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.

For me, to find that part where I say, "There's no way of testing this hypothesis," I invent a hypothesis that cannot be tested, and try to think why I cannot test it. Take an invisible unicorn for example. Perhaps there are invisible undectable unicorns that exist. It seems in our head like it could be true. But that's nothing we can actively test in reality, because its undetectable. — Philosophim

Let's try this hypothesis:

On a rocky planet, moon, or asteroid somewhere in this universe we call home, located one kilometer beneath the surface, is a rock formed in the exact shape and size of a 1909 svdb US copper penny.

So, there are ~10^23 stars in the universe. Let's say there's one candidate location in each star system and we can check one location every second, including travel time. Given there have been about 4 x 10^17 seconds since the universe began, that means it would take more than 2 million times as long as the universe has been around to check all the locations. Somebody check my math. Obviously, this is a very, very, very^15, conservative estimate of how long it would actually take.

To me, our hypothesis is neither true nor false. It has no truth value. It is metaphysical or meaningless. I think that's my pragmatist voice speaking.

how do you judge whether a proposition is true or false — SophistiCat

Justification

decidable or undecidable — SophistiCat

That is the question on the table. Here's what I wrote in a previous response to @RussellA.

That's the question I'm wrestling with. I think, although I'm not sure, that there's a standard that has to be met. It's like they say, you can't prove a negative. There has to be a point where I stop and say "We've found no evidence. We can't see any way of testing this hypothesis. That's the best we can do." I don't know if we are at that place yet with the QM multiverse interpretation or, say, string theory. It is my understanding that many scientists think we are. — T Clark

(When you talk about interpretations of quantum mechanics, for example, it sounds like you mean the latter, to the exclusion of any other standard.) — SophistiCat

It is my understanding that all interpretations of QM are equivalent in that they have not been verified and may not be verifiable.

There is good metaphysics, where one reflects on the new findings of science and tries to puzzles together our previous epistemology and the new implications and there is bad metaphysics where one starts from unfounded assumptions/ existential claims (theism, idealism) and ends up with more unfounded assertions. — Nickolasgaspar

I believe that the meaning of "metaphysics" you describe does not represent how that word is normally used in philosophy at the current time. That's what this thread is about.

So, the answer to T Clark's question is yes, a proposition such as "there is a god beyond our comprehension" not only can be true or false but must be either true or false. — RussellA

I don't understand how you reach that conclusion.

In answer to SophistiCat's question as to where does this lead, it leads to the knowledge that there are some things that are beyond our comprehension. — RussellA

I don't agree with that either.

The following are neither true nor false:

1. Cook
2 Kplx zgfd
3. This sentence is false (liar sentence)
4. &×* — TheMadFool

1, 2, and 4 are not propositions. This argument doesn't apply to them. 3, the liar's paradox has always bothered me. @Banno made a similar comment earlier in the thread. I'm still working on a response.

Then, as per you, the following too are neither true nor false:

1. Free will exists
2. God doesn't exist
. — TheMadFool

I think "Free will exists" is a metaphysical question and is neither true nor false. Let's not get into a discussion of the merits of that position right now. I've acknowledged several times in various threads that I am ambivalent about how existence of a specific God or gods fits into metaphysics. It would seem that the existence of the Christian God is a matter of fact, and, thus, not a metaphysical question. Again, I don't want to get into the specifics of this particular issue in this thread.

Am I missing something? — TheMadFool

I don't think your argument, to the extent your response even provides one, has any merit.

This doesn't seem to lead anywhere, because it involves a vicious epistemic circle. Truth or falsity are established in the framework of some epistemic standards. Janus's statement questions one epistemic standard, which is fine, but the resolution will require some other epistemic standards, distinct from the one that is being questioned. — SophistiCat

An example would be helpful if you can think of one.

There may be no evidence today determining the truth or falseness of the multiverse interpretation of QM, but there may be evidence next year. As Philosophim wrote: "Maybe humanity will discover the truth about multiverse theory, and maybe they won't" — RussellA

That's the question I'm wrestling with. I think, although I'm not sure, that there's a standard that has to be met. It's like they say, you can't prove a negative. There has to be a point where I stop and say "We've found no evidence. We can't see any way of testing this hypothesis. That's the best we can do." I don't know if we are at that place yet with the QM multiverse interpretation or, say, string theory. It is my understanding that many scientists think we are.

