Critical Rationalism Overview [CF Article]

Ironically, it’s commonly the authority of reasoned argument that’s appealed to for justification (This is ironic because intellectual authority is contrary to reason.). People say their rational arguments are the authority justifying their claims.

Doesn’t DD say we have tentative justification to act on an idea (like not jumping off a building) if it’s based on a good explanation (like the theory of relativity)?

Are you saying rational argument can’t provide tentative justification to act on an idea? Or that it can’t be used as a justification that an idea has been verified with certainty?

“I believe that we can justify our expectation that the Floater would be killed. The justification (always tentative, of course) comes from the explanations provided by the relevant scientific theories. To the extent that those explanations are good, it is rationally justified to rely on the predictions of
corresponding theories.”

-FoR, Chapter 7

Yes, that was actually one of the last public debates between ET and DD.

ET, with KP, denies that we can have justification. They deny that surviving criticism or criticism of rivals is positive justification. They think criticism and error correction are our tools, and contrast critical and positive arguments.

DD claims that justificationism involves infallibilism which is why it’s bad. He says that it’s wrong to call him a justificationist because he’s a fallibilist. ET and KP think justificationism is about using positive (aka justifying or supporting) arguments, not about fallibilism.

DD also claims that fallible justificationists, such as the typical Bayesian at Less Wrong, are logically inconsistent – their justificationism and fallibilism contradict. But he retreated from debate (and started privately messaging debate participants to trash talk ET) without saying what the contradiction was.

CF agrees with CR’s refutations of all justification of ideas (that is, refutations of positive arguments). Surviving criticism, and criticism of rivals, are not justifications/positive arguments. No one has proposed some sort of justification/positive arguments that would work.


I tried to find an example of DD saying something like that. Do you think these are good examples?

“…isn’t it a strange assertion you are attributing to Popper, that the reliability of a theory depends on the accident of what other theories — false theories — people have proposed in the past, rather than just on the content of the theory in question, and on the experimental evidence?”

“Popperians might speak of a theory being the best available for use in practice, given a certain
problem-situation. And the most important features of a problem-situation are: what theories and explanations are in contention, what arguments have been advanced, and what theories have been refuted. ‘Corroboration’ is not just the confirmation of the winning theory. It requires the experimental
refutation of rival theories. Confirming instances in themselves have no significance.”

-Both from FoR Chapter 7

“CRYPTO-INDUCTIVIST: I see. Argument is not the same species of thing as deduction, or the non-existent induction. It is not based on anything or justified by anything. And it doesn’t have to be, because its purpose is to solve problems — to show that a given problem is solved by a given

-FoR Ch. 7

But then earlier he says:

“CRYPTO-INDUCTIVIST: That’s news to me, and I’ve studied Popper extensively. But anyway, what is the solution? I’m eager to hear it. What justifies the prediction, if it isn’t the evidence?
DAVID: Argument.
DAVID: Only argument ever justifies anything — tentatively, of course.”

-FoR Ch. 7

It sounds to me like he’s saying that argument itself isn’t justified by anything like axioms or proof. But decisions made based on rational argument can be justified.

I had a question about justification. For example, imagine someone asked me why I would rather take the elevator than jump from the roof of a building. I might “justify” my choice by saying that according to our best explanations for how reality works I would (at least) severely injure myself if I jumped from the roof of the building. I don’t think that implies that surviving criticism provides positive support to any remaining theories. Aren’t they different ideas?

“Obviously the reason why you are not even now leaping over this railing is, in part, that you consider it justified to rely on our best theory of gravity and unjustified to rely on certain other theories.”

-FoR Ch. 7

Thanks for your response, it was very helpful.


It converts the quest for truth into a quest for certainty (a feeling) or for endorsement (a social status). This misconception is called justificationism.

The opposing position – namely the recognition that there are no authoritative sources of knowledge, nor any reliable means of justifying ideas as being true or probable – is called fallibilism.

I think that’s wrong. Some quotes from a 2013 email by me:

Justificationism is not necessarily infallibilist. Justification does not mean guaranteeing ideas are true or probably true. The meaning is closer to: supporting some ideas as better than others with positive arguments.

Realism and the Aim of Science, by Karl Popper, page 19:

The central problem of the philosophy of knowledge, at least since the Reformation, has been this. How can we adjudicate or evaluate the far-reaching claims of competing theories and beliefs? I shall call this our first problem. This problem has led, historically, to a second problem: How can we justify our theories or beliefs? And this second problem is, in turn, bound up with a number of other questions: What does a justification consist of? and, more especially: Is it possible to justify our theories or beliefs rationally: that is to say, by giving reasons – ‘positive reasons’ (as I shall call them), such as an appeal to observation; reasons, that is, for holding them to be true, or at least ‘probable’ (in the sense of the probability calculus)? Clearly there is an unstated, and apparently innocuous, assumption which sponsors the transition from the first to the second question: namely, that one adjudicates among competing claims by determining which of them can be justified by positive reasons, and which cannot.

