the direct realist wants a stick with which to beat his opponent on some matter of dispute and "it's objectively the case that..." makes a great stick — Isaac

In my example, the challenge is "try it and see", which still strikes me as an epistemically healthy attitude. Does saying that make me a realist? What if I say some magic word like "objective"? Or does the demand for verification make me an anti-realist?

Mathematics is really curious in this way. Mathematicians lean toward Platonism because of experience: it feels like you're discovering patterns and structures in something that is there; you invent tools to explore with, but you have to make them out of things that have already been found. On the other hand, "truth" in mathematics, as a practical matter, means "proven". Until there's a proof, all you have is a conjecture. Fermat's Last Theorem didn't count as true, despite most mathematicians' intuition that it was, until we got the proof.

In what sense are structures, as distinct from matter, mind-independent? — Michael

Scientific sense? The fluid dynamics of Heraclitus' stream are discovered, not built as with a ship.

Realism argues that truth is recognition-transcendent and bivalent. — Michael

Poor me! I think it is recognition-transcendent but not bivalent. Am I a semi-realist?

In what sense are structures, as distinct from matter, mind-independent? — Michael

Matter always takes a form, so structures are important characteristics of any material object. It's not independent of matter, it IS matter. The shapes that matter takes. In this sense, structures are objective realities, they exist whether you recognise them or not. A tiger does stop to be a tiger and morph into something else, like a pig or a tree, when you don't recognize it.

Are you a Platonist?

No.

And in what sense do two different sets of matter have the same structure? And not just the same type of structure, as in the case of the twin ships built to the same specification, but the same token structure, such that the ship that leaves is the same ship that returns (i.e. not just a copy of the original)?

Two atoms of hydrogen or two molecules of water have the same structure, isotopes aside. They are impossible to distinguish from one another and therefore they are functionally the same thing.

Two atoms of hydrogen or two molecules of water have the same structure, isotopes aside. They are impossible to distinguish from one another and therefore they are functionally the same thing. — Olivier5

But even my six-year old knows when I've drunk from her glass of water instead of mine. Otherwise fungible things are rendered discrete from one another by virtue of context.

EricH joined in with a roughly constructivist - and hence anti-realist - account of mathematics. — Banno

Just for the record I was merely describing this account of mathematics. I have no opinion/thoughts one way or the other - it's way above my pay scale. :razz:

As long as it's in front of her and she can keep it there, yes, it becomes functionally different by way of being meant for her use and not yours, although tomorrow she may drink from another glass with no way to know which is which.

Right. So in what cases does the dubious know-ability of reality come in to play? Is it a model you often use to counter the argument of your fried Bob, that he can fly to the moon? I'd wager no. It's a model used to counter the argument of Bill that he can lift 170kg if he believes he can. "No, your belief doesn't make something real, you either can lift 170kg or you can't" Of course you may already know about the placebo effect and so not counter this way, but this is about the effects you don't know, not the ones you do. — Isaac

If your point is that there is minimal practical import to the questions posed in this thread, I think it's obvious that most navigate the world successfully without philosophical contemplation at all, particularly without ever challenging fundamental assumptions about reality. What this means is that the answer to your specific question is that I would respond to Bob whether he could fly to the moon in the way we all would in the normal world, but if he were posing the question in this thread as it related to challenges to realism, I would point out that we must first establish the correlation between perceptions and reality before discussing the moon and the physical properties he believes he has deciphered from his perceptions.

In any event, your argument is the "appeal to the stone" fallacy which was named after the following event:

"After we came out of the church, we stood talking for some time together of Bishop Berkeley's ingenious sophistry to prove the non-existence of matter, and that every thing in the universe is merely ideal. I observed, that though we are satisfied his doctrine is not true, it is impossible to refute it. I never shall forget the alacrity with which Johnson answered, striking his foot with mighty force against a large stone, till he rebounded from it, "I refute it thus."

— James Boswell, The Life of Samuel Johnson

https://en.wikipedia.org/wiki/Appeal_to_the_stone

Anti-realism argues that truth isn't recognition-transcendent and/or truth isn't bivalent. Realism argues that truth is recognition-transcendent and bivalent. — Michael

Provide an example of a statement that is both true and false. Are you saying within exact contexts and with exact definitions the same statement can be both true and false?

Provide an example of a statement that is both true and false. Are you saying within exact contexts and with exact definitions the same statement can be both true and false? — Hanover

The ship that leaves is the ship that returns.

Although my main support of anti-realism is in the rejection of recognition-transcendent truth conditions rather than the rejection of bivalence.

The ship that leaves is the ship that returns. — Michael

But that involves telling a story, it's not providing something simultaneously true and false.

While functionally we likely agree, there is this amusing thought about how it could be that there is but one particle in all of reality that constructs everything we understand as real. If there is no way (in principle, theory, fact, etc.) to establish the identify of something by reference to its context, then the omnipresent particle becomes the simplest explanation.

Random article about the idea on a much smaller scale (who said philosophy is useless?). Giant Molecules Exist in Two Places at Once

I don't know what you mean. It's a statement about the ship that leaves and the ship that returns. It doesn't have a single truth value.