Then I must be "mind-mindbogglingly arrogant". If I had to choose between a book that contains knowledge and a book that contains somebody's intuitions, I would choose the former. Simply put: it's better to know. — Wheatley

Your response has ignored the content of my post.

So you mean to respect the rights of others. But the pursuit of happiness being one of those rights you have listed, then I don't think we really disagree with each other don't you think ? — Hello Human

I still think we disagree. Pursuing happiness just means living life as you think is best. I've committed to respecting other's right to do that. I don't see that has anything to do with goals or purpose.

PPS__ I apologize for not just going away quietly, but I think this topic is essential. Plus, I really get into this unreal stuff. — Gnomon

I've laid out my whole metaphysics schtick over the previous six pages, not counting all the other places in the forum I've discussed it. I have no desire to go back over the whole thing again. Your understanding and mine are just too different to reconcile. I agree that it's essential, but I've thought about this a lot and I'm comfortable where I stand.

If A is true, then b is true by consequence. But it could happen that tomorrow mankind discovers multiverse theory is true or false. Therefore this proposal is more of a prediction such as, "Tomorrow the sun will rise again." As such, the only thing we can do in this case is wait. Maybe humanity will discover the truth about multiverse theory, and maybe they won't. — Philosophim

Yes, I think you've laid the argument out correctly. You've raised another question in my mind. Here it is:

Since there is no evidence whether it is possible to determine the truth or falseness of the multiverse interpretation of QM, should that interpretation be given serious consideration as a scientific theory?

I want to clarify this. Do you mean we have an idea that we can conceivably prove to be true or false, but we don't currently have the means to do it? Or do you mean an idea that we have no conceivable means of even trying to prove it true or false? — Philosophim

The example I used in the OP may clarify things.

I think the multiverse interpretation of quantum mechanics is meaningless because I believe it is not possible to demonstrate if it is true or false, but, I can't prove it is not possible. Given that, what is the status of the multiverse interpretation.

I started working on a response to your post but quickly started running around in circles. I'm still thinking about it and I'll get back to you later.

PS___See the post by Nickolasgaspar above — Gnomon

Yes, I just responded to it. I included some links to your posts. As I told him, 1) I think there are similarities between your positions and 2) I disagree with both of you.

But such misunderstandings are the fodder for Philosophy. Only in Politics would it lead to retreat or attack. — Gnomon

I don't think there is any way to find agreement between our two positions. I'm certain you won't convince me of your position and I strongly doubt I will convince you of mine. It just doesn't seem likely to be a very fruitful discussion.

So in plain words "Metaphysics" just means: The philosophical work we do AFTER we have finished doing our scientific investigations. Its labels our philosophical efforts to understand what those new scientific data mean for our understanding and what are the implications on our current epistemology and the world. — Nickolasgaspar

This is an interpretation of the meaning of "metaphysics" I've never heard before. Based on the limited amount I have read, I don't find it very convincing.

Any hypotheses of science is nothing more than Metaphysics. Only after we verify or falsify them, they either become Theories(part of our Epistemology) or they are dismissed. — Nickolasgaspar

Even for a word such as "metaphysics," where there is such confusion and disagreement about it's meaning, this seems clearly wrong to me. Your argument sounds a lot like the one @Gnomon was making previously in this thread.

Those are examples of ideas & opinions, which are by definition : Meta-Physical. — Gnomon

Yes, I know Aristotle didn't use that term, but when spelled with a hyphen, "Meta-Physics" denotes the practical distinction between material Science and mental Philosophy : that which is beyond the scope of physical examination, but is amenable to rational scrutiny...

What is metaphysics according to Aristotle? "
Summary Metaphysics. What is known to us as metaphysics is what Aristotle called "first philosophy." Metaphysics involves a study of the universal principles of being, the abstract qualities of existence itself. — Gnomon

I harp on the not-physical implications of "Meta-Physics" in order to distinguish a Philosophical concept from a Scientific topic. Empirical Scientists don't usually concern themselves with abstract concepts, such as Being and Ontology. But posters on this forum often try to place "metaphysics" under the umbrella of physical science, in order to avoid its spiritual implications. Which is why I point-out the second dictionary definition : "abstract theory with no basis in reality." ___Oxford. Can we simply agree that "abstractions" are not Real, but Ideal --- existing only in abstract Minds instead of concrete Brains? — Gnomon

I disagreed with him also.

