If you think that the person did not commit the crime, then you believe that the conclusion that they did commit the crime is unjustified. — Metaphysician Undercover

A conclusion is justified if there's evidence for it. There's evidence for it; therefore, it's justified.

But if you thought that it was just an opinion, and other people might have contrary opinions which were reasonable, you wouldn't designate the belief as false. A false belief is not a reasonable opinion. — Metaphysician Undercover

An opinion can be reasonable but false, so I would designate the belief as false.

Example: both believing in God and not believing in God are reasonable and justified beliefs and there exist valid arguments for both. I still have an opinion on that that I believe to be objectively true, but still objectively recognize as a subjective opinion.

If you believe that X was a justified belief, but is no longer a justified belief, then it is still a lie if you state "X is a justified belief". — Metaphysician Undercover

Yes but you could say it was a reasonable belief. It was justified to believe the Earth was justified in the medieval times.

A conclusion is justified if there's evidence for it. There's evidence for it; therefore, it's justified. — Michael

That's not true, evidence supports a theory, it doesn't necessarily justify the conclusion. It is false to say that any time there is evidence for a particular conclusion, then that conclusion is justified. The evidence must be conclusive. And if the evidence is conclusive then falsity of that which is justified, is ruled out, in the mind of the one making the conclusion.

An opinion can be reasonable but false, so I would designate the belief as false.

Example: both believing in God and not believing in God are reasonable and justified beliefs and there exist valid arguments for both. I still have an opinion on that that I believe to be objectively true, but still objectively recognize as a subjective opinion. — BlueBanana

If you are considering both options, to believe in God, and to not believe in God, then you allow that one of these is false, but you are not believing that a particular one of them is false.

Yes but you could say it was a reasonable belief. It was justified to believe the Earth was justified in the medieval times. — BlueBanana

You could say that it "was" a justified belief, but notice that (1) in the op requires that it "is" a justified belief. Because knowledge is said to be justified true belief, we are not concerned with belief which was justified, but no longer is.

The evidence must be conclusive. — Metaphysician Undercover

So, like BlueBanana, you're saying that a belief is only justified if it's certain? Then I'll repost what I said to him:

If I meet someone and she tells me that her name is Sarah then I'm not justified in believing that her name is Sarah because it isn't certain – she might be lying? And even if she shows me her passport and driving license then I'm still not justified because it still isn't certain – they might be forgeries?

Requiring certainty for justification seems unreasonable.

If I meet someone and she tells me that her name is Sarah then I'm not justified in believing that her name is Sarah because it isn't certain – she might be lying? And even if she shows me her passport and driving license then I'm still not justified because it still isn't certain – they might be forgeries? — Michael

I don't see the relevance. Showing her id. seems like conclusive evidence to me, so you'd be justified in believing her name is Sarah. The point I made is that not just any piece of evidence serves to justify.

Requiring certainty for justification seems unreasonable. — Michael

I agree with this. What I don't agree with is the idea that one could think "her name is Sarah" is both a justified belief and also false. So after checking her id, you honestly believe that her claim to be Sarah is justified, but you also honestly believe it to be false.

I don't see the relevance. Showing her id. seems like conclusive evidence to me, so you'd be justified in believing her name is Sarah. The point I made is that not just any piece of evidence serves to justify. — Metaphysician Undercover

It's conclusive evidence even though it might be a forgery?

If you believe it to be a forgery then you do not believe it to be conclusive evidence. This is irrelevant to my point, which is that you cannot believe it to be false (a forgery), and justified at the same time.

This is irrelevant to my point, which is that you cannot believe it to be false (a forgery), and justified at the same time. — Metaphysician Undercover

Sure I can. If Sarah shows you her ID then your belief that her name is Sarah is justified. However, being that she's my sister and that she's showing you an ID that I forged then I know that your belief is false.

You're conflating my belief with your belief. The point is that the same person cannot hold these two beliefs. That's what is stated in the op.

You're conflating my belief with your belief. — Metaphysician Undercover

I'm not. I believe that your belief is justified and I believe that your belief is false. So I believe that your belief is both justified and false.

I don't believe that you believe my belief is justified. You know that the documents are falsified so you know that my belief is not justified, and you are lying by telling me that you think my belief is justified. it's called "deception".

