I was reading the IEP's article on epistemic justification, and came across the following paragraph(s):

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I'm having a hard time with the sentence "Proposition 3 is not justified unless Propositions 1 and 2 are justified." Why is this true? If we accept the rule "After a person sees that X, they are justified in believing X," then I am justified in believing (3), regardless of whether I am justified in believing (1) and (2). In other words, if some set of facts makes me justified in believing (3), why must these facts take the form "I am justified in believing..."?

I have come to the following, slightly strange understanding which may well need correction. When a person sees the cat on the mat, they are justified in believing there is a cat on the mat. When a person tries to justify their belief that they are justified in believing there is a cat on the mat, they must justify their belief in the set of facts which would imply they are justified in believing there is a cat on the mat. It is while doing this that they must justify (1) and (2). On this interpretation, "I am justified in believing (3)" only requires "I see a cat on the mat". The claim "I am justified in believing that I am justified in believing (3)" requires "I am justified in believing (1) and (2)".

Edit: A commenter has pointed out that one can be justified in believing something false, and unjustified in believing something true, so that a claim being true and its being justified are logically independent. This is exactly the reason why I'm confused. The facts about S which make S justified in believing (3) could be facts like "S sees a cat on the mat," instead of "S is justified in believing S sees a cat on the mat." In this case, whether or not S is justified in believing that S sees a cat on the mat is immaterial. S is under no obligation to show that S is justified in believing S sees a cat on the mat; S has an obligation to show that S sees a cat is on the mat.

  • 1
    In justification logic, one class of solutions to this problem is to say that justification sentences themselves can be given "ex officio," as initial justifications, including as self-justifiers. This is close to the intent behind the phrase "self-evident." You seem to be on the right track, anyway... Nov 12, 2023 at 2:30
  • I guess my question is why there is a problem/regress at all. "I am justified in believing (3)" does not seem to require "I am justified in believing (1) and (2)". It seems only to require that (1) and (2) are true.
    – sidkol
    Nov 12, 2023 at 6:15
  • 2
    Adopting the rule "after a person sees that X, they are justified in believing X" is unadvisable. Persons "see" a lot of illusions and hallucinations. One may want to replace (1) and (2) with something more suitable, but dropping them without replacement is not viable.
    – Conifold
    Nov 12, 2023 at 7:31
  • The point of the paragraph is simply to state that one must justify each supposedly good reason. So, one must justify both 1) and 2) in order to justify 3). But supposedly, 1) and 2) will also have reasons for justification that themselves need to be justified. This leads to a regress. Nov 12, 2023 at 16:26
  • If I understand correctly, you're saying that belief in (3) is justified only if belief in (1) and (2) are justified. But why? Change (2) to say "seeing that X implies belief in X is justified" (the statement in the paragraph is untenable in its literal form). Then, as long as (1) and (2) are true, I am justified in believing (3). So (1) and (2) need to be true, not justified.
    – sidkol
    Nov 12, 2023 at 17:20

1 Answer 1


Let me see if I understand you correctly. You are saying:

A. Whether a person is justified in holding a belief X is a question of whether they have sufficient evidence that directly supports X.

B. Whether a person is justified in believing, "I am justified in believing X," is a question of whether they can trace back their justifications for X multiple steps to a more fundamental level, justifying their justifications and so on.

In colloquial usage there is nothing wrong with (A), and also (B) is fine, considered independently. The basic difficulty is that what it means to "justify" something is ambiguous.

It's ambiguous because, like many questions of terminology in relation to common-sense reasoning, it's a matter of degree. A belief could be well-justified, meaning that we can trace back the support for the belief back to things that seem very basic and certain. Or a belief could be poorly-justified, meaning that the argument supporting the belief is shallow and based on unsteady premises or involving uncertain inferential leaps. Or anywhere in between.

"I saw a cat" does indeed justifiably support the belief that a cat was there. But how much does it support it? Fairly well, in most cases. But not perfectly. Sometimes our eyes can be fooled. So to justify it better, we might trace back more steps - how do you really know what you saw was a cat? Maybe it was a pile of clothes in the dark you only thought was a cat. That's happened to me. But we could eliminate that by pointing out that it was not dark where you were looking, and you could make out fine features of the cat. That would be stronger justification. But maybe it was only a sculpture of a sleeping cat. Maybe it was a hallucination. There is always some doubt, which leaves room for additional justification (as long as you have more evidence to add).

That section of the IEP article is talking about a rather strong and absolute degree of justification, according to which nothing is justified unless you have a good reason for it, that reason also being justified. This leads to infinite regress, and actually they are only talking about this absolute degree of justification for the purpose of poking holes in it. They go on to describe lesser notions of justification, such as where the infinite regress terminates in basic beliefs.

Even allowing the regress to terminate in basic beliefs is a stronger notion of justification than what you are talking about. But your notion is okay too - as long as you make it clear you are only talking about a lesser, immediate degree of justification.

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