So against what measure am I comparing my belief that the square root of four is one, in order that it is wrong? — Isaac

There is no measure. It’s just either right or wrong.

Do you understand the difference between mathematical realism and mathematical formalism? The solipsist says that we cannot know that mind-independent mathematical entities (as per realism) exist. He doesn’t say that we cannot get string manipulations wrong (as per formalism).

To me the tricky part is that the solipsist is making claims about any rational agent, existence or not. — Pie

Yes. It’s no different to saying “no human has two heads” which is true if I’m the only human or if I’m one of seven billion.

It’s no different to saying “no human has two heads” which is true if I’m the only human or if I’m one of seven billion. — Michael

I disagree. The form is similar, but I claim that concepts are special. Consider the claim: It’s no different to saying “no human has two heads. It's a claim about norms that bind us both, that either transcends you or has no force.

I disagree. The form is similar, but I claim that concepts are special. — Pie

How about “no human can know the future”. That’s true whether I am the only human or one of seven billion. The same with “no human can know that another thinking thing exists”. And the same with “no human can know that mind-independent objects exist”.

There is no measure. It’s just either right or wrong. — Michael

OK, so how do we know if not by comparing the wrong belief to the right one and finding it not to match?

Do you understand the difference between mathematical realism and mathematical formalism? — Michael

I believe so, yes, though I'm far from expert on the matter. But I don't see how formalism rescues the solipsist.

I can manipulate the symbols assuming the square root of four is one. I can find some outcome from going so. How does that outcome show I'm wrong? Maybe it's the outcome I'm supposed to get from that operation.

OK, so how do we know if not by comparing the wrong belief to the right one and finding it not to match? — Isaac

How do you know which belief is right so which to use as a comparison? At the moment you seem to be arguing that any knowledge (of maths) is impossible?

I believe so, yes, though I'm far from expert on the matter. But I don't see how formalism rescues the solipsist. — Isaac

The point is that being wrong doesn’t depend on the existence of mind-independent entities. We can get maths wrong even if mathematical realism is false. So the claim that the solipsist’s position that we can’t know that mind-independent objects (or other minds) exist somehow entails that no claim is truth-apt is evidently wrong.

How do you know which belief is right so which to use as a comparison? — Michael

The one used by mathematicians is right. We just ask.

Not a course open to the solipsist.

being wrong doesn’t depend on the existence of mind-independent entities. We can get maths wrong even if mathematical realism is false. — Michael

I'm enquiring as to how. If not by some sort of comparison to the right answer, then by what means?

Am I to think that you imagine the possibility of a Kant without some rich culture that birth and trained him, gave him the very languages of his art ? — Pie

What....you never heard the expression “thinking outside the box”? What is a culture if not a box? Being in a culture and conditioned by it, does not necessitate being restricted to it.

My focus on language is simply that of an epistemologist trying to figure out a philosopher's minimum commitment. — Pie

......but there’s nothing in that that says the philosopher’s minimum commitment has to be language, which implies you’re focus is misplaced, or, being an epistemologist is not the proper discipline for figuring a philosopher’s minimum commitment. I would say a philosopher’s minimum commitment, is understanding. What can any philosopher accomplish if he understands nothing? Which means he must understand something, which means he must possess a fully functional faculty for understanding. As it so happens, a transcendental metaphysician is more adept at figuring a philosopher’s minimum commitment than an epistemologist, who actually is only interested in the philosopher’s minimum knowledge, which he could never determine anyway.

I oppose the view that (most) concepts are 'pre-given' — Pie

Pre-given carries a temporal implication. Pre-....what? Most are not pre-anything, arising spontaneously with initial perception of a given real object, but some are pre-cognition, according to one specific view. Pretty obvious, I should think. Conceptions refer to something represented by its object, but there are concepts that refer to something that does not have an object that represents it. Cause is a concept, but there is no representable cause object, but only objects represented as being caused or causal. Beauty is a concept, but there is no beauty object, only objects that are beautiful.
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Was it not clear that my point was about language acquisition ? — Pie

Nope....I musta missed it. My impression has been that you’ve merely presupposed it, at least for all intents and purposes. What was your point about language acquisition?
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Then koncepts are public and what actually matters here. — Pie

.....which implies the concepts used in private thought don’t actually matter here. That’s fine, concepts are nothing but notions in a speculative theory with respect to human cognition. Something makes private thought possible, or, there is no such thing as private thought. Pick your own preferred bondage, right? Would you saw off the limb you’re sitting on, by allowing that humans think, but find no authorization for allowing it?
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I suggest that it's not confusion but simply a matter of replacing a broken theory with something better. — Pie

“Something better” and “broken theory” are subjective judgements. Who says it’s better, and, better than what? And what’s broken about some extant theory? The insight “meaning is use” just changes the location of “use”, from the internal, rational with respect to a system, to the external, empirical with respect to a language. Left out of the insight, and solving the riddle of possible human cognitive extravagances, is.....time. Doesn’t matter that meaning is use, insofar as no use of any linguistic representation is prior to the concept to which it belongs.

