Here is my position:

1). I cannot know false propositions a priori.
2). I can have known false propositions a posteriori.

This is because I cannot distinguish the truth from my beliefs a priori, and yet I do make the distinction in hindsight. My concept of truth is in flux, so there is no contradiction here, even if this position isn't compatible with common grammatical usage of the verb "to know" or "to have known".

↪Janus You prefer utility to truth?

Do you think you can maintain that distinction? The truth doesn't care about what is useful — Banno

But ‘caring’ seems to go along with truth. Pesky concepts like mattering , relevance and significance are baked in whenever we ‘use’ the word truth. And those words dont care about universal meaning abstracted away from contextual sense.

And?

. I cannot know false propositions a priori. — sime

What does it mean to know a false proposition?

Not sure how to read that. Are you saying that, a priori, we cannot know false propositions - that all the propositions we know are not false? Or are you saying that we cannot know a priori that some proposition is false? That seems wrong, since it seems we know a priori that "this triangle has four sides" is false.

Is your concept of truth in flux, or is the set of true propositions in flux?

If we know something is true we must know it is not false. That's not the same as that it cannot* be false. It's not knowledge that is defeasible, but belief. Everything we know is true - just like every fact is true. Some things we think we know, are false - and therefore we do not know them.

If we think we know it's true, but it turns out it is false, then we didn't know it was true in the first place.

See how it works?


*Are we going to look at modality again? Let's not. — Banno

You say that if we know something is true we must know it is not false. But is not knowing something is not false the same as knowing that it could not be false (aside from switching contexts or changes over time)? Was it something like the caveat in brackets that led to your mention of modality?

But is not knowing something is not false the same as knowing that it could not be false — Janus

Why the modality? Are you asking if ~K~p≡K~◇~p ? Well, no, since p does not have the same truth value as ☐p.

Drop the modal operator, do you have ~K~p≡Kp? That's also false. There are things we don't know we don't know and that's not the same as knowing those things.

If you indeed know that p, then p is true.

If you indeed know that p, then p is true. — Banno

Right, and if p is true then it cannot be false, no? Likewise if you know that p is true then you cannot know that it could be false, or so it would seem.

f p is true then it cannot be false — Janus

Sort the ambiguity. p⊃~~p, but not p⊃~◇~p.

If p is true then it is not false. But not, if p is true then it cannot be false.

Folk seem to think that if, if we know something then it is true, then we can never be mistaken.

Think on it a bit.

If we think we know something and it turns out to be false, then we didn't know it.

If we think we know something and it turns out to be false, then we didn't know it. — Banno

That's right. So, if we know p could be false, then we don't know that it's true, but we may well believe that it's true. Thinking we know something is not the same as knowing something.

Hm. — Janus

if we know p could be false, then we don't know that it's true — Janus

No. I know the cat is on the chair but it could have been on the mat. Hence "the cat is on the chair" is true but could have been false.

Thinking we know something is not the same as knowing something — Janus

Better to use "believe". Believing we know something is not the same as knowing something.

'cause amongst other things it needs also to be true.

No. I know the cat is on the chair but it could have been on the mat. Hence "the cat is on the chair" is true but could have been false. — Banno

Ah, I see the problem now, it seems we've been talking at cross purposes—"could have been false" is not equivalent to "could be false".

If you like. The ambiguity needed ironing out.

:up:

So, if we know p could be false, then we don't know that it's true — Janus

This is correct, and it is the crux. Someone like @J thinks that for every proposition or claim, we know that it could be false (and therefore we cannot know that any proposition is true). Put differently, @J thinks that every belief should include the caveat, "This could be false."

"Could have been" is a different question. You are asking the more central question, which is, "Could be false."

When Aristotle talks about this he basically talks about the possible alternatives, where the case where we know there are no possible alternatives is a case of proper knowledge. Thus if we know that something could be false then we do not have proper knowledge that it is true (scientia).

When do I ever know something is true apart from having the right justifications? — J

We know analytic statements are true. — Janus

But do we know this apart from the right justifications? I don't see how. Even something as clear as modus ponens can and must be explained and justified; we don't say "I just know it."

