I think JTB is intended as a test for knowledge — J

I think it's just meant to express what we mean by know, especially if we're knowledge internalists, which means we believe knowledge requires access to justification. A knowledge externalist doesn't require that.

So if we say Bill knows that Carrie was written by Stephen King, it's implied that the proposition is true. We aren't worried about how we know it's true.

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? — Ludwig V

Given that we believe the sentence, we believe that it is true. Do you mean more than that?

It's not enough, for the sentence to be known, that we believe it to be true. It must also be true.

...my evaluation... — Ludwig V

Our evaluation might be better.

Okay, suppose that we took JTB as a criteria for interpreting the use of the word "knowledge". So we have Jim over there who says that he knows a certain sentence to be true, and we wish to determine if he is using "I know that..." correctly. First, does Jim believe the sentence? Second is the sentence actually true? Third, does Jim have some justification for his belief? If any of these fail then we can conclude that his use of "I know that..." is problematic, and how.

Q1a. Yes.
Q1b. Yes.
Q1c.Yes - follows from Q1a: if you believe it, you believe it to be true.

But if we are considering Jim's case, not your own, then it is open to us to say that while Jim believes the sentence is true, we do not, and so Q1c is false, and presumably conclude that Jim does not know what he claims.

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. — Ludwig V

Well, I think Gettier creates a strange division between justification and truth, but the Gettier cases I am familiar with involve a proposition that is true, not false.

But if I'm evaluating whether someone knows that p, I must make my own evaluation of the truth or falsity of p, — Ludwig V

Yes, quite right.

This has the awkward consequence that I can never learn anything from anyone else. — Ludwig V

Why think that?

---

Q1. Do I have knowledge of X (a proposition)? — J

Again, that's not what JTB is for. It doesn't give you a recipe for knowledge, and it is not primarily meant to allow you to see if your own beliefs constitute knowledge. If one thought that JTB was meant to allow you to see if your own beliefs constitute knowledge, then the T and the B would be otiose, as you keep saying.

what use is JTB if it can't show us how to tell whether we know something or not? — J

Right, because if something can't show us how to answer your pet question then it must be of no use at all. :roll:

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." — J

No. We do have knowledge - we know things.

JTB is supposed to help us evaluate knowledge claims -- keep us epistemologically honest. And on this construal, it can't. — J

It doesn't tell us if they are true or not, so much as if they are known or not.

what use is JTB if it can't show us how to tell whether we know something or not? — J

Above, it told us that Jim was mistaken. He claimed to know something that was not true.

:up:

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

As I said earlier, knowing we are justified in believing that some purported piece of propositional knowledge is true, and that we can thus be said to know it is true, also involves knowing that are other things apart from the piece of purported propositional knowledge are true.

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." — J

If something is true by definition or if something is logically self-evident, or if the proposition concerns something being directly observed, then I would say we need no further justification.

If something is true by definition or if something is logically self-evident, or if the proposition concerns something being directly observed, then I would say we need no further justification. — Janus

I agree. But all three of these things -- truth by definition, logical self-evidence, and the reliability of direct observation -- are ways of demonstrating justification. To understand this, imagine explaining any one of them to an intelligent child. They all involve steps, cogitation, judgment, insight. We don't simply see why they are true, or at least not usually. In fact, as you know, the reliability of direct observation can be challenged, and the challenge is precisely for a justification as to how such observations lead to truth.

But all three of these things -- truth by definition, logical self-evidence, and the reliability of direct observation -- are ways of demonstrating justification. To understand this, imagine explaining any one of them to an intelligent child. They all involve steps, cogitation, judgment, insight. We don't simply see why they are true, or at least not usually. In fact, as you know, the reliability of direct observation can be challenged, and the challenge is precisely for a justification as to how such observations lead to truth. — J

I think life itself teaches us to trust our observations―animals do, so why shouldn't we? You are right that understanding definitions and logical self-evidence are taught, but all such teachings rely on the capacity of the student to "get it", which I think shows that the truth of things which are true by definition and logical self-evidence is simply obvious, and just needs to be pointed out to be established in conscious understanding.

Direct observation is challenged only by what I think of as trivial and ridiculous "mind in a vat", Evil Demon" or "you might be dreaming" scenarios, and I don't think those are to be taken seriously. That's why I say that what we know we know certainly, but only within contexts, not absolutely certainly.

