Intro to Critical Rationalism

There are many theories of epistemology that hold the truth to be objective, but Critical Rationalism is very different from the others.

Although it is epistemologically optimistic, in that it asserts that the truth exists and is accessible to us, it is also ultimiately sceptical, in that it asserts that we can't know the truth.

These days its fashionable to pose as falliblist. So perhaps the above does not sound so shocking. Many epistemologically optimistic positions tag on the disclaimer that the truth is never certain. But there is not much behind most of these disclaimers. Claims that the truth is never certain usually boil down to appeals to likelihood. That is to say, the kind of statements that go 'X isn't certainly true, but it is likely true.'

However, the claim the 'you believe X is true' and the claim that 'you believe Y is likely true' are not of a fundamentally different kind. Both appeal to certainty, (in one case the certainty of your belief that X is true, and in the other your certainty of the belief that Y is likely true). In summary: appeals to a theory being likely true do not take fallibility seriously.

In fact, critical rationalism is shocking because it is the only optimistic epistemology that takes seriously the arguments of scepticism. It is not just adding fallibility on as a disclaimer that has no real bearing. Critical Rationalism never purport to even know if a given theory might be true. 

Here's how it works:

Critical Rationalism puts forward the idea that knowledge improvement can occur by exposing our theories to rigorous criticism in the hope of eliminating the false theories. Karl Popper, the originator of CR, argued that there was an asymmetry between what he called 'positive reasons' and 'negative reasons'. (negative reasons being reasons against a theories, such as internal contradictions, external contradiction, falsification via empirical testing (for scientific theories), claims against its explanatory power and so on.).

This asymmetry leaves positive reasons relatively worthless--positive reasons can never really go towards verifying a theory. On the other hand, critical reasons are relatively accessible to us and can go towards falsifying a theory.

So thought we can't know if a given theory is true, we can work out if it's better than a rival theory if we show that it survives falsifation while the other theory has not.

You could look at it as the idea that we can never get close to the truth, at least we can't know that we are, but we can get further for from error, and in so doing, we can improve the state of our knowledge