If we say, a person S knows that P when P is the case, they believe that P, and their belief that P is "justified," in whatever sense we give that word, then what S says or is entitled to say about their possible knowledge that P just doesn't enter into it — Srap Tasmaner

You're quite right. My use of "I can say" was loose talk, borrowed from a certain style of discussing these problems. More precisely: "what I can say" = "what I can think or believe to be correct or reasonable, and hence assertable in this sort of discourse." The actual saying or asserting isn't necessary, or even the point, as you show.

the difference between "P is true" and "I know that P is true".

These are not the same. — Banno

Right. As I wrote, above:

But JTB is not about what makes something true, but how I can say [see reply to Srap above] I know it to be true. The truth or falsity of the proposition under discussion remains what it is, no matter what I know or don't know. — J

But the T in JTB is dependent on P's being true, not on the circularity of your knowing that P is true.

Am I misunderstanding you in some way? You seem to miss this very obvious point. — Banno

Yes, I think we're a bit at cross-purposes here. The T in JTB is absolutely about something's being true. My question is about how we'd know it to be true. You seem to be saying that there's an independent way of determining whether X is true -- a pre-qualification, so to speak -- that will allow us to import the T into JTB, and then talk about our justifications. That's what I find confusing.

The entire question falls inside the scope of human activity, not ontology. Truth, as I know you firmly believe, is a property of propositions, not objects. If X is true, then X is a proposition. Yes, this proposition describes something else (fact, state of affairs, call it what you will), but that is a different matter. "The T in JTB is dependent on P's being true" -- yes, but if we don't ask "How can I know this?" then I don't understand how we'd ever be able to use T in JTB.

Having said all that, it's entirely possible that I've misunderstood you. :smile: So feel free to clarify.

A question remains though― what use is something's being true if we don't know it. — Janus

That's more or less what I'm wondering too, though I'd limit my wondering to the use of "true" in JTB.
I can conceive of other contexts for claiming that the concept of truth is useful, even if we don't know whether a given X is true.

Are you [@sime] saying that, a priori, we cannot know false propositions - that all the propositions we know are not false? — Banno

Yes, that's the right question, and returns us to the issues around JTB. JTB proposes that only true propositions can be known, AND that there is a way to determine truth apart from justifications. Crucial here is "determine truth," not "make X true." X will be true (or false) regardless of whether we can determine it to be so, but if we can't determine it to be so, how are we supposed to construct the T leg of JTB?

JTB proposes that only true propositions can be known, AND that there is a way to determine truth apart from justifications. — J

I don't think a JTB account is committed to this. You can, and I think this is quite common, simply be a realist (with whatever restriction). That is, it suffices for the proposition to be true or false, whether there is any way to determine its truth value or not.

If I justifiably believe that P, then if P is the case, I am in a state of knowledge that P, and if not then not. Whether anyone knows or can know that I know that P, is a separate issue.

↪Janus You prefer utility to truth?

Do you think you can maintain that distinction? The truth doesn't care about what is useful
— Banno

But ‘caring’ seems to go along with truth. Pesky concepts like mattering , relevance and significance are baked in whenever we ‘use’ the word truth. And those words dont care about universal meaning abstracted away from contextual sense — Joshs

↪Joshs And? — Banno

My point is that the word ‘truth’ doesn’t have any aspect of its meaning that transcends the context of its actual use. It’s not just that truth is affected by contextual relevance, it’s that there is no categorical meaning of the word ‘truth’ that exists outside of the grammar of its use. I’m not just saying that our access to truth is contextual, but that the very concept of truth is nothing over and above how we actually use the word "truth" in particular language games. There's no essence of truth waiting to be discovered, only the diverse ways we employ the concept in different contexts.

When you say “truth doesn't care about what is useful," you seem to be treating truth as something with its own independent nature. But this very statement only makes sense within a specific language game where we contrast truth with utility. The meaning isn't pointing to some metaphysical feature of truth itself, but emerges from how we've learned to use these concepts in opposition to each other. Our concepts don't get their meaning by corresponding to independent realities, but through their role in our forms of life. So "truth," "relevance," "significance", these aren't mapping onto features of the world so much as they're tools we use for various purposes in different contexts.

That is, it suffices for the proposition to be true or false, whether there is any way to determine its truth value or not. — Srap Tasmaner

But that's the part I find incoherent. Is the idea that P need only be truth-apt in order for "P is a JTB" to represent knowledge? That can't be right. We need to know if it's actually true. So if we can't determine T in some way independent of J, how are we supposed to use JTB as a test for knowledge? What is the criterion that allows us to import "T" into the formula, if we can't know whether X is T?