Other possible examples are statements about the future (especially if there is free will or some things are actually random) and counterfactuals, although in these cases it's not that they're both true and false but that they're possibly neither true nor false.

Take out the word "objective" and we're not talking about realism anymore. — Michael

I don't see why. There's this:

realism holds that ...stuff... is independent of what we say about it; anti-realism, that it isn't. — Banno

Nothing in there about the objective-subjective divide. A realist can agree that the ship's components have changed and maintain that we can use the same name for the ship. Indeed the whole ship of Theseus argument seems to me pretty irrelevant to the discussion at hand, for reasons given above.

Realists need not deny that there are social conventions. Nor that social conventions are all reducible to physical facts - that'd be physicalism.

I don't know what you mean. It's a statement about the ship that leaves and the ship that returns. It doesn't have a single truth value. — Michael

Just my thinking through this - I may well be wrong. I thought we were looking for things that were true and false simultaneously. For your idea to be 'true and false' you require a narrative description because the departure and arrive are two separate events over time. Would this not be the same thing as saying a human being is both young and old? Age can be visualized as a journey similar to your ship idea.

A realist can agree that the ship's components have changed and maintain that we can use the same name for the ship. — Banno

I'm not saying that we use the same name for the ship. I'm saying that it's the same ship.

The ship that leaves is the ship that returns. — Michael

It has but one truth value unless you've got an equivocation fallacy. "Ship" must vary in meaning in order for "the Ship is X" to be true and false in differing contexts. Or, are you saying "X and not X" is not a contradiction?

It has but one truth value unless you've got an equivocation fallacy. — Hanover

It doesn't. If you say that it's the same ship and I say that it's not the same ship then it's not that one of us is right and one of us is wrong.

doesn't. If you say that it's the same ship and I say that it's not the same ship then it's not that one of us is right and one of us is wrong. — Michael

That means it has no truth value, not that it has a true and false value. Is it a non-propositional statement, like "Hello there!"

I think you have a very strange understanding of language if you think that when I say that the ship that returns is the ship that left that I'm not asserting a proposition.

The person who is born is the person who also dies. Does this mean it is true to say that a person is both born and dead? Isn't this how the ship departure/arrival functions?

Cheers. The mathematical notion of truth you provided gives us a clear picture of anti-realism. And you mention the rejection of the notion that all truths are knowable, which is central to realism.

EricH Cheers. — Banno

He gets a "cheers" and I get to envy the size of your lunch. Bloody favoritism.

For your idea to be 'true and false' you require a narrative description because the departure and arrive are two separate events over time. Would this not be the same thing as saying a human being is both young and old? — Tom Storm

It doesn't require a narrative description, but your example of a person being both young and old is a good example. "Young" and "old" don't have a clearly defined age-range. Is someone who's 40 young or old? A 10 year old and an 80 year old will likely disagree, and as a young-at-heart 33 year old I'm on the fence. But it doesn't make sense to say that one of them must be wrong, or that I must commit to one side or the other (which would be the case if the principle of bivalence holds).

Peter van Inwagen, if I recall correctly, proposed (in Material Beings) the idea that only living things have an identity. — Srap Tasmaner

Yes. this is exactly the point I made in my last response to your question about the identity of the caterpillar and the butterfly..

The import here is that of a word game, perhaps; the reason for this thread is to explore the relation between several recent topics, including logical nihilism, Davidson's use of T-sentences, Anscombe's direction fo fit and a few other items, together with an exploration of when and where to apply realism or antirealism. A bit of subtlety is needed, but the thread is in danger of being overrun by vatted brains, as is want to happen when the topic is raised.

I find Johnson's reply quite convincing. A showing rather than a stating.

That means it has no truth value, not that it has a true and false value. Is it a non-propositional statement, like "Hello there!" — Hanover

A better approach for @Michael might be to adopt a trinary logic; instead of claiming that it is the same boat is both true and false, claiming that it is unknown or undecided. Then at least there would be some formal logic for him to make use of. This might be what he has in mind.

I'm not saying that we use the same name for the ship. I'm saying that it's the same ship. — Michael

What, specifically, is the difference between these?

Thinking on @Michael's notion that a statement can have two truth values.

it's not paraconsistent logic - which holds that A, ~A ⊨ B is not a valid inference; this is the view usually associated with anti-realism.

it's not quite dialetheism, which holds that for some A both A and ~A can be assigned the value "true". - that there are true paradoxes.

It's something new, is seems - at least to me: that a statement can be assigned more than one truth value.

Are there precedents?

? ?

doesn't require a narrative description, but your example of a person being both young and old is a good example. "Young" and "old" don't have a clearly defined age-range. Is someone who's 40 young or old? A 10 year old and an 80 year old will likely disagree, and as a young-at-heart 33 year old I'm on the fence. But it doesn't make sense to say that one of them must be wrong, or that I must commit to one side or the other (which would be the case if the principle of bivalence holds). — Michael

This isn't a rejection of bivalence. This is just pointing out certain words are vague. If the law were only old people are allowed to enter and old is defined as over 40, then that's just a clearer form of language.

What you're getting at is much more than this. You're claiming that what a 40 year old is cannot be determined because there is no single truth value to the statement "a 40 year old is X."

Cheers.