It is irrefutable that only a consciousness brings the wave function to collapse. — SolarWind

Even if it's irrefutable, that doesn't mean it's true.

I'm sorry that you are frustrated by the lack of progress on this perennial philosophical stalemate. But, this topic is labeled "what is metaphysics. yet again". So, I think it's essential that we at least agree on a clear distinction between "Physics" and "Metaphysics". — Gnomon

I'm not frustrated, I just think your understanding and use of the word "metaphysics" is too different from mine for us to have a fruitful discussion now. As I've said previously, I came to metaphysics with a specific interest in the difference between the idea of objective reality, which I understand as the basis of western science, and the Tao, as described in the Tao Te Ching. Looking at that and similar issues convinced me that the difference between metaphysical positions is not a matter of truth or falsehood, but rather of usefulness in a particular situation. When I came across Collingwood's work, I found it very helpful in finding the right words to describe those differences in a way that I find satisfying.

I guess I don't see any good way to resolve the differences between your way of seeing things and mine.

What do you think is going on? — TheMadFool

Two things. 1) The Mad Fool has a "paradox" obsession; and 2) Having a function is not the same as having a purpose.

What do you mean by respect for a person ? — Hello Human

Jefferson et. al. put it better than I could - I recognize that all people are created equal and that they are endowed by their Creator with certain unalienable rights and that among these are life, liberty, and the pursuit of happiness.

I think that whether or not something whose truth value is undecidable nonetheless may be true or false, is itself undecidable. — Janus

I think I may want to start a new thread just for this statement.

I think that whether or not something whose truth value is undecidable nonetheless may be true or false, is itself undecidable. — Janus

My, aren't you clever. Nicely put.

I think you and I have taken this as far as we can for now.

That we cannot definitively answer such questions I would agree, but that there is no truth of the matter I don't have a settled opinion about. — Janus

I'm not even sure we are disagreeing. — Janus

So I guess here's the real difference in our views - As I see it, if we cannot definitively demonstrate the truth of a proposition, even in principle, then it has no truth value.

If all he means is that their truth cannot be questioned from within the systems that they are foundational then I would agree. Do you think he wants to claim more than that? — Janus

Good question. I think he means that but also more than that. I'll have to think about it some more.

Anyway it has been interesting and somewhat (which is probably the best we can hope for) clarifying; so thanks. — Janus

It has been more than somewhat clarifying for me.

I don't think 'true' is the right word; useful or valid would be better. — Janus

This is the way I would say it too - Not true or false, useful or not useful.

I have read Collingwood's book and I still don't really understand what it could mean to say that metaphysical propositions or axioms are not true or false — Janus

I'd like to try to run through a thought experiment. I'm not trying to set you up for anything. I'm not even going to try to convince you of anything. I just want to see if I can get to the heart of our disagreement.

How would you characterize your philosophical understanding of the nature of reality? Realism, materialism, idealism, physicalism? Is objective reality all there is? Is reality just information? Is it just an illusion that only exists in our minds? For me it's easy - I'm a pragmatist, which means you can't tie me down to anything. When I was young, though, I was a strong materialist. Wore the label proudly. It seemed self-evident to me that the world is just the physical stuff that we interact with.

Now - is there a philosophical understanding that you reject strongly? For me it was always idealism. The idea that basis of reality existed on some sort of higher plane not accessible to us seemed deluded.

I guess by your way of seeing things, your chosen philosophical viewpoint is true and the one you reject is false. Is there any objective or even convincing way for us to resolve the issue and prove that one is correct? Obviously, from where I stand there isn't.

I don't really see that running through this will resolve the disagreement we have, but I thought it might be interesting.

Of course, ideas & opinions have a physical substrate, but the neurons themselves are meaningless. So, my comment was directed at the subjective meaning, not the objective container. — Gnomon

Yes, I also am talking about meaning, not the physiology of nervous system.

I don't believe your understanding that all mental phenomena are considered metaphysical is consistent with any generally accepted definition of the word. I don't see any way to reconcile my understanding of the word and yours. I guess we'll have to leave it at that.

Those are examples of ideas & opinions, which are by definition : Meta-Physical. But are they "rules" or "laws" governing subjective reality? — Gnomon

Some thoughts:

Ideas and opinions are not "by definition" metaphysical.

