No Truth Can Be Justified

The initial guesses at what knowledge was all about amounted to what is known as the justified true belief vision of knowledge, and it's still the most prevalent idea today. Anyone who calls themselves a Bayesian is a justified true believer, and that's the misconception that knowledge is about trying to justify as true your beliefs. And if you've done so, then you can say, "I know that thing."

So if I can justify as true my theory of gravity, then I should believe that theory of gravity, and only then can I say that it's known. The problem with this is that there is no method of showing as true any piece of knowledge.

So the improvement Deutsch promotes in his books is this vision that Popper gave us, that all we have are guesses about reality, conjectures. People think, "Oh, that sounds a bit wishy-washy; it's just a guess." Well, it's not a random guess. It's not just anyone decides to have a guess and therefore that stands on equal footing to every other.

No, it's a guess that has stood up against trials, against attempts to show that it's false. And when people are unable to show that it's false via this method of refutation, then we accept it as a piece of knowledge. This allows us to thereby accept the fact that we're going to be able to make progress in the future because all of our knowledge is conjectural.

All of it is our best guess at the time, and therefore there's this elasticity within the knowledge that allows us to say there's going to be errors. We're going to correct them and thereby be able to make progress off into the infinite future.

This is unlike the previous conception of knowledge which says once you've justified something as true, well, it's true. If it's true, that means there is nothing false about it, and therefore it can't possibly be refuted. It's a very religious notion.

The modern incantation of this is Bayesianism. Bayesianism says you have a theory, you collect more evidence, and you become more and more confident over time that your theory is correct. And it gets a little bit worse than that because then it says this Bayesian reasoning enables you to generate new theories, which you can't.

The best that it can hope to do is to show you that you are more confident in this theory than what you are in that theory. The Popperian view says if you can show that there's a flaw in a particular theory, you can discard that theory.