...pointing out that whether one assigns true or false to this sentence, it must be undecided, and hence it is a candidate for an example fo the sort of sentence you asked for. — Banno

If something's truth value is undecided that doesn't mean it isn't true or false, only that I don't know. On the other hand, if it's truth value is undecidable, I consider it either as having no truth value or as being meaningless.

I think we've gone far enough with this. I don't see that any more back and forth will bring us any closer to agreement.

But that makes no sense. — Banno

You wrote:

Seems to me we can assign "true" or "false" to the above sentence without contradiction, so the answer is "yes, there can be sentences that are true or false but undecidable". — Banno

I say - Whether or not you want to assign truth value to the referenced sentence is a matter of your choice, taste, value, preference. It's not a matter of fact. I, when I'm wearing my pragmatist boots, would say no. That would be a matter of my choice, taste, value, preference.

Whether or not you agree with that, it shouldn't be hard to understand.

Sometimes ya gotta do what ya gotta do. And no bluff. If I'm president, I share with the Chinese that if they invade Taiwan, then we're all in. And naturally there are lots of reason not to fight that can be appealed to.

Maybe more interesting is what happens if the Russians try to annex the rest of Ukraine. — tim wood

This is the kind of thinking that lead to Vietnam, Iraq, and all sorts of other disastrous American military actions. Who says we gotta do anything militarily in Taiwan or Ukraine? You and John Bolton I guess. Sometimes you shouldn't do what ya don't gotta do.

You could consider that a disputable meta-metaphysical claim. I would be quite happy to defend it. — apokrisis

I think you and I are in agreement.

Can human things be described by having a cause that is neither nature nor nurture? If so, what? — TiredThinker

I'm not sure what you mean by a person having a cause. I think it is clear to say, though, there is a human nature that is independent of our experience in the world. We are not born as blank slates. We have inborn capacities, tendencies, instincts, temperament. There is plenty of science to show this. One of my favorite refrains, not based on science but on my experience with my own children - Babies come out of their mothers fully the people they will always be.

That still leaves plenty of room for experience in the real world, nurture, to have it's effect on our lives and our minds.

A small point of jargon. But important where folk are mostly arguing rhetorically.
— apokrisis

I'm not sure "rhetoric" is the right word. They're not just trying to convince you of their position, they actually believe in the truth of what they say and are trying to present their position.

Anyway, the difference can be summed up that by saying the principle of bivalence is the logical claim that propositions are to be judged either true or false - true or not true. And a dialectical or dichotomous logic says that any "bivalent" division of metaphysical possibility has to obey the rule of being "mutually exclusive/jointly exhaustive". So to be "true", each has to stand as the logical negatation the other. Or to be more accurate, each has to be the formal inverse of reciprocal of the other.
— apokrisis — T Clark

I posted this before I was finished by accident. Let's try again:

Although I agree with your point about how bivalence works, I think there is a place for it as long as you recognize that it is just a point of view, a choice, and not the fundamental basis of reality. I guess that's what you mean when you say:

Reductionism is fine too. It works really well if you want to build machinery or even mechanise human society and the human mind. Simple cause and effect thinking is neat little everyday tool of thought. — apokrisis

What do you think metaphysics ought to deliver as its social good? Does it have a purpose? I can't see any other reason to "do metaphysics" except to attempt to deduce the truth of reality from first principles ... and so set yourself up with clear hypotheses worth the effort of empirical test. — apokrisis

For me, there is no "truth of reality." There are lots of ways of seeing reality. You can choose the one that's most useful in a particular situation, then switch to a different one when the situation changes. I see philosophy, metaphysics, as a tool box. Pull out the right tool for the job.

A small point of jargon. But important where folk are mostly arguing rhetorically. — apokrisis

I'm not sure "rhetoric" is the right word. They're not just trying to convince you of their position, they actually believe in the truth of what they say and are trying to present their position.

Anyway, the difference can be summed up that by saying the principle of bivalence is the logical claim that propositions are to be judged either true or false - true or not true. And a dialectical or dichotomous logic says that any "bivalent" division of metaphysical possibility has to obey the rule of being "mutually exclusive/jointly exhaustive". So to be "true", each has to stand as the logical negatation the other. Or to be more accurate, each has to be the formal inverse of reciprocal of the other. — apokrisis

I think it's a question of values.
— T Clark
I don't see how. — Banno

Would it make more sense to you if I changed "values" to "preference" or "taste?"

