As far as my perception informs me, it was unchanged, which is merely to highlight that to say change is always of things is not to say there is always change in the thing. — Mww

There probably is always change in the thing even though we cannot perceive it. Again, though that is a matter of perspective —the 'for us' vs the 'in itself'.

One Copernican Revolution to rule them all. — Mww

It's odd to call Kant's critique a "Copernican Revolution" though because he put humanity right back at the centre of things.

Yes — Michael

If so, then we can move on. In the SEP article the independent proof mentioned above is presented as having two types of assumptions, epistemic and modal.
The epistemic assumptions are:
$K(p \wedge q) \vdash Kp \wedge Kq$
$Kp \vdash p$
Now in the main these are not seen as problematic, with the few exceptions noted at 3.1.

The modal assumptions are
$If \vdash p, \text{then } \vdash \Box p.$
$\Box \neg p \vdash \neg \Diamond p.$


The intuitionist response excludes double negation and quantified exchange. I have some sympathy for this being a suitable approach to an antirealist mathematics, along constructionist lines. Accepting that no truths are unknown in mathematics might be understood as simply not having assigned a truth value to formulae outside of our deductions, perhaps along the lines of Kripke's theory of truth. Hence no truths are unknown and yet not all truths are known. I think this mostly gets around the objections of 3.3 and 3.4 in the SEP article, but do not consider the issues closed.

But this will not work with medium size small goods - with cats in boxes. If the cat is in the next room, with the box, but unobserved, there is a place for saying that it is either in the box or it is not, and not simply that we have yet to assign a truth value to "the cat is in the box".

Here again is my suggestion that the choice between realism and antirealism is dependent on context.

Thoughts?

It's odd to call Kant's critique a "Copernican Revolution" though because he put humanity right back at the centre of things. — Janus

I think the point was relocation of center. One de-centered Earth in favor of the Sun, the other de-centered various forms of ens realissimum in favor of a certain form of thinking subject.

As for the plate and congruent macro-conditions, as long as my food stays where my fork can get to it, I’m good, as I’m relatively sure the plate-in-itself will be just as good…..whatever it may be.

Perspective, yes indeed.

Yes, that works for me.

Doncha just love it when a plan comes together?

Yes, it is most satisfying!

I already explained it. We can say something is true now about what would be in the future. Can we say it would be true in the future absent us? So if truth or falsity is a property of propositions and it is true that the gold will exist in the non-human future do you say it will also be true in that non-human future that there is gold when there are no propositions? — Janus

Do you want to say that, "X will be true tomorrow," is different from, "Tomorrow, X will be true"? I don't see a proper distinction between the two.

In other words I'm suggesting that truth is propositional and existence is not. — Janus

But is there an existence-claim that is not simultaneously a truth-claim? Can we talk about what exists apart from what is true?

Would God be capable of knowing what is true and what is false? — Janus

Sure, God knows the true from the false. A theist could uncontroversially say that even if all humans died, truth would remain.

Do you want to say that, "X will be true tomorrow," is different from, "Tomorrow, X will be true"? I don't see a proper distinction between the two. — Leontiskos

I'm not saying X will be true tomorrow, but that it is true now that X will be tomorrow. If truth is a property of propositions, then it follows that 'no propositions, no truth'. If existence is not a property of propositions, then it does not follow that ' no propositions no existence'. truth

But is there an existence-claim that is not simultaneously a truth-claim? Can we talk about what exists apart from what is true? — Leontiskos

No we cannot make claims about what exists or will exist without (implicitly at least) proposing that what we say is true. But what will exist or not exist does not depend on what we say.

Sure, God knows the true from the false. A theist could uncontroversially say that even if all humans died, truth would remain. — Leontiskos

That seems right, although I would have used 'consistently' instead of 'uncontroversially'. By the same token an atheist who believes that truth or falsity is a property of propositions, but that existence is not, can consistently say that something will exist, even in the absence of humans. but cannot consistently say that truth can be in the absence of propositions.

By the same token an atheist who believes that truth or falsity is a property of propositions, but that existence is not, can consistently say that something will exist, even in the absence of humans. but cannot consistently say that truth can be in the absence of propositions. — Janus

Except "that something will exist" is a propositional truth. So he hasn't managed to speak about existence apart from propositions and truth.

I have to run, but I will address the rest your post in the future.