Instead of what's essentially a theology of mystic Forms..... — Pie

So....you know what justice is because you’ve experience things that seem just or unjust to you? How does an experience of an unjust incident inform you of how it could be so, if you didn’t already have an idea what form justice itself must have?

(Well, shucks, Mr. Bill. If you’ve seen enough injustice, you know what justice is, because it isn’t that.)

It isn’t that ad infinitum still doesn’t tell you what it is, and if you are not informed as to what it is, you cannot explain why it seems otherwise. So the lackadaisically disinterested end up with, “well, damned if I know. It just is”, then go about their day kicking the cat or running over the trash barrel some fool left in the driveway.

The one used by mathematicians is right. We just ask. — Isaac

There are plenty of unsolved problems in maths, e.g the Reimann hypothesIs. Are you saying that the Reimann hypothesis isn’t truth-apt because it hasn’t been solved? Or does its truth (or falsity) depend on mathematical realism? Or perhaps it’s true (or false) despite mathematicians not having solved it and despite mathematical realism not being the case?

I'm enquiring as to how. If not by some sort of comparison to the right answer, then by what means? — Isaac

How what? How we can know that we’re wrong? Maybe we can’t (a point in favour of skeptical positions like solipsism). But we don’t need to know that we’re wrong to be wrong.

How about “no human can know the future”. — Michael

Is that an empirical claim ? Or a metaphysical claim ? If it's a metaphysical claim, it's a claim about the concepts knowledge and future, it seems to me.

Is that an empirical claim ? Or a metaphysical claim ? If it's a metaphysical claim, it's a claim about the concepts knowledge and future, it seems to me. — Pie

I don’t know. Does it matter? I don’t need mind independent objects to exist to have the concept of numbers. I can be the last man alive and yet have the concept of whatever newly mutated monstrous plant emerges from the wasteland. This notion of yours that concepts depend on there being multiple thinking things or mind-independent objects is very wrong.

In fact, your very argument is that private thoughts and sensations have nothing to do with meaning or concepts or whatever, so that there is meaning and concepts and whatever isn’t evidence that there are other things with private thoughts and sensations.

Although I still don't know how you account for the fact that there is the concept of private thoughts and sensations.

What....you never heard the expression “thinking outside the box”? What is a culture if not a box? Being in a culture and conditioned by it, does not necessitate being restricted to it. — Mww

Of course. Clearly the box is extended by intellectual pioneers...and more literal pioneers who bring back moon rocks or deepsea lifeforms. Clearly concepts are extended, introduced. No one disputes the role of individuals in our 'open source' communal operating system (the language itself and the concepts we've adopted and mastered together.)

....but there’s nothing in that that says the philosopher’s minimum commitment has to be language.. I would say a philosopher’s minimum commitment, is understanding. — Mww

Your version of understanding, if we grant a nonlinguistic version of this in the first place, isn't enough. What sense can 'philosophy' have if no conversation is possible ? If no beliefs can be settled publicly and reasonably ? Understanding without language is pointless, unless you really are happy with some kind of paradoxically solipsistic or mute theory of rationality and science. Here we are, sir, trying to settle the way we ought to conceive the minimal epistemic situation, mostly in English, our jointly inherited and even largely-self-constituting software.

“Something better” and “broken theory” are subjective judgements. Who says it’s better, and, better than what? — Mww

We settle it, the rational community as a whole. We make and defend claims, presenting candidate beliefs for the tribe. Our second-order tradition takes no claim or claimant to be sacred As Kant saw, reason is autonomous, one and universal, and we 'rational ones' (who acknowledge only reason(s) as an authority) hash it out, as you and I are doing here, playing our relatively tiny roles.
I claim that what Ryle calls the 'official story' is indeed broken, essentially passing on the (old) news that a strong case has been made a certain metaphysical tradition. 1781 was a very good year, but it was not the end of philosophical history.

And what’s broken about some extant theory? — Mww

I've mentioned quite a few issues already. I understand that folks think Wittgenstein is trying to steal their soul, so I'd recommend Ryle. I recall that you hate linguistic philosophy, but language is what you must make your case in. If you hide from this simple fact...the humans make a case for their beliefs in a shared language...then you seat yourself at the children's table. It's fine to postulate something like Platonic-forms, God-given Concepts, whatever...but a case must be made in the language we share, in the 'koncepts' we share. The rest is escapism, mysticism, diarykeeping....