Logical possibility allows any knowledge whatsoever to be subjected to radical skepticism, but I don't see a need to concern ourselves with such vacuous considerations.

This is yet another thing from the prolific David Lewis, contextualism, the short version of which used to be that we do know things in everyday life that we don't know in the philosophy seminar room.

So, does Bertrand Russell's famous turkey, who knows from a whole lifetime of experience that every morning—without fail—the nice man comes to feed him, also know that it is about to be fed when it sees the nice man coming to his pen on Thanksgiving morning?

I'm good with all that. Just wanted to make the case that almost anything we claim to be true requires some (potential) justification.

Well, I think Gettier creates a strange division between justification and truth, but the Gettier cases I am familiar with involve a proposition that is true, not false. — Leontiskos

It's not all that strange. A standard use of "justify" does indeed assume that if P is false, then there is no justification for believing that p. But this has the consequence that I can only be said to know P if I have a conclusive justification for P. That means that I do not know, for example, that the earth goes round the sun. So that definition can be said to be too strong. So many people believe we should relax the criterion and allow that I do know that the earth goes round the sun, even though I only believe it on authority. It is tempting to say that it follows that I can be justified in believing something even though it is false and Gettier explicitly says that is his assumption.

First, in that sense of "justified" in which S's being justified in believing P is a necessary condition of S's knowing that P, it is possible for a person to be justified in believing a proposition that is in fact false. — Analysis. vol. 23 (1966)

There's a wrinkle here that Gettier does not mention. It is clearly wrong to believe something that is known to be false and conclusive proof over-rides any non-conclusive justification. But where there is no conclusive evidence, one has to go with the evidence one has, and that does mean that one can be justified in believing something that turns out later to be false. That's a weakness in most of the cases. However, most people seem to go along with his (unstated) assumption that we must continue to call him justified when we know, but he does not, that his belief that Jones will get the job is false.

The proposition in question, in his first case, is

(e) The man who will get the job has ten coins in his pocket. — Analysis. vol. 23 (1966)

Smith wrongly, but not without justification, believes that Jones is the man who will get the job, but the truth is that Smith will get the job. So Smith is using "the man who will get the job" to refer to Jones, but we (and Gettier) are using it to refer to Smith. That makes two different statements expressed in the same words. There is no problem. (This solution does not apply to all Gettier cases).

This has the awkward consequence that I can never learn anything from anyone else.
— Ludwig V
Why think that? — Leontiskos

JTB requires me to accept a claim to knowledge only if I know it is justified and true (and believed). But that means that I have to know p as well as the person claiming knowledge.

This is yet another thing from the prolific David Lewis, contextualism, the short version of which used to be that we do know things in everyday life that we don't know in the philosophy seminar room. — Srap Tasmaner

That's not an unreasonable idea. Nonetheless, if it turns out that we are wrong, we are expected to withdraw the claim to knowledge. I may be said to know that my car will be safe in the car park, and that may be well justified. But it is is stolen, I have to admit that I was wrong.

the truth of things which are true by definition and logical self-evidence is simply obvious, and just needs to be pointed out to be established in conscious understanding. — Janus

It is obvious to us. But we have learnt how to do reasoning as part of learning language and interacting with people.

It's not enough, for the sentence to be known, that we believe it to be true. It must also be true. — Banno

What bothers me is the interface between belief and reality. "It must be true" is the something more that is required. But once I have assessed the evidence, what more could there be? so I have difficulty in seeing what this amounts to. The best I can come up with is that claims to knowledge, like any other claim, have to be withdrawn if they turn out to be false. There may be cases in which the truth or otherwise of the proposition in question is finally and conclusively determined, but most of the everyday stuff doesn't come up to that standard. So the caution remains in place.

"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? — Banno

They’re not tools for mapping onto objects, but for enacting new forms of sense in our material and discursive interactions with the world. A hammer doesn’t “map” onto nails. Its usefulness lies in how we employ it to drive nails.Truth is a tool that in some contexts we use to check agreement with facts. In other contexts, we use it to contrast honesty vs lying; in others, to resolve disputes. In addition to the sense of truth as empirical/factual, one can think of grammatical/conceptual truth, performative/expressive truth, aesthetic/evaluative truth, narrative/interpretive truth and many other senses of meaning of that ‘same’ word.