Except "that something will exist" is a propositional truth. So he hasn't managed to speak about existence apart from propositions and truth. — Leontiskos

I've already addressed this objection:

No we cannot make claims about what exists or will exist without (implicitly at least) proposing that what we say is true. But what will exist or not exist does not depend on what we say. — Janus

@Michael

The paraconsistent revision (SEP 3.5) is interesting, and again I would not dismiss it offhandedly. It's a reminder that knowledge remains more a family resemblance than a strict category. A "paraconsistent constructive relevant modal logic with strong negation" would be a strange beast indeed. Wansing's article is here, but I've only had a quick look. They present an axiomatisation and proof of completeness.

Now these are the reinterpretations of Fitch that are addressed in the article. I had thought you were offering a different reinterpretation, but in classical logic, and hence was puzzled as to how that might work. But it seems you are offering a semantic restriction? You seem to want to do more than to reject those things that it is logically impossible to know...?

And are either TKP or DKP intuitive to you? Neither are to me. If the debate between Williamson and Tennant is ongoing, then this approach is not all that useful at present.

But KK (SEP 5.3) is for me intuitive. So that it is irreconcilable with SKP is telling.

It does seem to me that antirealism can be consistent by committing to an intuitionistic logic. But otherwise, perhaps not.

Are you happy with that, as is Dummett? This calls back to a discussion from years ago, on Devitt: . I still favour Devitt.

So to the first section, in which Devitt characterises realism as the view that physical entities exist independently of the mental. Devitt notes with considerable glee that there is nothing in this definition about truth. He goes on to point out that truth is independent of the evidence at hand. "Truth is one thing, our means of discovering it, another". Hence, according to Devitt, "no doctrine of truth is constitutive of realism". — Banno

Your argument is presumably something like this, "If three humans exist and there are no other minds, and one person dies, then it is still true that there is gold in Boorara. The second dies, and it is still true. By induction we should hold that if the third dies, it will still be true. If the truth was not affected by the death of the first two people, then surely it will not be affected by the death of the third." — Leontiskos

Looks to be another example of your altering an argument to an unrecognisable degree.

No, the argument is not an induction. It is a deduction. There is gold in Boorara. If nothing changes, then there will be gold in Boorara. If life disappears, and nothing else changes, there will still be gold in Boorara.

Its not hard. If something does not change, then it stays the same. If there is gold, and that does not change, then there is gold.

Now you want to do something a bit more, along the lines that if there are no minds, then there can be no propositions, and hence no true proposition. Quite right. But that again does not change the gold at Boorara. Proposition or not, if nothing else changes, it will still be there.

You seem to want to do more than to reject those things that it is logically impossible to know...? — Banno

I'm suggesting just the bare minimum to avoid Fitch's paradox:

∀p∀q((p ⊭ (q ∧ ¬Kq)) → (p → ◊Kp))

The only unknowable truths are "p is an unknown truth".

And are either TKP or DKP intuitive to you? — Banno

I think my version is TKP. His phrasing is just a little more general, claiming that if it is a contradiction to know some p then we cannot know p. I'm just not sure what other than "p is an unknown truth" this would include.

So to the first section, in which Devitt characterises realism as the view that physical entities exist independently of the mental. Devitt notes with considerable glee that there is nothing in this definition about truth. He goes on to point out that truth is independent of the evidence at hand. "Truth is one thing, our means of discovering it, another". Hence, according to Devitt, "no doctrine of truth is constitutive of realism". — Banno

Antirealism isn't simply phenomenalism or idealism; it can be consistent with physicalism (and property dualism).

I think the IEP article on brains in a vat provides a better account:

One proposal is to construe metaphysical realism as the position that there are no a priori epistemically derived constraints on reality (Gaifman, 1993).

...

One virtue of this construal is that it defines metaphysical realism at a sufficient level of generality to apply to all philosophers who currently espouse metaphysical realism.

...

For there is a good argument to the effect that if metaphysical realism is true, then global skepticism is also true, that is, it is possible that all of our referential beliefs about the world are false. As Thomas Nagel puts it, “realism makes skepticism intelligible,” (1986, 73) because once we open the gap between truth and epistemology, we must countenance the possibility that all of our beliefs, no matter how well justified, nevertheless fail to accurately depict the world as it really is. Donald Davidson also emphasizes this aspect of metaphysical realism: “metaphysical realism is skepticism in one of its traditional garbs. It asks: why couldn’t all my beliefs hang together and yet be comprehensively false about the actual world?” (1986, 309)

But then maybe we need to distinguish between two types of realism; one that denies phenomenalism/idealism and one that denies the (restricted) knowability principle. Labels notwithstanding, Devitt's "realism" might be consistent with Dummett's "anti-realism".