So....you know what justice is because you’ve experience things that seem just or unjust to you? How does an experience of an unjust incident inform you of how it could be so, if you didn’t already have an idea what form justice itself must have? — Mww

Are you so sure that AI couldn't be train to predict with high accuracy whether the description of an action as unjust ? Does it have an idea ? Especially as translation software gets better, we should pull back on our theological certainties about our divine source. Or can kangaroos have their own kangaroo Kant, spelling out their eternal structure of kangaroo experience ?

We could actually talk about semantics if you want. The best story I've heard lately is inferentialism, which I'd call a structuralist approach to meaning. For instance,

Observational vocabulary is not a vocabulary one could use though one used no other. Non-inferential reports of the results of observation do not form an autonomous stratum of language. In particular, when we look at what one must do to count as making a non-inferential report, we see that that is not a practice one could engage in except in the context of inferential practices of using those observations as premises from which to draw inferential conclusions, as reasons for making judgments and undertaking commitments that are not themselves observations.The contribution to this argument of Sellars’s inferential functionalism about semantics lies in underwriting the claim that for any judgment, claim, or belief to be contentful in the way required for it to be cognitively, conceptually, or epistemically significant, for it to be a potential bit of knowledge or evidence, to be a sapient state or status, it must be able to play a distinctive role in reasoning: it must be able to serve as a reason for further judgments, claims, or beliefs, hence as a premise from which they can be inferred.

https://sites.pitt.edu/~rbrandom/Texts/Pragmatism_Inferentialism_and_Modality_i.pdf

There are plenty of unsolved problems in maths, e.g the Reimann hypothesIs. Are you saying that the Reimann hypothesis isn’t truth-apt because it hasn’t been solved? Or does its truth (or falsity) depend on mathematical realism? Or perhaps it’s true (or false) despite mathematicians not having solved it and despite mathematical realism not being the case? — Michael

It's true if enough mathematicians agree that's the way things will be. Otherwise they might say (of the proof) "Ah if 1+1=2, the the Reimann hypothesis is true...we'd rather 1+1 no longer =2 and the Reimann hypothesis be false" If they all (or mostly) agreed, then that's what maths would be. A person on their own could not possibly be wrong because they could just decide which it was to be (having discovered the proof for the Reimann hypothesis) and make either the hypothesis true, or the axioms on which the proof is based false. How would they decide which?

How we can know that we’re wrong? Maybe we can’t (a point in favour of skeptical positions like solipsism). But we don’t need to know that we’re wrong to be wrong. — Michael

No, but you need to show that it's possible, to support a hypothesis that a solipsist can be wrong. You can't just declare they can and then when asked how say "don't know". If there's no plausible means by which they can be wrong, the rational conclusion is that they can't be wrong.

If there's no plausible means by which they can be wrong, the rational conclusion is that they can't be wrong. — Isaac

You're not asking for a plausible means by which they can be wrong. You're asking for a plausible means by which they can know that they're wrong. That's not the same thing.

The means by which they can be wrong is just being wrong. If they believe that the Reimann hypothesis is correct, but it isn't, then they're wrong. If they believe that the Reimann hypothesis is not correct, but it is, then they're wrong.

The means by which they can be wrong is just being wrong. If they believe that the Reimann hypothesis is correct, but it isn't, then they're wrong. If they believe that the Reimann hypothesis is incorrect, but it is, then they're wrong. — Michael

But you've not given an account of what it would mean to be wrong for a solipsist. It's not about them knowing.

I gave the example of comparing one's own belief to the state of the world as measure of being wrong (or one's own answer in maths to the right answer of the mathematicians). One needn't carry out the comparison. One could remain entirely in the dark about it. The fact remains that I've given an account of what it would mean to be wrong (that your answer doesn't match the right answer). What is the equivalent account for solipsism?

But you've not given an account of what it would mean to be wrong for a solipsist. — Isaac

Believing that the Reimann hypothesis is correct, but it isn't. Or believing that God exists, but he doesn't. Or believing that there are other people with private thoughts or sensations, but there aren't. Or believing that the world will end in 10,000 years, but it won't.

It's not about them knowing. — Isaac

I gave the example of comparing one's own belief to the state of the world as measure of being wrong — Isaac

If it's not about knowing then why are you asking about measures?

Believing that the Reimann hypothesis is correct, but it isn't. Or believing that God exists, but he doesn't. Or believing that there are other people with private thoughts or sensations, but there aren't. Or believing that the world will end in 10,000 years, but it won't. — Michael

I'm asking about the "...it isn't", "...he doesn't", "...it won't" parts. What do any of those propositions mean for a solipsist? How are they any different to the belief in the first place?

If it's not about knowing then why are you asking about measures? — Michael

Because a difference in measure is a plausible account of what it means to be wrong. No one need check, or know that such a difference is the case. It's just that if there were such a difference, you'd be wrong. I'm asking for such an account for the solipsist.

