worked in the past, but that would be circular.

Again, we kind of have to stick with this assumption, otherwise we wouldn’t be able to do science.

Assumption 3: The Cosmological Principle

The Cosmological Principle is the idea that the universe is basically the same wherever you’re looking from. There are no particularly privileged viewpoints. Essentially, it can be viewed as a spatial analogue of the induction principle. According to the induction principle, a physical law that has been observed in the past will also hold in the future. Similarly, according to the Cosmological Principle, a physical law in one part of the universe also holds everywhere else.

Much like induction, this is essential to make predictions about distant parts of the universe, but it is also subject to a similar problem. Empirical evidence of the Cosmological Principle consists of the fact that the universe looks roughly isotropic and homogeneous from Earth, and then the generalisation from that to the idea that it looks isotropic and homogeneous from everywhere because Earth isn’t special. This is clearly circular. We have no good reason to use the Cosmological Principle, but we kind of have to in order to study the universe.

Assumption 4: Occam’s Razor

Occam’s Razor is the well-known idea that a scientific theory should not use more concepts than are necessary to explain what it explains. You should prefer simpler theories. This isn’t especially critical, and is generally overridden when a more complicated theory has greater explanatory power than a simpler one. However, it is still used to choose which of two theories to prefer, all other things being equal.

But there’s no reason to believe simplicity leads to truth. It’s just a rule of thumb, nothing more. It’s used largely arbitrarily, because we need some way of distinguishing between theories and choosing which to investigate. It’s another unjustified assumption that we need for science to work.


We need these assumptions. Sure, science is not totally justified, but we still need science. Without science, we wouldn’t be able to know anything. As Wittgenstein pointed out, if we were to take this kind of skepticism seriously, it would end up getting silly. We wouldn’t be able to function. So we need to assume things. Maybe somewhere else, there are some aliens that have developed a scientific method with different, but similarly arbitrary, assumptions, and come to different conclusions that still work. But we can’t do away with arbitrary epistemological assumptions altogether and expect to have a functional civilisation.

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