If I justifiably believe that P, then if P is the case, I am in a state of knowledge that P, and if not then not. — Srap Tasmaner

Yes (leaving aside the earlier questions about "good justifications"). But if JTB can't help us tell the difference between being in a state of knowledge that P, and not being in that state, what good is it?

if JTB can't help us tell the difference between being in a state of knowledge that P, and not being in that state, what good is it? — J

Indeed.

if we can't determine T in some way independent of J, how are we supposed to use JTB as a test for knowledge? — J

Apparently we can't.

Is that what JTB is for?

Take a step back. Is there any prospect for any kind of theory that would pick out all and only true propositions? That would in every case distinguish true beliefs from false ones — or even justified beliefs from unjustified beliefs?

I think we can be skeptical any such theory is possible, either on general grounds of human fallibility or even on logical grounds (the problem of the criterion),

So what are we about?

@Sam26 does seem to want to say, "My claim to know certain things is justified because I used a really good epistemology." I don't think it works that way.

"The T in JTB is dependent on P's being true" -- yes, but if we don't ask "How can I know this?" then I don't understand how we'd ever be able to use T in JTB. — J

Again, if you think the T in JTB can be known apart from the J and the B then you have rejected the JTB account. You have claimed that there is knowledge apart from J and B.

JTB proposes that only true propositions can be known, AND that there is a way to determine truth apart from justifications. — J

If JTB thought there were a way to know truth apart from justification, then there would be no J in JTB. You are effectively objecting to a 'T' account of knowledge, not a 'JTB' account of knowledge.

You are still doing your "JTB as a recipe for knowledge-cakes," noted from my very first post.

So if we can't determine T in some way independent of J, how are we supposed to use JTB as a test for knowledge? — J

JFB fails the test for knowledge, and we know P is F rather than T due to a "justification," namely a justification separate from the particular J in JFB. If someone offers a claim and we have no reason to believe it is false, then we cannot claim that it is false (i.e. not true).

You are always searching for a magic bullet that will allow us to get behind the scenes and infallibly distinguish JTB from JFB according to some "God's-eye view." There isn't one, but that doesn't mean JTB is incoherent.

(The trouble is that you hijack every epistemological discussion and make it about this pet question of yours, in much the same way that an atheist will hijack every theological discussion and make it about the existence of God.)

I think we can be skeptical any such theory is possible, either on general grounds of human fallibility or even on logical grounds (the problem of the criterion),

So what are we about? — Srap Tasmaner

Agreed. I'd be much more interested in a theory that could show how, in practice, we're able to make pretty good distinctions among degrees of likelihood, knowledge, certitude, etc. The case of analytic knowledge is perhaps special, but I won't open all that up in this context, since even a piece of analytic knowledge must have some justification.

I think JTB is intended as a test for knowledge, yes, not merely a description (to which no one has access!).

@Sam26 does seem to want to say, "My claim to know certain things is justified because I used a really good epistemology." I don't think it works that way. — Srap Tasmaner

Maybe not exactly, but I think Sam is nonetheless on the right track. We do know certain things, and we are justified in claiming we do, and without a really good epistemology (or epistemological practice), we'll make mistakes. I think a flexible JTB(+U) schema can help us understand how all this is possible. We just have to avoid some sort of essentialism or "definitionalism" (as @Banno has pointed out) about what counts as knowledge and justification. There are just too many uses, contexts, and practices.

how are we supposed to use JTB as a test for knowledge? — J

Is that what JTB is for? — Srap Tasmaner

What is JTB for?

It is not a "test" in the sense that we have a machine that allows us to practically run any knowledge-claim through it and know in fact whether it is or is not knowledge.

But it is at the very least supposed to provide a set of three necessary and sufficient conditions for knowledge.

@J's objection could be that the T in JTB is otiose, but this is obviously false. The objection could also be premised on the idea that JTB is a kind of automatic knowledge-testing machine and that J, T, and B are three separate and reliably verifiable properties of every knowledge-claim. This is also false, as is the sub-idea that the three properties are supposed to be separable: as if we could have knowledge of each of them separate from the others.

JTB is a tripartite schema, which means that the three components are not separable vis-a-vis knowledge. Beyond that, every epistemological approach will fail to provide a knowledge-guarantee-machine. If one is looking for a knowledge-guarantee-machine, then it is not only JTB that will let them down.

Folk seem to think that if, if we know something then it is true, then we can never be mistaken.

Think on it a bit.

If we think we know something and it turns out to be false, then we didn't know it. — Banno

That seems accurate. But so does this:

[it is false that] J, T, and B are three separate and reliably verifiable properties of every knowledge-claim. This is also false, as is the sub-idea that the three properties are supposed to be separable: as if we could have knowledge of each of them separate from the others.

JTB is a tripartite schema, which means that the three components are not separable vis-a-vis knowledge. — Leontiskos

I agree with Leon, but then, because of the possibility of error, what is happening when we think we know something but we do not? Wouldn’t we have to be able to separate J, T or B from the others to think we know something when in fact what we know is missing J, T or B? Or are all three destroyed, along with K, when we are in error?

I agree with Leon, but then, because of the possibility of error, what is happening when we think we know something but we do not? Wouldn’t we have to be able to separate J, T or B from the others to think we know something when in fact what we know is missing J, T or B? Or are all three destroyed, along with K, when we are in error? — Fire Ologist

I think the first thing is this:

JFB fails the test for knowledge, and we know P is F rather than T due to a "justification," namely a justification separate from the particular J in JFB. If someone offers a claim and we have no reason to believe it is false, then we cannot claim that it is false (i.e. not true). — Leontiskos

So on JTB we will only know we have failed when we know that one of the three conditions is absent. And we cannot know that T is absent unless we know that the knowledge-claim is not true. And we cannot know that the knowledge-claim is not true if we are not justified in so knowing, which means that we must have reasons or grounds (whether or not we can articulate them). More simply, it means that knowledge-claims are never invalidated except in light of some other, opposed knowledge-claim. So contrary to @J's thinking, one would never know or even claim that T is absent without reasoning/justification.

This means that if John claims that Ben's knowledge-claim is false, there is the presupposition that John's claim involves JTB. John believes Ben's knowledge-claim is false; it is true that Ben's knowledge-claim is false; and Ben has the proper justification for knowing that Ben's knowledge-claim is false. Nowhere arises the idea that John must know whether Ben's knowledge-claim is true or false apart from justification (or belief, for that matter).

Or are all three destroyed, along with K, when we are in error? — Fire Ologist

I don't see how belief would be destroyed, but there is at least one sense in which justification and truth rise or fall together. But that gets us back to @Sam26's questions about Gettier's objection.

My question is about how we'd know it to be true. — J

JTB sets out criteria for a sentence to count as knowledge. It is not a method for determining the truth of some sentence.

You seem to be saying that there's an independent way of determining whether X is true — J

That the sentence is true is one of the criteria for the sentence being known. This says nothing aobut how we determined if the sentence is true.

JTB proposes that only true propositions can be known, AND that there is a way to determine truth apart from justifications. — J

I don't agree with the second part of this. There is a difference between a sentence being true and a sentence being determined as true. You again seem to conflate these. There is a difference between "P is true" and "J determined that P is true". JTB specifies that the sentence must be true, not that the sentence must be "determined to be true".

This seems to me to be the source of your confusion.

I don't think a JTB account is committed to this. — Srap Tasmaner

Yep.

I think JTB is intended as a test for knowledge, yes, not merely a description — J

Well, maybe not. Perhaps it's just about the grammar of the use of the term "know" - that we use the term for sentences that are justified, true and believed, and that a use contrary to these would be infelicitous. It's not a method for determining which sentences are true and which are not - which is what you seem to want it to be.

You seem to have an image of an investigator looking at a sentence and saying "ok, Criteria one: I believe this sentence; criteria two: this sentence is justified by such-and-such; but criteria three: how can I decide if the sentence is true?" But that's not how the idea would be used - there's an obvious circularity in such a method, surely. If you believe the sentence (criteria one), then you already think it to be true and criteria three is irrelevant.

My point is that the word ‘truth’ doesn’t have any aspect of its meaning that transcends the context of its actual use. — Joshs

Do you see this as something with which might disagree, or which is incompatible with what has been said?