I don't believe that you believe my belief is justified. You know that the documents are falsified so you know that my belief is not justified, and you are lying by telling me that you think my belief is justified. it's called "deception". — Metaphysician Undercover

It doesn't matter that I know that they're forgeries. Whether or not your belief is justified depends on whether or not the evidence available to you is compelling, which you admitted it is. You said that her ID is conclusive evidence.

It would be unreasonable for me to believe that her name is Sarah, but it doesn't then follow that it would be unreasonable for you to believe that her name is Sarah.

To make this clearer, consider you were accused of having sex with a 15 year old (and the age of consent is 16). You tell the judge that she showed you her ID and that it said she was 16. Would it be right for the judge to counter by claiming that he knows that it's a fake ID, and so that your belief that she was 16 wasn't justified – that you're guilty? Of course not. The judge will say that although your belief was false it was justified, and so you're innocent.

Whether or not your belief is justified depends on whether or not the evidence available to you is compelling, which you admitted it is. — Michael

I think that's a very strange definition of "justified". If we go with "compelling evidence" as you suggest, then justification cannot be, as you suggest, a matter of the evidence being compelling to me, or else all my beliefs would be justified, because I only believe something when the evidence compels me to believe.. This would be a completely subjective Justification and justification is meant to bring objectivity to the belief. Therefore justification cannot be defined as "compelling to me", or "compelling to you", it requires more than this. So your claim, rather than being a lie, is just based in a misunderstanding of what it means to be "justified".

If you are considering both options, to believe in God, and to not believe in God, then you allow that one of these is false, but you are not believing that a particular one of them is false. — Metaphysician Undercover

I'm not considering them both, I accept both as justified beliefs.

You could say that it "was" a justified belief, but notice that (1) in the op requires that it "is" a justified belief. — Metaphysician Undercover

How does it matter what time we're talking about? Does it change with time whether a false belief can be justified? If we were having this discussion in the medieval times, it'd have clearly been possible to have a justified false belief.

Then "compelling" might not be the right word. But my point stands with the example of you being accused of having sex with someone underage. It would be entirely appropriate for the judge to accept that your belief that she was 16, although false, was justified, and so to find you innocent of the charge.

A conclusion is justified if there's evidence for it. There's evidence for it; therefore, it's justified. — Michael

A foundationalist would probably disagree with this...it would also rule out all forms of a priori knowledge, it seems to me, as I generally associate "evidence" with empirical modes of investigation.

A foundationalist would probably disagree with this...it would also rule out all forms of a priori knowledge, it seems to me, as I generally associate "evidence" with empirical modes of investigation. — Arkady

"if", not "if and only if". ;)

I'm not considering them both, I accept both as justified beliefs. — BlueBanana

So you have contradictory justified beliefs then. "God exists" and "God does not exist" are both justified. I think that an individual would necessarily be lying to claim them both as justified.

How does it matter what time we're talking about? Does it change with time whether a false belief can be justified? If we were having this discussion in the medieval times, it'd have clearly been possible to have a justified false belief. — BlueBanana

Things change. We're discussing predication, whether "justified" mat be predicated of a specific belief. In all matters of predication, time is important due to the reality of change.

And we're not discussing whether a false belief can be justified, we're discussing whether one can believe that a belief is both false and justified.

Then "compelling" might not be the right word. But my point stands with the example of you being accused of having sex with someone underage. It would be entirely appropriate for the judge to accept that your belief that she was 16, although false, was justified, and so to find you innocent of the charge. — Michael

I don't agree, because there is a difference between being held not liable, and being justified. Being found not liable is not the same as being justified. To be justified is to be demonstrated as being right. To be not liable is to be demonstrated as being not legally responsible for something which is wrong. One involves rightness, the other wrongness.

So the judge would not say that the man was "justified" meaning "right" in having sex with someone underage, just because she showed him false id. The false id. might be considered as a mitigating factor, but it cannot negate the fact that the act itself was wrong. The judge might leave the man as unpunished, but that does not mean that the judge thinks that the man was justified (right) in committing the wrongful act. This would be contradictory, to say that the act (sex with a girl under 16) is a wrongful act, and also that the man was justified (right) in committing it. And this is evident in drinking establishments which get their licenses revoked for serving alcohol to minors even though the minors were using false id.