Now Bartley suggests that my approach solves the first problem, yet in doing so changes its structure completely. For I reject the second problem as irrelevant, and the usual answers to it as incorrect. And I also reject as incorrect the assumption that leads from the first to the second problem. I assert (differing, Bartley contends, from all previous rationalists except perhaps those who were driven into scepticism) that we cannot give any positive justification or any positive reason for our theories and our beliefs. That is to say, we cannot give any positive reasons for holding our theories to be true. Moreover, I assert that the belief we can give such reasons, and should seek for them is itself neither a rational nor a true belief, but one that can be shown to be without merit.

(I was just about to write the word ‘baseless’ where I have written ‘without merit’. This provides a good example of just how much our language is influenced by the unconscious assumptions that are attacked within my own approach. It is assumed, without criticism, that only a view that lacks merit must be baseless – without basis, in the sense of being unfounded, or unjustified, or unsupported. Whereas, on my view, all views – good and bad – are in this important sense baseless, unfounded, unjustified, unsupported.)

In so far as my approach involves all this, my solution of the central problem of justification – as it has always been understood – is as unambiguously negative as that of any irrationalist or sceptic.

A key part of the issue is the problem situation:

How can we adjudicate or evaluate the far-reaching claims of competing theories and beliefs?

Justificationism is an answer to this problem. It answers: the theories and beliefs with more justification are better. Adjudicate in their favor.

This is not an inherently infallibilist answer. One could believe that his conception of which theories have how much justification is fallible, and still give this answer. One could believe that his adjudications are final, or one could believe that his adjudications could be overturned when new justifications are discovered. Infallibilism is not excluded nor required.

Looking at the big picture, there is the critical approach to evaluating ideas and the justificationist or “positive” approach.

In the Popperian critical approach, we use criticism to reject ideas. Criticism is the method of sorting out good and bad ideas. (Note that because this is the only approach that actually works, everyone does it whenever they think successfully, whether they realize it or not. It isn’t optional.) The ideas which survive criticism are the winners.

In the justificationist approach, rather than refuting ideas with negative criticism, we build them up with positive arguments. Ideas are supported with supporting evidence and arguments. The ones we’re able to support the most are the winners. (Note: this doesn’t work, no successful thinking works this way.)

These two rival approaches are very different and very important. It’s important to differentiate between them and to have words for them. This is why Popper named the justificationist approach, which had gone without a name because everyone took it for granted and didn’t realize it had rivals.

Both approaches are compatible with both infallibilism and fallibilism. They are metaphorically orthogonal to the issue of fallibility. In other words, fallibilism and justificationism are separate issues.

Fallibilism is about whether or not our evaluations of ideas should be subjected to revision and re-checking, or whether anything can be established with finality such thing we no longer have to consider arguments on the topic, whether they be critical or justifying arguments.

All four combinations are possible:

Infallible critical approach: you believe that once socialist criticisms convince you capitalism is false, no new arguments could ever overturn that.

Infallible justificationist approach: you believe that once socialist arguments establish the greatness of socialism, then no new arguments could ever overturn that.

Fallible critical approach: you believe that although you currently consider socialist criticisms of capitalism compelling, new arguments could change your mind.

Fallible justificationist approach: you believe that although you currently consider socialist justifying arguments compelling (at establishing the greatness and high status of the socialism, and therefore its superiority to less justified rivals), you are open to the possibility that there is a better system which could be argued for even more strongly and justified even more and better than socialism.

The big picture is that I don’t think trying to make sense of the details of what DD wrote is a good goal. Neither he nor anyone else is willing and able to explain and defend the specifics of what he wrote. It’s also important to avoid semantic quibbles and terminology confusions. The word “justify” has more than one meaning, so in epistemology discussions I normally try to use it to talk about only one thing: positive arguments. Instead of DD details or terminology, it’s better to focus on the subject matter of epistemology. If you understand and agree with:

  • rejecting infallibilism
  • rejecting positive arguments
  • rejecting partial arguments

then cool, I think that’s a good start on CR+CF. If you don’t understand or disagree with one or more of those then I think that’d be a good issue to put some attention on.

Do you mean this just in the context of justificationism? If someone was new to philosophy would you still recommend they read BoI?

All of our knowledge comes from guesses (conjecture). We can guess all kinds of explanations, that doesn’t imply they are correct. Our guesses could always be wrong (fallible). In order to have an “infallible” belief we would need some authoritative method which could justify knowledge as true. No such method has been proposed as far as I know.

It doesn’t make sense to say than an idea is true (or even likely true). Anytime we provide a reason for why we think something is true we have to relate it back to an authority of some kind. For example:

Theory X is true because I proved it with empirical evidence. (empirical evidence is being used as the authority)

Theory X is true because I did some Bayesian statistical analysis and got confirming result Y. (Bayesian statistical analysis is being used as the authority)

Theory X is true because it has survived criticism and was selected with rational argument (rational argument is being used as an authority)

Theory X is true because I read it in a holy book… and so on.

We should criticize ideas where we can and tentatively accept ideas that we can’t criticize.

I don’t know what you mean by partial argument. Is there a source where I could read more about this?

Thanks for any feedback.