Wittgenstein would emphasize that these aren't competing theories of truth but different tools serving different purposes in our linguistic practices. The mistake is assuming all these uses must share some common essence.​​​​​​​​​​​​​​​​ There’s no one metaphysical object “truth” that the word latches onto.

Q1a. Yes.
Q1b. Yes.
Q1c.Yes - follows from Q1a: if you believe it, you believe it to be true. — Banno

But Q1c was not about belief, but rather truth. Yes, it follows from believing something that I also believe it to be true, but that's not a reply to Q1c, which asks "Is it true?" Nothing I believe can supply the answer; it depends on the facts.

JTB is supposed to help us evaluate knowledge claims -- keep us epistemologically honest. And on this construal, it can't.
— J
It doesn't tell us if they are true or not, so much as if they are known or not. — Banno

That's what I don't see how to separate. We both agree that only true things can be known. So if JTB tells us that X is known, it must also tell us at the same time that X is true.

Smith wrongly, but not without justification, believes that Jones is the man who will get the job, but the truth is that Smith will get the job. So Smith is using "the man who will get the job" to refer to Jones, but we (and Gettier) are using it to refer to Smith. — Ludwig V

Okay, that is an interesting way to approach the problem. The reason I don't think it works is because if Smith were using "the man who will get the job" to refer to Jones, then there would not be an entailment involved. In that case rather than there being an entailment, Smith's two propositions would just be saying the same thing with different words. But Gettier is explicit that an entailment is involved ("Let us suppose that Smith sees the entailment from (d) to (e), and accepts (e) on the grounds of (d)"), therefore what is at stake is not a mere matter of reference.

JTB requires me to accept a claim to knowledge only if I know it is justified and true (and believed). But that means that I have to know p as well as the person claiming knowledge. — Ludwig V

I don't think this is right. Someone can "justify" a claim to you and thereby show you that it is true. Thus one can learn from another on JTB precisely through the other's justification.

They’re not tools for mapping onto objects, but for enacting new forms of sense in our material and discursive interactions with the world. A hammer doesn’t “map” onto nails. Its usefulness lies in how we employ it to drive nails.Truth is a tool that in some contexts we use to check agreement with facts. In other contexts, we use it to contrast honesty vs lying; in others, to resolve disputes. In addition to the sense of truth as empirical/factual, one can think of grammatical/conceptual truth, performative/expressive truth, aesthetic/evaluative truth, narrative/interpretive truth and many other senses of meaning of that ‘same’ word.

Wittgenstein would emphasize that these aren't competing theories of truth but different tools serving different purposes in our linguistic practices. The mistake is assuming all these uses must share some common essence.​​​​​​​​​​​​​​​​ There’s no one metaphysical object “truth” that the word latches onto. — Joshs

Not that it matters, but this just seems intuitively right to me. What is it that prevents this view if truth being more widely accepted.

The best I can come up with is that claims to knowledge, like any other claim, have to be withdrawn if they turn out to be false. — Ludwig V

Well, yes.

Ok.

But Q1c was not about belief, but rather truth. Yes, it follows from believing something that I also believe it to be true, but that's not a reply to Q1c, which asks "Is it true?" Nothing I believe can supply the answer; it depends on the facts. — J

Well, yes, You seem to be expecting something from the JTB account that it does not provide. It's not a theory of truth.

It's not enough, for the sentence to be known, that we believe it to be true. It must also be true. — Banno

What bothers me is the interface between belief and reality. "It must be true" is the something more that is required. But once I have assessed the evidence, what more could there be? so I have difficulty in seeing what this amounts to. The best I can come up with is that claims to knowledge, like any other claim, have to be withdrawn if they turn out to be false. There may be cases in which the truth or otherwise of the proposition in question is finally and conclusively determined, but most of the everyday stuff doesn't come up to that standard. So the caution remains in place. — Ludwig V

But Q1c was not about belief, but rather truth. Yes, it follows from believing something that I also believe it to be true, but that's not a reply to Q1c, which asks "Is it true?" Nothing I believe can supply the answer; it depends on the facts.

JTB is supposed to help us evaluate knowledge claims -- keep us epistemologically honest. And on this construal, it can't.
— J
It doesn't tell us if they are true or not, so much as if they are known or not. — Banno


That's what I don't see how to separate. We both agree that only true things can be known. So if JTB tells us that X is known, it must also tell us at the same time that X is true. — J

I find that it helps out a lot to differentiate between the ontological and the epistemological in these matters:

Whether or not a belief is in fact true, and (given our ability to justify it) furthermore known, is a purely ontological issue. The occurrence of a truth—be "truth" defined as a correspondence to that which is actual, a conformity of belief or psyche to what is actual, or in some other such way—is either ontically actual or it is not.