But this will not work with medium size small goods - with cats in boxes. If the cat is in the next room, with the box, but unobserved, there is a place for saying that it is either in the box or it is not — Banno

And the antirealist will agree, because the antirealist denies the conclusion of Fitch's argument (either because they are intuitionists or because they only argue for a restricted knowability principle). The antirealist only claims that if the cat is in the box then it is possible to know that the cat is in the box, whereas the realist allows for the impossibility of knowing, e.g. they will claim that in at least one case the cat is in the box but either it is impossible in principle to look in the box and see the cat or looking in the box and seeing the cat does not justify the belief that the cat is in the box. This kind of scenario, according to someone like Dummett, is incoherent.

∀p∀q((p ⊭ (q ∧ ¬Kq)) → (p → ◊Kp)) — Michael

Isn't this just saying that what we know must be consistent? That's compatible with realism. It also looks compatible with the SKP: p↔︎◇Kp; and KK: ☐(Kp→KKp). So I don't see it avoiding Brogaard and Salerno's response.

Antirealism isn't simply phenomenalism or idealism — Michael

Sure. Not sure why you feel the need to point this out. I agree, at least tentatively, with Devitt that Realism is not an explicit doctrine of truth. But antirealism in contrast does seem to commit to one or other non-binary theory of truth.

I don't see that it counts against realism that it might permit global skepticism. We have other reasons to reject global skepticism.

I've already addressed this objection — Janus

You haven't shown your defense to be coherent:

I'm not saying X will be true tomorrow, but that it is true now that X will be tomorrow. — Janus

"X will be tomorrow"? What does that mean, other than, "X will be true tomorrow?" As I said above, there are no existence predications which are not truth predications.

When my sister tells my nephew to eat his broccoli, he will push it around the plate. You are pushing the contradiction around in your system, without ultimately addressing it. You want to say that a claim about the future involves no claim about what will be true in the future, and that's not coherent.

As I said above, there are no existence predications which are not truth predications. — Leontiskos

What could this be saying? What is an "existence predication"? Quantification? Or just predication? Are you just saying that any predication has a truth value? Or anything more than that "f(x)" is true IFF f(x)?

Now you want to do something a bit more, along the lines that if there are no minds, then there can be no propositions, and hence no true proposition. Quite right. But that again does not change the gold at Boorara. — Banno

How could it not? You want to say that if all minds ceased to exist, it both would and would not be true that there is gold in Boora. On the one hand you say that the truth (or the gold) must "stay the same." On the other hand, you say that there are no true propositions apart from minds.

"It would still be there," is a proposition which you hold to be true. At no point does, "It would still be there," become a non-proposition.

But what is at stake here is not reified and accidental propositions as you conceive them. We are asking about the relation between truths and minds. Either you think that there can be truths without minds or you don't. Either you think that there can be truths-about-what-exists without minds or you don't.

Just so you know, I am not planning to pursue this topic very far with you. I have reason to believe it is not something you want to discuss in depth.

You want to say that if all minds ceased to exist, it both would and would not be true that there is gold in Boora — Leontiskos

No, I don't. You are confusing the sentence with its extension. There would be gold in Boorara, even if there were no folk around to know that there was gold in Boorara. Repeatedly, you pretend that others are the presenting arguments you want them to present, not the argument they are presenting. I guess that makes things much easier for you.

Just so you know, I am not planning to pursue this topic very far with you. — Leontiskos

That's not surprising. Your supposed objection is empty.



What is an

existence predication — Leontiskos

?

"X will be tomorrow"? What does that mean, other than, "X will be true tomorrow?" — Leontiskos

It's coherent to say 'it is true that the planet will still exist when humanity has become extinct'. Do you think it is coherent to say 'when humanity is extinct it will be true that the planet will still exist'?

They are not saying the same thing; one says it is true now and the other says it will br true then. This is so regardless of whether you think the latter is true and coherent. If you think truth is just a property of propositions then the second sentence cannot be true or coherent. If you think truth is something more than that them the second sentence may be true and coherent but it still doesn't mean the same as the first.

Isn't this just saying that what we know must be consistent? — Banno

It's saying that if "p" does not entail "q is true and not known to be true" then if "p" is true then it is possible to know that "p" is true.

It also looks compatible with the SKP: p↔︎◇Kp — Banno

It's certainly not compatible with that.

SKP entails p ∧ ¬Kp ↔︎ ◇K(p ∧ ¬Kp).

My restricted knowability principle explicitly allows for p ∧ ¬Kp ∧ ¬◇K(p ∧ ¬Kp).

But antirealism in contrast does seem to commit to one or other non-binary theory of truth. — Banno

With respect to counterfactuals, sure. The anti-realist will say that "if Hitler hadn't killed himself then he would have been assassinated" is neither true nor false.