I don't agree, because there is a difference between being held not liable, and being justified. Being found not liable is not the same as being justified. To be justified is to be demonstrated as being right. To be not liable is to be demonstrated as being not legally responsible for something which is wrong. One involves rightness, the other wrongness.

So the judge would not say that the man was "justified" meaning "right" in having sex with someone underage, just because she showed him false id. The false id. might be considered as a mitigating factor, but it cannot negate the fact that the act itself was wrong. The judge might leave the man as unpunished, but that does not mean that the judge thinks that the man was justified (right) in committing the wrongful act. This would be contradictory, to say that the act (sex with a girl under 16) is a wrongful act, and also that the man was justified (right) in committing it. And this is evident in drinking establishments which get their licenses revoked for serving alcohol to minors even though the minors were using false id. — Metaphysician Undercover

I'm not saying that the man was right to have sex with the girl. I'm saying that the man was justified in believing that she was 16, given the evidence available to him.

If we look at an actual example, the law states that a person commits an offence if "B is under 16 and A does not reasonably believe that B is 16 or over". The law recognises that one can reasonably believe that someone is 16 even if they're not; the law recognises that one can have a justified false belief. And this isn't just some technicality of the law, but common everyday understanding.

I'm not saying that the man was right to have sex with the girl. I'm saying that the man was justified in believing that she was 16, given the evidence available to him. — Michael

Clearly he wasn't right in believing that she was sixteen, so he wasn't justified in believing that she was sixteen. Justification requires demonstrating that one is right.

And we're not discussing whether a false belief can be justified, we're discussing whether one can believe that a belief is both false and justified. — Metaphysician Undercover

If a belief is false, then one could believe that belief to be false. Yet, if the belief is justified, one can also believe it to be justified.

So you have contradictory justified beliefs then. — Metaphysician Undercover

Yes, unless you mean belief as in believing it. Contradictory justified beliefs exist, but one can't have contradictory justified beliefs.

Actually, I'm taking that back: one can have contradictory beliefs, but one can't have beliefs they believe to be contradictory.

If a belief is false, then one could believe that belief to be false. Yet, if the belief is justified, one can also believe it to be justified. — BlueBanana

So how could one believe the same belief to be both justified and false?

Clearly he wasn't right in believing that she was sixteen, so he wasn't justified in believing that she was sixteen. Justification requires demonstrating that one is right. — Metaphysician Undercover

You're equivocating. His belief was incorrect, but given the evidence was reasonable. A reasonable belief is a justified belief. A belief doesn't have to be correct to be reasonable, and so doesn't have to be true to be justified.

So how could one believe the same belief to be both justified and false? — Metaphysician Undercover

Why not? For example, when a belief has sufficient evidence it's justified, but if two equally valid conclusions can be drawn from evidence, one could say that the other conclusion is valid and basing one's beliefs in it would be justified, while believing the other conclusion but recognizing the choice of conclusion as subjective.

I'm not equivocating, because I've already said that your definition of "justified" is unacceptable. We ought to adhere to an acceptable definition of 'justified". If you check your dictionary you'll find that "justify" requires demonstrating the correctness of.

I wonder if I can tie this discussion back to the false knowledge, that was some interesting stuff back there.

I'm not equivocating, because I've already said that your definition of "justified" is unacceptable. We ought to adhere to an acceptable definition of 'justified". If you check your dictionary you'll find that "justify" requires demonstrating the correctness of. — Metaphysician Undercover

https://en.oxforddictionaries.com/definition/justified

1. Having, done for, or marked by a good or legitimate reason.

A belief is justified if there are legitimate reasons to believe it. Someone's ID showing them to be 16 provides you with legitimate reasons to believe that they are 16.

So you are justified in believing that they are 16, even if unbeknownst to you it's a fake and that they're 15.

"Justified" just doesn't mean "certain".

I agree that "justified" does not mean certain. However, demonstrating that a belief is "not wrong", does not demonstrate that it is correct. Nor does it demonstrate "good legitimate reason" to believe it. Therefore I reject your argument which assumes that demonstrating a belief to be "not wrong" qualifies as justifying that belief.

A justified true belief is true knowledge. It seems logical that justified belief is then knowledge. Knowledge can be false. Therefore a justified belief can be false. If something can be some way, I don't see why one couldn't believe the thing to be so. So, a justified belief can be false, and therefore one can believe a justified belief to be false.

Seems far fetched but that might work :chin: