任何真理都无法被证明No Truth Can Be Justified
Brett：人们对"知识"的最初猜想，就是所谓"确证的真信念"（justified true belief）的知识观，直到今天它仍是最主流的观念。任何自称贝叶斯主义者的人，都是"确证的真信念"的信徒。
这种误解认为，知识就是努力把自己的信念确证为真。如果你做到了，就可以说："我知道那件事。"如果我能把我的引力理论确证为真，那我就应该相信这个引力理论，也只有到那时才能说它是"已知"的。
问题在于，没有任何方法能证明某条知识为真。多伊奇在书中推崇的，正是波普尔给我们的这个观点：我们拥有的只是对现实的猜测，都是猜想。
人们会想："哦，这听起来有点含糊其辞，不过是个猜测而已。"其实不然，它不是随机的猜测，而是经受了考验、扛住了各种试图证明它为假的尝试的猜测。并不是每个抛出猜测的人都站在同一起跑线上。
当人们无法用证伪的方法证明某件事为假时，我们就把它当作一条知识接受下来。这让我们能够接受这样一个事实：我们将来还能取得进步，因为我们所有的知识都是猜想性的，全都是当时的最佳猜测。
知识本身具有弹性，让我们可以说："会有错误。我们会纠正它们，从而能够向着无限的未来不断进步。"
这与以往的知识观截然不同，后者认为："一旦你把某件事确证为真，它就是真的。"如果它是真的，就意味着它没有任何虚假之处，因此不可能被证伪。这是一种非常宗教化的观念。
这种观念的现代化身是贝叶斯主义，它说："你有一个理论，收集更多证据，随着时间推移你就会越来越确信自己的理论是正确的。"
情况还会更糟一些，因为它接着声称："这种贝叶斯推理能让你产生新理论。"它做不到。它最多只能告诉你，你对这个理论的信心比对那个理论更强。
波普尔的观点是："如果你能指出某个理论存在缺陷，你就可以抛弃那个理论。"
Brett: 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 themself a Bayesian is a justified true believer.
This is the misconception that knowledge is about trying to justify your beliefs as true. And if you’ve done so, then you can say, “I know that thing.” 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 any piece of knowledge is true. The improvement Deutsch promotes in his books is this vision that Popper gave us, that all we have are guesses about reality. They’re conjectures.
People think, “Oh, that sounds a bit wishy-washy. It’s just a guess.” Well, it’s not a random guess. It’s a guess that has stood up against trials, against attempts to show that it’s false. It’s not that everyone who decides to have a guess stands on equal footing.
When people are unable to show that something’s false—via this method of refutation—then we accept it as a piece of knowledge. This allows us to 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.
There’s 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 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. That’s a very religious notion.
The modern incantation of this is Bayesianism, which says, “You have a theory, you collect more evidence, and you become more and more confident over time that your theory is correct.”
It gets a little bit worse than that, because then it says, “This Bayesian reasoning enables you to generate new theories.” Which it can’t. The best that it can hope to do is to show you that you are more confident in this theory than 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.”