Whereas the realist would have to argue that either it is true or it is false, but then that opens up difficult questions about the reality of counterfactual truthmakers.

I don't see that it counts against realism that it might permit global skepticism. — Banno

If Putnam is correct then global skepticism is incoherent. Therefore if realism permits global skepticism then realism is false.

While the inferences you have used appear correct, I'm not convinced that ]∀p∀q((p ⊭ (q ∧ ¬Kq)) → (p → ◊Kp)) is as helpful to antirealism as you supose.

It's certainly not compatible with that. — Michael

Then you reject "p↔︎◇Kp where p is basic".

∀p∀q((p ⊭ (q ∧ ¬Kq)) → (p → ◊Kp)) — Michael

It's saying that if "p" does not entail "q is true and not known to be true" then if "p" is true then it is possible to know that "p" is true. — Michael

(Shouldn't that be "q is an unknown truth" for continuity?)

It says that if p doesn't entail that there is something we don't know, then we can know p. That's not the same as

The only unknowable truths are "p is an unknown truth". — Michael

If p doesn't entail that there is something we don't know, then it entails that we know everything. And we are back at the start.

p ⊭ (q ∧ ¬Kq)
p ⊨ (p→(q→Kq))

I think there are other more general grounds for rejecting global scepticism than Putnam's argument that reference fails for BIV. But merely permitting global scepticism is not ground for concluding that realism is false: A→(Bv~B)⊭~A

It is difficult to get a purchase on what Leon is proposing.

We have that "the cat is on the mat" is true IFF the cat is on the mat. One hopes that we agree on this, at least. Now I think it is apparent to you and to I that the cat might be on the mat, even were no one around to say "the cat is on the mat". seems to be of an alternate view; that the cat could not be on the mat if there were no one around to form the sentence "The cat is on the mat".

Propositions are strings of words. "the cat is on the mat" is a proposition. It requires all the apparatus of language use in a community. Cats on mats are not strings of words.

I agree. I have no idea what he is wanting to say. So far as far as I can tell his objections have been a series of misrepresentations. I haven't received a response from @Leontiskos to my last post.

Being a theist he could say that the cat is on the mat is true because God is there to judge it to be so. I guess we can say that truth is a property of judgements, if a judgement would qualify as a a kind of proposition, although that question would open up some other issues I suppose.

There would be gold in Boorara, even if there were no folk around to know that there was gold in Boorara. — Banno

Something which can obviously ever be known once it has been discovered. Once it has been discovered, you will know it was there already, but not up until then.

Once it has been discovered, you will know it was there already, but not up until then. — Wayfarer

That, as obvious as it is, doesn't seem to change the fact that it was there already.

'There already' is a concept.

But merely permitting global scepticism is not ground for concluding that realism is false: A→(Bv~B)⊭~A — Banno

The argument is:

R → ◇BIV, ¬◇BIV ⊢ ¬R

Then you reject "p↔︎◇Kp where p is basic". — Banno

Well, ◇Kp doesn't entail p, and so ¬p ∧ ◇Kp is consistent, and not to be confused with ◇(¬p ∧ Kp).

But the anti-realist accepts p → ◇Kp where p is basic.

It says that if p doesn't entail that there is something we don't know, then we can know p. — Banno

That would be ∀p((p ⊭ ∃q(q ∧ ¬Kq)) → (p → ◊Kp)).

I am saying ∀p∀q((p ⊭ (q ∧ ¬Kq)) → (p → ◊Kp)).

As an explicit example of what I am trying to symbolise, if "it is raining" is true then it is possible to know that it is raining, but "it is raining and nobody knows that it is raining" can be true even though it is not possible to know both that it is raining and that nobody knows that it is raining.

If p doesn't entail that there is something we don't know, then it entails that we know everything. — Banno

I don't see how you get to that conclusion. My formulation does not allow for step 2 in Fitch's paradox:

Now consider the instance of KP substituting line 1 for the variable p in KP:

(2) (p ∧ ¬Kp) → ◊K(p ∧ ¬Kp)

But symbols aside:

If something exists then it is possible to know that it exists, and if it is doing something then it is possible to know that it is doing that thing, and if it is not doing something then it is possible to know that it is not doing that thing, and if it doesn't exist then it is possible to know that it doesn't exist – with the same reasoning applied to the past, the future, and counterfactuals.

Nothing here entails that if something exists and is doing something then we actually know it, so if you're concluding from the above that we know everything then you're addressing a misrepresentation.