Yet our only means of appraising what is ontological (or else ontically actual)—in this case, the reality of a truth—will be via some form of epistemology; and our utilized epistemology can, in at least theory, be either infallible or else fallible (with no other possibility being available to us).

If our epistemological appraisal of what is ontological happens to be infallible, there then is no possibility that we could be in any way wrong when we appraise a belief to be either true or not.

If—as any fallibilist will maintain—all possible epistemological appraisals can only be fallible, then our appraisal of a belief being either true or not will always be liable to some possibility of being wrong (with the likelihood of this possibility varying by degrees). And this is where (fallible) justification becomes paramount to our appraisal of what is (ontically) true: The quantity of justifications we can engage in can only always be temporally limited: There will always remain some yet awaiting potential “why” which goes unanswered in all that we justify—granting that we do not somehow obtain infallible justifications; our justifications are thereby always good enough for the purposes at hand, but can never be perfected in infallible manners.

Then, if we believe X, entailing that we thereby uphold our “belief that X” is in ontological fact true, and we can justify the X in question which we believe (at least with the epistemological honesty to recognize when our justifications no longer are sound, if they ever so become unsound), then we hold no grounds by which to presume that the truth of X is not in fact an ontologically occurrent given.

Again, in fallibilism, no justification (which is always epistemological in its nature) can guarantee the ontological occurrence of some given truth in question. One would need to have an infallible epistemology to do so. But, so long as one can soundly justify X at will as time permits irrespective of the data and possible counter-reasonings that might eventually surface, one then has no reason to suppose that one’s "belief that X" is not in fact ontologically true.

In short, when a truth occurs, it occurs ontically—and that which ontically is is not subject to the possibility of being wrong, i.e. fallibility. But we can only appraise what ontically is epistemologically, which will always be to some extent fallible.

As with the issue of truth, so too with the issue of knowledge as JTB. Knowledge can be ontologically had: if one’s belief is (ontically) true and one can justify it, one is then ontically in possession of knowledge (which can never be untrue and so can never be mistaken). But figuring out whether or not this is so will always be epistemological—and one’s applied epistemology, again, can either be infallible (in at least theory) or else can only always be fallible. So long as we can soundly, but yet fallibly, justify our “belief that X” to be ontologically true, we then have fallible justification for our “belief that X” to in fact be ontologically occurring knowledge.

To try to reduce possible confusion, how this works in practice: “I know that the planet is physical and roughly spherical,” is a claim of JTB. The justification—although always only good enough for the given purpose and always in some extreme philosophical sense yet fallible—for the belief that I hold being in fact ontologically true has so far always been sound. I thereby have no epistemological reason to presume that this belief which I can soundly justify at will is untrue (ontically). I thereby then have all the reason I need to conclude and uphold that my proposition is an (ontically) true belief I hold which I can (soundly) justify at will—and that it is thereby something I know as an ontological state of affairs, this in the JTB sense of “know”. Still, because this appraisal of what is ontically the case is wholly epistemological and not infallible, I can yet acknowledge that my appraisal of what I in fact know to be the case could in principle—at least hypothetically—be someday discovered to no longer be soundly justifiable, say due to new data. If this day ever arrives such that this proposition cannot at that point be honesty justified, then this belief will be evidenced to in fact be untrue (ontically): it will not in fact conform to that which is actual. And if in fact untrue, then I in fact do not (ontologically) know that which I so far deem to be knowledge.

You can replace the proposition given with any other, and the same will hold. For one example: “I know that 1+1=2”. If pressured, I might not be able to justify why this belief must conform to what is ontically actual in all possible cases (including all possible worlds), but if I can honestly justify it regardless without inconsistencies and if it does indeed happen to conform to that which is ontically actual in all possible cases, then this proposition will yet ontically be knowledge I hold. Same with “I know that I am not a brain in a vat”. Or else more trivial things, such as “I know that tomorrow it will rain”.

The reason I don't think it works is because if Smith were using "the man who will get the job" to refer to Jones, then there would not be an entailment involved. — Leontiskos

But Smith is using "the man who will get the job" to refer to Jones. Since Jones will not get the job, Smith's deduction is based on a false premiss and the conclusion is not justified (but not refuted either).

