1) Can a statement be true or false if it is not possible to determine which it is, even in principle? Then, if we can decide that question, 2) What happens if we can't determine if the truth of a statement is decidable in principle or not? — T Clark

If it is not possible to determine even in principle whether the proposition "a multiverse exists" is true/false, then the first problem is not whether the proposition "a multiverse exists" is true or false, but what does "multiverse" mean.

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.

IE, if we can never determine even in principle whether the proposition "a multiverse exists" is true or false, then the "multiverse" must remain a fictional entity, as a unicorn or Conan Doyle.

I think that the truth-status of such conjectures is undecidable; that is I can't decide whether we should say they could be true or false, or that they cannot be true or false. — Janus

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.

At that point, we make a judgement call. Do we potentially spend countless time and money on something that is likely outside of our reach? I believe a large part of philosophy is figuring out what we should spend our efforts on pursuing in reality. If someone tells you to live a certain life, is that reasonable to do so? Should we fear death? How do we know things? Is it reasonable to search for that unicorn?

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.

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.

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.

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."

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.

physics is observing experimental results. Metaphysics is considering what they mean — Wayfarer

Yeah, nah. :smile:

Physics practices its own winning brand of metaphysical world-modelling. It gets on with what it believes works.

Philosophy of science might then critique that.

IE, if we can never determine even in principle whether the proposition "a multiverse exists" is true or false, then the "multiverse" must remain a fictional entity, as a unicorn or Conan Doyle. — RussellA

The difference is that we know that fictional entities we have created for our diversion are fictional entities; we know they don't actually exist. We have imagined the multiverse as a possibility; we have no way of determining if it is an actuality; which is to say we have no way of knowing whether the proposition 'the multiverse exists' is true or not. So, my question is as to whether we can even sensibly speak of the multiverse in terms of being actual or not actual.Intuitively, of course, it seems we can; but if that's right then we do think that untestable conjectures can be true or false. So we think they can be true or false, but can they really be true or false, or is that question incoherent?

Physics practices its own winning brand of metaphysical world-modelling. — apokrisis

Ain't metaphysical, by definition. Physics is not metaphysics, otherwise what would be the point of having a separate subject area? Metaphysics raises its head over the interpretations of what physics implies - many worlds, etc. Physics is 'shut up and calculate'.

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? — T Clark

Bivalence is a reduction to two options. That sets up the further reduction to just the one monistic choice - as the other becomes the not-true.

This is @Banno's pattern of thought. You can always tell a reductionist by the way they build their conclusion into their terminology. Determinism is opposed to in-determinism. Sense is opposed to non-sense. By this kind of rhetorical trick, they hope to reinforce the notion that truth is something monistic. You either see things their way or you are simply opting for the option that their jargon already negates.

The sign of dialectical or triadic systems thinking is that the poles of any metaphysical dichotomy each have their own name. A dichotomy is where both choices are "true" in standing as the positive limit of the other. One doesn't negate the other. Each negates the other. And what do you get from a double negative? :grin:

So instead of determinate vs indeterminate, it becomes determinate vs vague. You don't signal that one choice is wrong by pointing out that it is merely an absence of some particular metaphysical quality. You give both their own proper name.

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

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.

So for example, vagueness is defined as that which is lacking all definiteness. And definiteness is that which is lacking all vagueness. But for each to have a measurable lack of the other, there must be that other to stand as a counterfactual possibility.

We are thus making statements about qualities being defined mutually "in the limit". A reciprocal relation.

Vagueness = 1/determinate. Determinate = 1/vagueness.

This is why a metaphysical dichotomy leads on to a triadic or holistic resolution - a Hegelian synthesis or Peircean semiotic. You have two things that exist as the third thing of their mutually co-dependent relation.

So when it comes to metaphysics as a historical practice, you can see how a division of thought might arise.

There are the reductionists who want to arrive at some monism and so they either proclaim the monisms of Idealism or Realism as "the one true path of all right thinking folk", or they get upset by paradoxes that arise and simply reject metaphysics as a discipline in its entirety.

The other path is the one that successful metaphysics has always taken since the ancient Greeks first developed the two general approaches to logical thought. And it is no surprise if logical holism might win the game. Nature is of course a cosmic whole. (Well, that is the general hypothesis that has worked out so far.)

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. — T Clark

Pragmatism is logical holism. So you can pick it for that reason.

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.

But if you want to do metaphysics, you have to study metaphysics for the actual logic it employs.

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. — T Clark

I don't see "metaphysics" as something beyond science. It clearly grounds science. And science then delivers a pragmatic judgement on the abductive speculations.

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.

So pragmatism rules. Otherwise it is just spinning tales that make no difference.

The reason why quantum physics keeps coming up is that it simply destroys "reductionist privilege" at root.

You can cobble together a decoherent "maths of reality" out of a combo of wave mechanics and statistical mechanics. You can arrive at an effective collapse of the wavefunction - with only a last tiny grain of uncertainty or vagueness. But in the end, there is no closure, no actual wavefunction collapse. Monism loses. The irreducible triadicity of a holistic systems logic has to be accepted.