When you say “truth doesn't care about what is useful," you seem to be treating truth as something with its own independent nature. — Joshs

Not at all.

So "truth," "relevance," "significance", these aren't mapping onto features of the world so much as they're tools we use for various purposes in different contexts. — Joshs

How can they be tools if they do not in some way "map" onto the world?

JTB sets out criteria for a sentence to count as knowledge. It is not a method for determining the truth of some sentence. — Banno

That's right. So, anticipating your investigator image, using JTB would go something like this:

Q1. Do I have knowledge of X (a proposition)? Depends on . . .
Q1a. Do I believe X?
Q1b. Can I justify my belief in X?
Q1c. Is X true?

Q1b is problematic, as we've noted, but let's allow that we understand what a "good enough justification" would look like. So we can go down the list:

Q1a. Yes.
Q1b. Yes.
Q1c. ????

What can we say about Q1c that doesn't involve an appeal to knowledge? We want to say, Yes, X is true. But we would have to know that, just as we know the first two answers, and we can't, because that begins the vicious circle.

I think what you're suggesting is that instead we should say, "I don't know if X is true. Such knowledge is impossible without circularity. But if it's true, then I know X. And if it isn't, then I don't." So, as you say, a strictly descriptive or criteriological formulation. However, I maintain that this is not only useless, but contrary to the spirit of JTB. JTB is supposed to help us evaluate knowledge claims -- keep us epistemologically honest. And on this construal, it can't.

That the sentence is true is one of the criteria for the sentence being known. This says nothing about how we determined if the sentence is true. — Banno

That's right. But then what should we use JTB for?

There is a difference between "P is true" and "J determined that P is true". JTB specifies that the sentence must be true, not that the sentence must be "determined to be true".

This seems to me to be the source of your confusion. — Banno

Well, I think it's JTB that's confused, not me. Because as I said to @Srap Tasmaner, what use is JTB if it can't show us how to tell whether we know something or not? Being told, "Well, you would know it, if it was true" is pretty thin gruel and, as I said, not to the purpose of JTB as I understand it.

You seem to have an image of an investigator looking at a sentence and saying "ok, Criteria one: I believe this sentence; criteria two: this sentence is justified by such-and-such; but criteria three: how can I decide if the sentence is true?" But that's not how the idea would be used - there's an obvious circularity in such a method, surely. If you believe the sentence (criteria one), then you already think it to be true and criteria three is irrelevant. — Banno

Good, this is a helpful image. And if we set it up like this, then it's another way of showing how JTB is faulty. Because it's absolutely right that the T criterion becomes irrelevant; that's what I've been arguing, using a different approach, all along. I would emphasize the justifications rather than the belief, but it comes to the same thing.

I don't see how belief would be destroyed, but there is at least one sense in which justification and truth rise or fall together. But that gets us back to Sam26's questions about Gettier's objection. — Leontiskos

You are right that there is at least one sense in which justification and truth rise or fall together. But Gettier's argument assumes that they do not, that is, that it is possible to be justified in believing that p and for p to be false. In that case, the link between JTB and knowledge rests entirely on the T clause. But if I'm evaluating whether someone knows that p, I must make my own evaluation of the truth or falsity of p, which re-introduces the entire process.

That the sentence is true is one of the criteria for the sentence being known. This says nothing about how we determined if the sentence is true. — Banno

I agree with you. But does that mean that the definition must take the truth or falsity of the sentence as given, in some way?

You seem to have an image of an investigator looking at a sentence and saying "ok, Criteria one: I believe this sentence; criteria two: this sentence is justified by such-and-such; but criteria three: how can I decide if the sentence is true?" But that's not how the idea would be used - there's an obvious circularity in such a method, surely. If you believe the sentence (criteria one), then you already think it to be true and criteria three is irrelevant. — Banno

Considering the process of applying the definition is interesting. I don't often see it raised. It seems just obvious to me that it must be my evaluation of the knower's justification (NOT my justification), my evaluation of the truth, and the knower's belief. That means, IMO, that I have to take a position on whether the sentence is true or not. This has the awkward consequence that I can never learn anything from anyone else. That seems to make the concept of knowledge a bit limited and rules out the possibility of standing on anyone's shoulders, giant or not.