In that case rather than there being an entailment, Smith's two propositions would just be saying the same thing with different words. — Leontiskos

I don't follow this at all. Smith is not considering two propositions, but only one, and that proposition is false and so does not entail that the man who will get the job has ten coins in his pocket, so Smith's belief is justified only in a weak sense. It might be sufficient for the J clause in the JTB, but it is certainly not sufficient for the T clause.

Let me try again:-

But imagine, further, that unknown to Smith, he himself, not Jones, will get the job. And, also, unknown to Smith, he himself has ten coins in his pocket. Proposition (e) is then true, — Analysis. vol. 23 (1966)

It all depends on how you interpret the sentence "The man who will be appointed has ten coins in his pocket". As it stands here, the reference of "the man who will be appointed" is not fixed, or rather is fixed differently in the context of Smith's beliefs (where it refers to Jones) and in the context of the God's eye view of the narrator (and the audience) of Gettier's story (where it refers to Smith). In the context of Smith's beliefs (e) is justified but false, and in the context of the narrator and the audience, it is true. I don't know what criteria you have for "same proposition", but it seems to me that if a given sentence is true in one context and false in another, that sentence is expressing different propositions in each context. Certainly the same proposition cannot be true and false at the same time.

I don't think this is right. Someone can "justify" a claim to you and thereby show you that it is true. Thus one can learn from another on JTB precisely through the other's justification. — Leontiskos

Yes, perhaps I was a bit hasty there. Though if someone tells me that the earth goes round the sun, I can demand their proof and they can, no doubt, provide it - the data exist and the interpretation can be explained to me. But I would have to trust the data, or, perhaps collect a fresh set of data.

Again, in fallibilism, no justification (which is always epistemological in its nature) can guarantee the ontological occurrence of some given truth in question. — javra

That's a bit sweeping, isn't it? Certainly, an absolute guarantee of an empirical truth seems to be built in to their definition as contingent. But, if the conditions are met, surely we can guarantee the truth. Then there are the embedded or hinge propositions, which seem beyond the possibility of any coherent or rational doubt. Perhaps our choice is not between fallibilism or infallibilism across the board. After all, not all propositions (candidate truths) are of the same kind.

You seem to be expecting something from the JTB account that it does not provide. It's not a theory of truth. — Banno

That's true (sorry!), but it's a theory of knowledge that includes, as one of its criteria, that a statement be true. So if JTB tells us that X is known, it must also tell us at the same time that X is true.

But see my response to @javra, below.

This is a very helpful analysis. It sharpens the question, Are we meant to take the knowledge guaranteed by JTB as infallible or certain (@Janus's question)? You argue convincingly that we can't -- that this can't be the point of JTB. So if we're happy to substitute "has no reason to suppose that one’s 'belief that X' is not in fact ontologically true" as a synonym for "knowledge", then all is well. I don't know whether every proponent of JTB would be happy with this, though.

To try to reduce possible confusion, how this works in practice: “I know that the planet is physical and roughly spherical,” is a claim of JTB. — javra

Here, I wonder whether you misstated your target sentence. Are you talking about a JTB claim for "The planet is physical and roughly spherical" or for "I know that the planet is physical and roughly spherical"? A great deal depends on this, so I'll wait until you reply before going on.

Again, in fallibilism, no justification (which is always epistemological in its nature) can guarantee the ontological occurrence of some given truth in question. — javra

That's a bit sweeping, isn't it? Certainly, an absolute guarantee of an empirical truth seems to be built in to their definition as contingent. But, if the conditions are met, surely we can guarantee the truth. Then there are the embedded or hinge propositions, which seem beyond the possibility of any coherent or rational doubt. Perhaps our choice is not between fallibilism or infallibilism across the board. After all, not all propositions (candidate truths) are of the same kind. — Ludwig V

I did provide some justification for the claim in my previous post. That justification can either be infallible or fallible presents two alternatives that are mutually exclusive and collectively exhaustive. Or can anyone show this wrong by producing a third alternative alongside that of infallibility vs. fallibility?

Also, why would “seeming to be beyond the possibility of any coherent or rational doubt” completely/absolutely guarantee the truth of the matter such that there remains no possibility, irrelevant of how small, of being wrong?