So metaphysics provides two general cultural models of reality - the reductionist and the holistic. They are both just models - good for their various applications. One is great for seeing reality as a causal machine. A mereology of parts. The other jumps to the other pole in seeing reality as an organic whole. The Cosmos becomes something quite "other".

Ain't metaphysical, by definition. Physics is not metaphysics, otherwise what would be the point of having a separate subject area? — Wayfarer

This is just you boundary policing. Next you will be saying that Atomism played no part in the Scientific Revolution.

Interpretations of physics can be wildly different philosophically, yet both consistent with the observations. How is that 'physical'? And don't put words in my mouth. :rage:

Interpretations of physics can be wildly different philosophically, yet both consistent with the observations. — Wayfarer

Did you have an example in mind?

Of course. There's a book called The Metaphysics within Physics, Tim Maudlin. Another is Nature Loves to Hide, by Shimon Malin - he's more on the mystical end of the spectrum, but is a bona-fide physicist. Another is Physics and Philosophy, Bernard D'espagnat, ditto. There's Heisenberg's Physics and Philosophy, which is one of the canonical texts of the Copenhagen interpretation. Then there are those who insist that the 'Copenhagen interpretation' is radically incomplete and advocate the Everett formulation. See Sean Carroll, the most embarrasing graph in modern physics.

They're all quite different philosophically, but they're all working from the same set of observations. So the differences must be those of judgement and interpretation - metaphysical, in fact. The physics is effective and predictable but what it means is open to all of these different interpretations.

Interpretations of QM are interpretations of the physical, though. They say nothing about what may or may not underlie, or be beyond, the physical, as far as I can tell.

Interpretations of QM are interpretations of the physical, though. — Janus

Interpretations. That is the point. An observation of a physical phenomenon is just that - you register a measurement on an instrument, there's no room for disagreement about the reading. But what it means is wide open to interpretation.

True, but what it means is still (for physicists at least) in the physical context.

But that's just what is up for debate! that's the whole point! Some physicists insist that there are infininite parallel worlds, others insist that the observer creates what is observed. They're metaphysical disputes, absolutely no question about that. See The Mental Universe, Richard Conn Henry. He's a lecturing physicist who is arguing for Berkeleyian idealism, and he's not the only one. (I know - can of worms. I won't persist, with it but still...)

Nice graph. I noted that the information-based/information theoretical option scored only 24%.

I think it's a question of values. — T Clark

I don't see how.

I'm not saying that metaphysical interpretations are not possible, but they are not inevitable and nor are they, as far as I am aware, mainstream in the physics community. If there were infinite parallel worlds, those worlds would be physical, and if it is down to the "observer effect", the observer does not have to be understood to be in any way non-physical. As to the latter, if I understand correctly, it's also the case that the 'decoherence' interpretation employs a much broader notion of observer than would tally with the common notion (i.e. the term 'observer' is not confined to humans, higher animals, or even to animals).

I'm not saying that metaphysical interpretations are not possible, but they are not inevitable and, as far as I am aware, mainstream in the physics community. — Janus

That's because most physicists are not employed to speculate.

As to the latter, if I understand correctly, it's also the case that the 'decoherence' interpretation... — Janus

It's a devilishly difficult thing to understand, but as I understand it, it doesn't make 'the observer problem' go away.

They're all quite different philosophically, but they're all working from the same set of observations. — Wayfarer

Sigh. How is your case furthered by citing all these physicists taking different metaphysical positions?

They say nothing about what may or may not underlie, or be beyond, the physical, as far as I can tell. — Janus

They certainly ought to constrain what would be considered credible.

Like after Darwin, you might quarrel about how humans arose from apes. But no longer do you need to worry about the mechanics of turning ribs into first wombs.

Interpretations. That is the point. An observation of a physical phenomenon is just that - you register a measurement on an instrument, there's no room for disagreement about the reading. But what it means is wide open to interpretation. — Wayfarer

It is one thing when the needle moves. It is another thing when a guy in a white coat told you it was going to move exactly like that for exactly this reason.

The situation is no longer “wide open” for interpretation. You have a job to do to say why some other interpretation would both predict the same thing and much more besides.

How is your case furthered by citing all these physicists taking different metaphysical positions? — apokrisis

Well if you don’t understand the point there’s not a lot of use trying to explain it again.

With regards to the reading of the dial - there is a philosophical position called ‘instrumentalism’ but not everyone holds it. And the reasons that not everyone holds it can’t be found within physics.

Well if you don’t understand the point there’s not a lot of use trying to explain it again. — Wayfarer

Physics is not metaphysics, otherwise what would be the point of having a separate subject area? — Wayfarer

Did you understand your own point. Seems not.

Trying again.

Physics practices its own winning brand of metaphysical world-modelling. It gets on with what it believes works. — apokrisis

Its models are mathematical formulations that are tested against observational data, but that is not an exercise in metaphysics. The disputes about the interpretation of quantum mechanics can be regarded as metaphysical but the practice of physics is not as it can be carried out without reference to any such interpretations.

it’s not about different interpretations of the same facts. It is about the axiomatic basis by which some observation could constitute “a fact”.

So the metaphysical work gets done to set up the theory. It doesn’t follow the measurements as they already build in some metaphysical basis.

do you think the Bohr-Einstein debates were about physics or metaphysics?