Thoughts on Falsifiability and Popper

One should design experiments that would show that false theories are indeed false. But generally, one should design experiments to show that something is true.

If it is not true, then it should be possible to use the results of the experiment to demonstrate that.

So, in that sense, it is indeed important to be able to show that a hypothesis is false, if it is.

And of course, some experiments are designed specifically to show other theories are false. There is an important place for such theories in science.

Take the experiments performed by Louis Pasteur which disproved the theory of spontaneous generation. This experiment was designed to show that spontaneous generation was invalid and it was a remarkably successful demonstration.

Or take Galileo’s experiments which validated his theories about motion. These experiments disproved Aristotle’s misguided physics of motion.

So, yes, there is a place in science for disproving existing theories.

However, the primary focus of experimental science is usually to prove the truth of some hypothesis.

Which often has the consequence of disproving other theories which happen to be shown to be wrong.

And as stated, it is true that if a theory is wrong, then it should be possible to falsify the theory. Where reasonably possible, experiments should be designed to make it possible to show that the theory is false.

Scientific Certainty

It should be noted that some things are not falsifiable. In the sense that they cannot be proven to be false.

So, yes, in this respect, it is important to make sure that false theories can be falsified.

However, Popper believed that science cannot hope to prove theories, only to falsify and thus invalidate theories.

This is not the case. You can prove some theories beyond any shadow of reasonable doubt.

For instance, it is impossible to falsify the claim “the sun is a star”. The sun is a star and nothing will ever show that it is not.

Does this mean that such theories are unscientific? No. We are entitled to such certainty regarding these theories precisely because we have correctly followed a proper scientific method to develop rigorously scientific theories.

To do so, we use epistemological methods such as induction which Popper considered to have no place in science.

Popper considered scientific certainty and settled science to be unscientific. This is not a valid position.

There are theories which we can be certain will never be proven wrong. We can be certain that we understand the facts well enough to at least say that the central tenets of the theory are true!

For instance, take evolution. This is the only viable theory that explains the amazing biodiversity we see around us. According to Popper, are we then to question that we do not understand evolution or that it does not explain biodiversity?

Indeed, we may not understand all the details of the theory. But that does not mean that the central tenets of the theory are wrong. It just means we have not worked out all the details or its implications.

Sorry Darwin, your immensely inductive theory of evolution? Turns out that we should find alternatives to it. I hope the Creationists do not find out about t his….

Popper takes this further. He has this to say if you find yourself with only one theory that explains the facts:

Whenever a theory appears to you as the only possible one, take this as a sign that you have neither understood the theory nor the problem which it was intended to solve.

Karl Popper, Objective Knowledge: An Evolutionary Approach (1972)

This is consistent with the view that you can never prove a theory to be true. If that is the case, then there could not be any reason to be sure that you ever have the right theory. Perhaps you simply have not falsified this great theory. But you might tomorrow!

So, of course, Popper would have us not having one provably true theory of how biodiversity arises on earth, which is Darwinian evolution. We should apparently be wary of this and accept other alternatives.

In the real world, we know beyond any reasonable doubt that evolution is the primary explanation for biodiversity. Few rational people would consider that there are any viable alternatives

I would insist that it is not in the vein of rational or scientific thinking to entertain baseless doubt. Or to insist that scientific certainty is not possible.

You can read more about scientific certainty here.

Popper was, like many of his peers, in denial about the true, valid purpose of the sciences. He did not accept that the primary purpose of science was to develop theories about the world which one could then show to be true.

Instead, he was happy to develop descriptions which one had not yet invalidated. As though that was the purpose of science.

What If We Have Multiple Theories?

Popper seems to think it is bad if we have only one theory, this is bad news. So, given multiple theories that might seem to describe the same thing, which should we prefer?

Popper does give us guidance as to how he thinks we should assess whether one theory is better than another.

We do not use induction to see which better explains the facts. Instead, we test both theories and see if one is falsified. If neither is falsified, then the theory with better predictive power is to be preferred.

Thus, when assessing Newton’s and Einstein’s theories of gravity, we should not use induction to see which better explains the facts of reality. We should see whether we can falsify one and if not see which makes better predictions.

Karl Popper the originator of falsifiability
Lets consider Popper’s philosophy of science conclusively falsified…

In other words, which theory is better corroborated?

But such corroboration should only count if it is the result of a “risky” prediction. That is one which could have falsified the theory.

If it survives this attempt at falsification, the theory should be considered corroborated.

That does not verify that the theory is true. It just means that according to Popper, we have good reason to prefer this theory over others that may have less such corroboration.

And the more “risky” the predictions it survives, the better.


Popper’s approach to science is invalid. We should try to prove that a theory is true and for this we need induction.

If we use induction and proper experimental methods, we can show beyond any reasonable doubt whether a theory is true or false.

Yes, it is important to be able to show that a wrong theory is wrong. We should design our experiments so that we can show that a false theory is indeed false.

But it is not true that the best we can do in science is hope that a given theory will not be shown to be false. It is not true that the primary purpose of science is to try to falsify theories.

It is to learn about reality by postulating theories and then showing them to be true or false.

When we are wrong, we work on developing a better understanding of reality and coming up with better theories.

But we do not give up on being right or trying to show that we are right. The ultimate goal of any science should be certainty regarding how the world works. Even if Popper disagrees with this.

Falsifiability is not the central issue here and being able to try to falsify ideas is not the main goal in science. Learning about reality is.

Yes, it is important to be able to falsify theories. But the point is that is not the primary purpose of science.

Let us focus on the certain knowledge of how the world works and not trying to show that we are wrong all the time…

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