It is the same problem that goes back to Kant's phenomenon and noumenon. Kant proposed that a phenomenon is a perceptive representation of an object existing in the mind of a perceiver, rather than the object in itself, the noumenon. Kant did not argue that the world of the noumenon does not exist, for there to be an appearance, there must be something for there to be an appearance of. It is just that human knowledge of the true nature of the noumenon is impossible, as the true nature of the noumenon is always mediated by the senses. In that, for example, we perceive the colour red, we don't perceive a wavelength of 700nm. — RussellA

I was going to say your analogy, comparing the multiverse to noumena, is not applicable, but I thought about it more. I think it is a good analogy. I started this thread to discuss things like the multiverse and my belief that, if I can't know, demonstrate, whether or not it exists, it's existence has no truth value or is meaningless.

I don't think you will find my solution to the issue satisfying - in my view, noumena don't exist either. They are just one way of looking at reality, similar to Lao Tzu's Tao and in contrast to the idea of objective reality.

I assume you mean armed conflict. I do worry. The obvious place where it could happen is in Taiwan. I don't think we should have a commitment to intervene militarily in any conflict there. It's not worth it. That's how World War 1 started. And Korea and Vietnam and maybe Iraq.

On the other hand, I see China's behavior as pretty similar to what the US does and has done. We like to throw our weight around, even to the extent of undermining legitimate governments and starting wars on flimsy pretexts. China is surrounded by potential conflicts much more than the US is. The US has to figure out how to get along in a world with more than just one big boy. More than just two. Lots of countries are starting to grow up economically. I think that's a good thing, but the US will have to learn some humility.

Let's say John has some life goal, becoming a famous singer. Now he uses his time in this world (his life), to achieve that goal, which means his life is an efficient cause towards a final end. — Hello Human

As I noted, I never said no one has life goals or that people shouldn't have them, only that I don't.

Which is why my views on morality are based on respect for others' happiness. — Hello Human

I see two parts to morality as we are discussing it 1) Respect for, not other people's happiness, but their right to pursue happiness in their own manner and 2) Compassion.

Really? It's an obscure bit of truth theorizing. — frank

Maybe it just comes up in a lot of my discussions.

A statement/proposition is a sentence that's either true or false. — TheMadFool

I told you yesterday that this is not true, but I was wrong, at least according to Collingwood. Yes - a proposition has to be true or false. An absolute supposition has no truth value.

You need to go over what you said above carefully, specifically the parts underlined. — TheMadFool

I think I've gone through this enough for now.

I edited it. — Wheatley

Thanks.

I understand her philosophy is quite controversial so lets stick to defining her objective claims and avoid critiquing it.
— OscarTheGrouch
FYI: There are no rules about obeying the wishes of the OP. — Wheatley

Re you response to @OscarTheGrouch

I strongly disagree with your statement about the requirement to follow the OP. For that reason, I copied it to the Shoutbox and asked the moderators to respond.

Rand is not a popular philosopher here on the forum. You may have trouble getting a helpful response, for example:

I read one once, but I have almost completely recovered. There is still hope for you, but try not to talk about it so much. — unenlightened

I have read three of her books, all fiction - "Atlas Shrugged," "The Fountainhead," and "Anthem." All are badly written. I find the philosophy woven into the story distasteful, unconvincing. I have also read a bit about her philosophy and life. For me, a little bit of illogical reasoning is the least of her problems. I think her complete misunderstanding of and contempt for human values is hard to get past.

Sorry I can't help. Welcome to the forum.

My explanations transcend words and intellect. You will only understand them when you are ready. — Miller

[joke]If I may translate "Because I said so."[/joke] Not a very convincing response.

Welcome to the forum.

I believe a large part of philosophy is figuring out what we should spend our efforts on pursuing in reality. — Philosophim

I agree strongly. Turns out you're a pragmatist too. Welcome.

Technically I would say "It may be true or false, but it is extremely likely that it is unknowable." It may just happen that the first planet you look at contains the penny. Extremely unlikely, but not implausible. But that is the way I see truth and falsity. They are independent of our knowledge. — Philosophim

Keeping in mind that I vastly underestimated how long it would take to find the rock/penny. Even in our solar system there are probably hundreds of rocky entities two kilometers in diameter or greater. Even if it's on earth, how long would it take to check. If it's in another star system, it would take decades at least to reach it. Unless someone invents faster than light travel, we couldn't ever reach most systems.

I say, at some point, when something becomes too difficult to verify, it loses it's truth value. That's the pragmatic view - If the truth of a statement has no possible impact on the world, it 1) has no truth value or 2) it is meaningless. Maybe those two are the same.

Sure. Truth is independent of knowledge. The statement "The capital of Botswana is Georgetown," certainly has truth value, even though you don't know if it's true. From a pragmatic point of view, who gives a s**t, and if no one gives a s**t, it ain't true.