As one banal example, why must something which by all accounts appears to all everywhere to be a vase on a table in fact necessarily be a vase on a table—such that it being a vase is true—rather than, say, being an extraterrestrial alien which is camouflaged as a vase, or else an advanced hologram (which maybe operates on all senses, such as that of touch, rather than only on sight), or some such alternative to the truth of it being a physical vase? Despite these possibilities, that it is a physical vase remains beyond the possibility of any coherent or rational doubt (given all the data and justifications available to us).

As I previously said, and as far as I know, all our justifications are always only good enough for the purposes at hand given the time limitations for the justifications we engage in—but they do not ever obtain a state of perfection wherein all possible questions or else issues have been consistently accounted for. And this thereby makes our justifications (here, implicitly understood, justifications for that which is true) less than infallible. They are thereby fallible in the strict technical sense of the word (i.e., liable to some measure of being wrong, irrespective of how small the possibility might be).

This is a very helpful analysis. It sharpens the question, — J

I’m very glad to hear it was helpful at least to some.

I don't know whether every proponent of JTB would be happy with this, though. — J

I know (in the JTB sense) that some out there are quite uncomfortable with the implications of fallibilism for issues of JTB.

To try to reduce possible confusion, how this works in practice: “I know that the planet is physical and roughly spherical,” is a claim of JTB. — javra

Here, I wonder whether you misstated your target sentence. Are you talking about a JTB claim for "The planet is physical and roughly spherical" or for "I know that the planet is physical and roughly spherical"? A great deal depends on this, so I'll wait until you reply before going on. — J

Trying to save some space, what I intended by what I wrote is that the proposition of “the planet is physical and roughly spherical” is taken to be an instance of knowledge, thereby being JTB claim (the first option you present). But, yes, it could have been better written.

I don't follow this at all. Smith is not considering two propositions, but only one, and that proposition is false and so does not entail that the man who will get the job has ten coins in his pocket,... — Ludwig V

If there were only one proposition, then how could there be an entailment? Gettier's argument depends on the entailment, and entailments involve at least two propositions. "The man who will get the job" does not refer to either Smith or Jones. It is a descriptor. What this means is that, contrary to your view, Smith is not uttering a tautology when he says, "Jones is the man who will get the job." Such an utterance is not the same as, "Jones is Jones," even for Smith.

Your theory amounts to the idea that when Smith says, "The man who will get the job has ten coins in his pocket," he is saying something false. But when someone else says the exact same sentence, such as the hiring agent who knows that Smith has ten coins in his pocket, he is saying something true. This goes back to what I said here:

Regarding the "false grounds," the key to the Gettier case is the difference between a material conclusion and a formal conclusion...

...Taken further we might say that a valid conclusion is different from a sound conclusion, and therefore John and Ben have reached different conclusions. — Leontiskos

So I think a material conclusion can differ from a formal conclusion, for example when both say the same thing and yet the "therefore" of the first is merely valid whereas the "therefore" of the second is sound. This may even go further and apply to propositions themselves rather than mere conclusions, as I surmised in that post. But I don't see that what is at stake is a simple matter of reference, as if there is only one proposition and no entailment occurring.

Yes, perhaps I was a bit hasty there. Though if someone tells me that the earth goes round the sun, I can demand their proof and they can, no doubt, provide it - the data exist and the interpretation can be explained to me. But I would have to trust the data, or, perhaps collect a fresh set of data. — Ludwig V

Yes, and I would go farther and say that you can see that their argument is correct. It's not so much a matter of trusting them.

That's true (sorry!) — J

There is an interesting meta-question here. Given that you don't actually believe in truth or knowledge and therefore are forced into an intersubjective notion of truth, here in this thread we have an example where you are at an intersubjective loss. What you are saying in this thread is simply false on an intersubjective approach to truth, given that literally everyone is disagreeing with you. Does that mean that you should accept that what you are saying is false and give up this strange line of argument (given that you yourself think truth is an intersubjective phenomenon)? Or is there something more to truth than intersubjectivity? Are you allowed to hold that although your claims about JTB are intersubjectively false, they are nevertheless not false?