In the OP I described my view of metaphysics as the "...set of rules, assumptions we agree on to allow discussion, reason, to proceed..."

I also like Collingwood's definition:

Metaphysics is the attempt to find out what absolute presuppositions have been made by this or that person or groups of persons, on this or that occasion or groups of occasions, in the course of this or that piece of thinking.

even professing the absence of necessity for a meta-framework is a type of meta-framework, — Olivier5

Did you think I ever professed "the absence of necessity for a meta-framework?" I never did.

Hey, you're just supposed to tell me when I'm a jerk and tell us about Russia. You're not supposed to give me substantive responses to my posts... Actually, this is a really good response. Makes me think.

But from the point of view of a kind of Kantianism--particularly Schopenhauer's--these two are consistent. At least, they're consistent if science's objective reality is not taken as the ground of being. — jamalrob

Hm... I am aware that many western philosophers have a concept similar to the Tao. Kant's "thing in itself." I've heard that Schopenhauer does too. I've been rereading Collingwood's metaphysics essay. In his discussion of Aristotle's metaphysics, he describes the concept of "pure being," which has a lot in common. One of my favorite refrains - There is only one world. Add to that we are all human. Of course there will be parallels between philosophical systems.

science's objective reality is not taken as the ground of being. My guess is that this is quite a common stance even among scientific people. — jamalrob

I don't think this is true. I think scientifically oriented people do see objective reality as the ground of being, to the extent they've ever thought what "ground of being" means or if it exists. You certainly see that here on the forum a lot.

You know the story: we perceive and model the world in the way we do owing to the way that we must do according to our perceptual and conceptual faculties. We never get beyond that to see the world in itself, the ground of being. What we have then, and what we study scientifically, is empirical reality, i.e., real and objective but bound reciprocally with human beings. (Whether this is coherent or not is another story). — jamalrob

You say "...we perceive and model the world in the way we do owing to the way that we must do according to our perceptual and conceptual faculties." I think that's similar to what I mean when I say that there is only one world and we are all human. If you're saying that all philosophical systems have to be consistent with each other, I'll probably agree with you. In a sense, you're restating my premise. If they're all the same, we get to pick what's best for us. Yes, I know that's not what you're saying. At least it's not what you think you're saying.

How is empirical reality different from objective reality? Actually, I can see how they're different, but I don't think many, most, materialist (physicalist, realist) minded people do.

It was Schopenhauer who took it a step further and asserted positively that the thing in itself, that which is beyond human perception and concepts, is an undifferentiated unity. He might have been encouraged in this by his reading of Eastern philosophy. — jamalrob

As I noted, it is my understanding that this idea is not uncommon among philosophers. I was reading about noumena once and it struck me how similar they are to the Tao, so I checked on the web. I found a paper that compared the two concepts. It wasn't a very good paper, but the idea is out there.

So it seems to me that it doesn't necessarily follow from one's ability to hold both positions at the same time that they are neither true nor false. — jamalrob

Hm... (again) People have been arguing materialism vs. idealism for thousands of years. If one is right and one is wrong, tell me which is which. If which one is true is an open question, tell me how that question get's resolved. I just read somewhere recently that mathematicians tend to be idealists while scientists tend to be physicalists. Whether or not that's true, it's at least plausible. And that doesn't even address all the other isms out there.

They might be doing different things, and are true in their own ways, meaning at their own levels of description or within their own scope. — jamalrob

I'm not certain that's different from what I'm saying. As Collingwood wrote:

Metaphysics is the attempt to find out what absolute presuppositions have been made by this or that person or groups of persons, on this or that occasion or groups of occasions, in the course of this or that piece of thinking.

Is that different from your comment?

Good comments. Made me work a bit. This was fun.

respecting those preferences is the same as respecting their goals. — Hello Human

First of all, no. Preferences are not the same as goals.

And then - I believe that all people are created equal and they are endowed by their Creator with certain unalienable rights. That among these is the right to life, liberty, and the pursuit of happiness. Approving their choice for what's required for the pursuit of happiness is not necessary. That's sort of the point.

It's not respect for the other person's preferences that's important, it's respect for them.

the term is essentially meaningless, meaning whatever anyone wants it to mean. — tim wood

As I've noted, this is what I've come to think is true.