I recognize many people disagree with this view. As Aristotle said, or was it Kant, "Hoo boy, metaphysics is a bitch."

We have the concept multiverse, but if we can never know even in principle whether multiverses exist or not, our concept of multiverse must remain fictional, as a unicorn or Conan Doyle. — RussellA

I agree with this. Many people, including some in this discussion, do not.

A statement/proposition is a sentence that's either true or false. — TheMadFool

Merriam Webster says a proposition is "A statement to be proved, explained, or discussed."

MW says a statement is "Something that you say or write in a formal or official way : something that is stated."

The Stanford Encyclopedia of Philosophy says, "Propositions, we shall say, are the sharable objects of the attitudes and the primary bearers of truth and falsity."

So, whether or not a proposition has to be true or false is an ambiguous question. Still, it's clear from the context that, for the purposes of this discussion, propositions do not have to be true or false. You're the one playing with language here.

I guess your point is truth is not the only game in town. — TheMadFool

I think truth is over-rated, but I can talk truth when it's called for. It can be a useful concept. Hey, wait... I think that's metaphysics.

In this particular discussion, I'm trying to use "truth" as it is normally used in philosophical discourse.

But history has shown that dialectical and trialectic reasoning - a move towards holism - actually deliver the better results when it comes to the forming of general intuitions. Reductionist predicate logic is what you use more in the next step of forming deductive statements that are then suitable for a process of inductive confirmation, or the experimental test of a bivalently-framed prediction. — apokrisis

What is the difference between "dialectical" and "bivalently-framed?" Is it that with the dialectic, the goal is to reach consensus, while with bivalently-framed, we have to make a choice?

So one thing that is clear to any logical holist is that yes/no thinking lacks sufficient sophistication. You need further categories - a third option as an answer, such as yes, no, or vague. — apokrisis

If I understand you correctly, I think I agree. I'm not a big fan of the idea of truth, but for most people interested in philosophy, it is one of the central questions. In this discussion, I'm trying to argue in terms of how the word is commonly used.

Pragmatism builds that answer in. The theory makes some kind of reductively bivalent claim about reality. It is a good thing to be clear in this way. But then the theory is only ever deemed verified or falsified provisionally. The evidence might lean heavily on way or the other. But always, the fact is that there remains something ambiguous or indeterminate about its truth status. — apokrisis

That's why I'm so attracted to pragmatism as a way of approaching the world. I am self-aware enough to see that has as much, or more, to do with temperament as it does with reason.

Then when it comes to quantum theory, we find ourselves bumping up against the fact that nature itself must have this same kind of logical holism. The vagueness that we need to include in our epistemic methodology becomes also a useful third category when we speak of nature “in itself”. — apokrisis

I am skeptical of bringing physics into metaphysical arguments. It's often a symptom of wrong-headed thinking. Is that there one of them "category errors.?" Quantum mechanics seems to be a prime candidate for this mistake. I don't think that's the case with you, but I don't get it.

Your purpose is to be — Miller

Sorry, just like I responded to @Hello Human above, you're just trying to jam additional meanings into the definitions of words.

Seems to me we can assign "true" or "false" to the above sentence without contradiction, so the answer is "yes, there can be sentences that are true or false but undecidable". — Banno

I don't agree, but I don't think we can resolve our differences. I think it's a question of values. I keep ducking into phone booths (What's a phone booth?) and slipping into my Pragmatism Man costume. Yes, it's true, I am a superhero. Motto - "If I can't use it, who gives a fuck if it's true? If I don't give a fuck if it's true, it's not true." Long motto. Lousy, foul-mouthed superhero.

Very little. There are, after all, other things which we not only don't know, but can't know. But we muddle on. — Banno

Australian Pain-in-the-Ass Man's motto may be "Muddle on," but we Amurcan superheros are made of stronger, non-metric stuff.

We can't determine if Caesar stepped into the Rubicon with his left foot. But undoubtedly he either did or din't. — Banno

Little known fact - the phrase "jumping in with both feet" was coined based on Caesar doing just that at the Rubicon according to Roman historian Quintus Fabius Pictor's account.

Living life as you think is best implies living as you want to as long as it does not harm others. You have some ideal and you try to achieve it. That seems very much like a goal. — Hello Human

Seems like every time I disagree with your point, you just go around trying to streeeetch the meaning of "goal" and "purpose" to fit. I may have goals in my life, but that doesn't mean my life has a goal. Actually, the older I get, I find I don't really have any goals in my life either, but my point stands.

I have no objections to you having a goal for your life, but what's true for you isn't necessarily true for others. People are different.

I'm not sure why anyone would define metaphysics in any other way. — TheGreatArcanum

And yet they do.