I recall that you hate linguistic philosophy, but language is what you must make your case in. — Pie

I have no use for OLP, but I have no choice but to use language, iff I wish to make a case. As I said....or maybe I deleted because I decided not to make that case.....expression which requires only a singular subjectivity, or communication, which requires a plurality of subjectivities, are only possible through a medium that is not subjective.
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Your version of understanding, if we grant a nonlinguistic version of this in the first place, isn't enough. — Pie

It is enough for what it does; it is not enough for that which is beyond its power. My version of understanding represents the biggest wheel in the set of cognitive gears, nothing more, nothing less. It can do nothing by itself, but nothing can be done without it. That’s how systems work. Theoretically.
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As Kant saw, reason is autonomous, one and universal, — Pie

Yeah, well....in Kant, autonomy does not relate to universality, but causality, so whoever said Kant said, or meant, that, has merely suited himself to his own ends. And as you say, we are entitled to interpret, but we do not have license from that entitlement, to subvert.
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How does an experience of an unjust incident inform you of how it could be so, if you didn’t already have an idea what form justice itself must have?
— Mww

We could actually talk about semantics if you want. — Pie

No need. I just presented an opportunity for you to ask yourself a question. Shouldn’t be any more difficult, or use any other faculties, than asking yourself what would be nice to have for dinner.

I'm asking about the "...it isn't", "...he doesn't", "...it won't" parts. What do any of those propositions mean for a solipsist? How are they any different to the belief in the first place? — Isaac

Because a difference in measure is a plausible account of what it means to be wrong. No one need check, or know that such a difference is the case. It's just that if there were such a difference, you'd be wrong. I'm asking for such an account for the solipsist. — Isaac

I just don't understand your question at all. Consider the simple disquotational account of truth:

"God exists" is true iff God exists.

If the solipsist claims that God exists then he is wrong if God doesn't exist.

I don't understand why you think the solipsist's claim that knowledge of other minds and mind-independent objects is impossible entails that he can't be wrong (or right) about God's existence. There is literally no connection between these positions. So please, help me understand your reasoning, because there is none as far as I can see.

Consider the simple disquotational account of truth:

"God exists" is true iff God exists. — Michael

There are two sides to that expression. One is currently a proposition, but we're assuming that it is a proposition representing the belief of the solipsist. The other is what? Another belief of the solipsist?

Even if we abandon the assumption, we could say one is a proposition, the other is about what is the case. But even in this restricted definition, all you've demonstrated is that the solipsist could lie (say "God exists" when in fact God doesn't exist). That's not the same as being wrong.

But even in this restricted definition, all you've demonstrated is that the solipsist could lie (say "God exists" when in fact God doesn't exist) — Isaac

A falsehood isn't a lie.

A falsehood isn't a lie. — Michael

Exactly. But if the solipsist says "God exists" when God doesn't exist, then they are just lying, not telling a falsehood because God (and his existence) is entirely in their mind, and so saying "god exists" is giving a false report of the contents of their mind - lying.

But if the solipsist says "God exists" when God doesn't exist, then they are just lying — Isaac

No, they could honestly believe that God exists. They're just wrong if he doesn't.

No, they could honestly believe that God exists. They're just wrong if he doesn't. — Michael

How? If God is in their mind, how can they possibly believe one thing about him, when in fact another is the case. What would it mean for something in your mind to be the case, but for you not to believe it is (or vice versa)?

You'd have to separate the mind into two halves - that which holds what is the case, and that which holds beliefs about the other half (which can then be wrong).

But if that's the case then you've still got one half inferring hidden states. The very state of affairs the solipsist is using to deny the external world. So they'd have to deny the 'hidden half' too. Thus leaving them with no theory.

If God is in their mind — Isaac

Why would God be in their mind?

Why would God be in their mind? — Michael

Because all that exists is their mind, and so God must be in it.

Because all that exists is their mind, and so God must be in it. — Isaac

The epistemological solipsist claims that we can't know that other minds and mind-independent objects exist. He doesn't claim that other minds and mind-independent objects don't exist. That would be ontological solipsism.

The epistemological solipsist claims that we can't know that other minds and mind-independent objects exist. He doesn't claim that other minds and mind-independent objects don't exist. That would be ontological solipsism. — Michael

Yes, I understand that (primarily because you explained it earlier). But to claim we can't know that other minds and mind-independent objects exist, it must be plausible that they don't. Otherwise we can know. If it is implausible that X doesn't exist, this is one way we can know that X exists.

So if it is implausible that God is in your mind (because that would mean you couldn't be wrong...etc), then we can know that god cannot be just in your mind. We can rule out that option and so 'know' that what is the case must be one of the remaining options.