If—as any fallibilist will maintain—all possible epistemological appraisals can only be fallible, then our appraisal of a belief being either true or not will always be liable to some possibility of being wrong (with the likelihood of this possibility varying by degrees). — javra

Right, and I think this is the more central piece for @J, along with what has said. It goes back to this:

The counterargument could be phrased this way:

1. Truth is always known via justification, and ensured by justification
2. Justification can never overcome the possibility of the one-in-a-million anomaly
3. Therefore, truth is never certain

This form of skepticism is a bit like the claim that epistemology is like a game of pool and no matter how good you are, there is always a chance that your shot will not pocket the 9-ball. Accidental contingencies are always involved, and therefore the best one can hope for is a good probability (or an ↪inference to the best explanation). Such a skeptic would say, "The only way to guarantee that the 9-ball is pocketed would be to pick it up with your own hand and place it into the pocket directly, but that would be cheating." — Leontiskos

Put more simply, for someone like @J every knowledge-claim involves guessing, and therefore there is no knowledge that is qualitatively different from a guess. Everything he is arguing about JTB is dependent on this form of skepticism that is so foundational for him. Truth is going to be a problem for him in any circumstance, JTB or otherwise. He will make (and has made!) the same objections to anyone who talks about truth as if it is a meaningful category, whether they hold to JTB or not.

You make repeated mention of skepticism. Of a Cartesian or of a Ciceronian variety? (the latter being a good example of an Ancient Skeptic—in both his theories and his lifelong praxis) The two versions staunchly contradict. But maybe that’s a separate issue.

As to this,

1. Truth is always known via justification, and ensured by justification
2. Justification can never overcome the possibility of the one-in-a-million anomaly
3. Therefore, truth is never certain — Leontiskos

Item #1 I find blatantly wrong in so far as, for example, I know the truth of the color of an object as it appears to me not by justification but by brute awareness/experience. But yes, successful justification wherever needed validates that what we take to be (ontically) true in fact so is.

Item #2 might be a less cordial way of saying that all justification is to some extent fallible. As per my posts here and here, I do uphold this.

Lastly, item #3 clashes with what I’ve stated in my posts. When differentiating the ontological from the epistemological, ontically occurring truths (which are absolutely certain and not possible to be wrong) do occur all the time. But our epistemic appraisals of what are and are not ontic truths (the latter, again, do occur) will be fallible to some measure.

Therefore, ontic truths are always (completely) certain, and are that toward which we (at least some) ideally aspire. This by optimally (which is different from “perfectly”) justifying our beliefs (by my count, with each belief being in essence a psyche’s ascent (conscious or otherwise) to that which is in fact actual—such that to believe that X is to believe that X is true, i.e. corresponds/conforms to what ontically is).

Hence, in one possible summation of what I previously expressed: Ontic truths are, and are always certain. Our epistemic appraisal of what are and are not ontic truths, however, will always be to some extent liable to being wrong. Call the latter "epistemic truths". And it is for this reason we then honestly seek to justify our epistemic turths whenever required: if our justifications remain consistent given all available data and reasoning, there then is no reason to conclude or even assume that our beliefs of what is ontically true are in fact mistaken, thereby allowing us to maintain that our beliefs are ontically true (only when our justifications become inconsistent with data or coherent reasoning, and are thereby endowed with contradictions, can the honest person conclude that their belief of what is ontically true is in fact mistaken and, hence, ontically untrue).

Ontic truth is always certain, in the sense of "completely assured, fixed, and unvarying". Epistemic truth, while aspiring to be one and the same with ontic truth, is however not "completely assured, fixed, and unvarying", for it might in time change with new data or reasoning.

it could have been better written. — javra

No worries, I'm not always a model of precision myself.

the proposition of “the planet is physical and roughly spherical” is taken to be an instance of knowledge, thereby being [a] JTB claim — javra

OK, good, so on this construal, JTB becomes a reasonable description of our ontic and epistemological requirements. We're not saying that "The planet is physical and roughly spherical" is known to be true, pre-JTB. Nothing is known to be true, in that non-fallibilist sense.* Rather, we bring our belief and our (presumably pretty impressive) justifications, and fill in the "T" with some such formula as you used above. The result is knowledge. This should make us suitably modest about what knowledge actually consists of, but at the same time extremely confident that the target statement is knowledge if anything is.

* The monkey wrench is logical and other putatively analytical truths. I think such statements require a different series, and type, of arguments to explain what knowledge of them would mean. Historically, was JTB proposed as being useful for determining that kind of knowledge? I'm used to thinking of it as an attempt to evaluate knowledge claims about the world, but I don't know the back-story. There's something odd about asking whether "If A, then not (~A)" is a belief, or how we might justify it. But I'll leave that for others.