Discuss as in determine who's right? Or just to understand the diverging narratives? — frank

I don't think there's a right or wrong here. I'm just trying to get my head around the issue. It's something that comes up a lot in discussions.

I’m saying that the term ‘metaphysics’ has a scope, defined originally against Aristotle, developed by the subsequent tradition. Tao Te Ching falls outside the scope. As does Vedanta and Buddhism. Which is not to say that those texts and traditions don’t deal with some of the same subjects, but they do so in very different terms, different languages and different cultural tropes. When you try and combine them all into some grand meta-subject called ‘metaphysics’ then you loose a great deal of specificity which is why you can’t find any criteria for deciding their truth or falsehood. — Wayfarer

I don't think your understanding of the meaning of "metaphysics" is consistent with how the word is generally used in philosophical discussions. It certainly isn't consistent with how I use the word.

Ok, I'll leave off that - seems the thread is headed off into pragmatics anyway. Let me know what you decide about the undecidable sentence in my first post. — Banno

I just posted my response, which was basically just me giving up.

Can a statement be true or false if it is not possible to determine which it is, even in principle?
— T Clark

Can such a statement be constructed?

"This statement is true or it is not possible to determine that this statement is true". — Banno

I don't generally find the liar's paradox very helpful in sorting things out, but I'll take a shot.

Let's start with "This statement is true," and see where that gets us. My intuition tells me 1) It can be decided whether or not the statement has a truth value and 2) The statement has no truth value. I'm not sure I can justify either assertion.

The problem is caused by the sentence's self-reference. Let's try out a couple of self-referential sentences that do have truth values:

"This sentence has five words." - That's true.
“This sentence has seven words.” That’s false.
"This sentence has an unknown number of words." - That's false. I think.

Sorry, I’m not getting anywhere. I don’t think the liar’s paradox is central to my thoughts about the decidability of the truth value of propositions, but I’d like to figure it out. I’m putting it on my list for a separate thread sometime.

At the least we need a way of distinguishing your mooted statements that are neither true nor false from other sentences that are mere nonsense - not even either true or false. — Banno

Why don't you and @TheMadFool take that on. It isn't really relevant to the issues I'm interested in this thread.

Otherwise the claim that metaphysics is nonsense rings hollow. — Banno

I never said that metaphysics is nonsense. Your just trying to be difficult.

In practice, decidability is a pragmatic exercise. — apokrisis

I agree, although I'm not sure I mean the same thing by that statement as you do.

I would say that while we can model the world as if it has counterfactual definiteness all the way down - and so is seems that bivalent logic ought to apply - in fact Nature I only admits to being relatively divided. This makes it vague or indeterminate at base. — apokrisis

Do you mean that as a scientific statement in relation to quantum indeterminism or a metaphysical statement about truth and falsity in general.

(especially if the Tao te Ching is taken as a metaphysical text, which it is not.) — Wayfarer

Of course it is.

The notion that metaphysical statements are neither true nor false won't bare a load. Metaphysical statements are taken as true, but unjustified. — Banno

Needless to say, I disagree.

Too, T Clark hasn't really said anything about how metaphysical claims aren't true or false. — TheMadFool

I've said more than enough about how metaphysical claims aren't true or false. Which isn't the same as saying I've convinced you or others.

Refer back to "What is metaphysics? Yet again." That thread has taken that question about as far as I am interested in taking it right now. This is a new question, a new thread.

neither true nor false is a contradiction — TheMadFool

No, it's not.

T Clark's stand on metaphysical claims is very Buddhist. — TheMadFool

No, it's not.

Depends on how truth is understood. Some will insist that there can be no use to asserting a proposition whose status is unknowable, so it's just a bad question.

A realist might be bound to say there is a use for this sort of thing. — frank

Yes, this is the issue I started this thread to discuss.

Well, that doesn't say much. Justification for whom? Just you, or "us" (as in your response to RussellA), or some kind of objective justification (if that's not an oxymoron)? And what kind of justification? — SophistiCat

This is not intended to be a discussion about what constitutes justification. I would enjoy participating in one if you start it. So, I'll punt - by whatever standard of justification we can agree on.

Interpretations of QM are equivalent with respect to a particular epistemic standard: that of being empirically distinguishable. — SophistiCat

Yes, that's what I meant when I wrote that all interpretations are equivalent.

But some people prefer one interpretation to another, even while acknowledging that they are empirically indistinguishable. — SophistiCat

In my judgement, interpretations that are empirically indistinguishable are the same thing. Differences between them are meaningless.

How do you distinguish non-propositions from metaphysical claims? — TheMadFool

I'm not interested in going into that. Perhaps someone else will.