The Short Case for Verificationism

post by ike · 2020-09-11T18:48:00.372Z · score: 4 (2 votes) · LW · GW · 43 comments

Follow-up to: https://www.lesswrong.com/posts/PSichw8wqmbood6fj/this-territory-does-not-exist [LW · GW]

Here's a simple and direct argument for my version of verificationism.

Note that the argument uses ontological terms that are meaningless on my views. It functions as a reductio - either one must accept the conclusion, or accept that some of the premises are meaningless, which amounts to the same thing.

Premise 1: The level IV multiverse is possible.

Premise 2: If the level IV multiverse is possible, then we cannot know that we are not in it.

Lemma 1: We cannot know that we are not in the level IV multiverse.

Premise 3: If we are in the level IV multiverse, then ontological claims about our world are meaningless, because we simultaneously exist in worlds where they are true and worlds where they are not true.

Lemma 2: If we can know that ontological claims are meaningful, then we can know we're not in the level IV multiverse.

Conclusion: We cannot know that ontological claims about our world are meaningful.

Edited to add two lemmas. Premises and conclusion unchanged.

43 comments

Comments sorted by top scores.

comment by G Gordon Worley III (gworley) · 2020-09-11T21:55:45.208Z · score: 5 (2 votes) · LW(p) · GW(p)

It might help if you could be more specific on what it means for a statement to be "meaningless". Simply unable to treat it as a fact?

comment by ike · 2020-09-11T22:08:43.200Z · score: 2 (2 votes) · LW(p) · GW(p)

I think a claim is meaningful if it's possible to be true and possible to be false. Of course this puts a lot of work on "possible".

comment by G Gordon Worley III (gworley) · 2020-09-11T23:47:27.323Z · score: 2 (1 votes) · LW(p) · GW(p)

So, I think the crux of why I don't really agree with your general gist and why I'm guessing a lot of people don't, is we see meaningfulness as something bigger than just whether or not something is a fact (statement that has a coherent truth value). To most I think, something is meaningful if it somehow is grounded in external reality, not whether or not it can be assess to be true, and many things are meaningful to people that we can't assess the truthiness of. You seem to already agree that there are many things of which we cannot speak of facts, yet these non-facts are not meaningless to people. Just for example, you perhaps can't speak to whether or not it is true that a person loves their mother, but that love is likely quite meaningful to them. There's a kind of deflation of what you mean by "meaning" here that, to me, makes this position kind of boring and useless, since most of the interesting stuff we need to deal with is now outside the realm of facts and "meaning" by your model.

comment by ike · 2020-09-11T23:54:47.777Z · score: 1 (1 votes) · LW(p) · GW(p)

> To most I think, something is meaningful if it somehow is grounded in external reality

This is of course circular when trying to justify the meaningfulness of this "external reality" concept.

>we can't assess the truthiness of

This is one way to state verificationism, but I'm not *assuming* this, I'm arguing for it.

>Just for example, you perhaps can't speak to whether or not it is true that a person loves their mother, but that love is likely quite meaningful to them.

It might be meaningless to me, and meaningful for them.

>most of the interesting stuff we need to deal with is now outside the realm of facts and "meaning" by your model.

What interesting stuff do we need to deal with that don't affect our decisions or probability distributions over our experiences? Since my model doesn't affect either of those, by construction. (It does hint at some utility functions being somewhat incoherent, but I'm not necessarily standing by that, I prefer to let utility function range broadly.)

comment by TAG · 2020-09-12T15:09:19.209Z · score: 1 (1 votes) · LW(p) · GW(p)

I think a claim is meaningful if it’s possible to be true and possible to be false. Of course this puts a lot of work on “possible”.

That's not the standard verificationist claim, which is more that things are meaningful if they can be verified as true or false.

comment by ike · 2020-09-12T15:19:55.352Z · score: 1 (1 votes) · LW(p) · GW(p)

No, it would be circular if I defined meaning to already include the verificationist claim.

Rather, I define meaning in other terms and then argue that this implies the verificationist claim.

comment by TAG · 2020-09-12T15:29:21.829Z · score: 1 (1 votes) · LW(p) · GW(p)

There are gaps in the argument, then.

comment by ike · 2020-09-12T15:48:43.658Z · score: 1 (1 votes) · LW(p) · GW(p)

My premises imply the conclusion. You might not like some of the premises, perhaps.

comment by TAG · 2020-09-12T17:52:16.667Z · score: 1 (1 votes) · LW(p) · GW(p)

I don't think they do. But that should not be in dispute. The point of a logical argument is to achieve complete clarity about the premises and the way they imply the conclusion.

comment by ike · 2020-09-12T18:08:02.482Z · score: 1 (1 votes) · LW(p) · GW(p)

I added two lemmas to clarify. I guess you could quibble with lemma 2, I think it does follow if we assume that we know or at least can know premise 3, but that seems plausible if you're willing to accept it as a premise at all.

comment by ike · 2020-09-12T18:01:05.340Z · score: 1 (1 votes) · LW(p) · GW(p)

I could break it up into more steps if it's not entirely clear that the premises imply the conclusion.

comment by Benjy Forstadt (benjy-forstadt-1) · 2020-09-11T22:23:57.618Z · score: 1 (1 votes) · LW(p) · GW(p)

I think for your purposes you can just define meaningless as “neither true nor false” without detouring into possibility

comment by ike · 2020-09-11T22:34:37.059Z · score: 1 (1 votes) · LW(p) · GW(p)

For this argument, yes, but it might not be sufficient when extending it beyond just uncertainty in verificationism.

comment by Benjy Forstadt (benjy-forstadt-1) · 2020-09-11T20:36:26.020Z · score: 4 (3 votes) · LW(p) · GW(p)

This looks like an argument, not for verificationism, but for the impossibility of knowing that verificationism is false. This seems unproblematic to me.

I am also skeptical of premise 3. It relies on a certain conception of personal identity in Level IV - that in some sense we are all our copies in the multiverse, so they count as a single observer

comment by ike · 2020-09-11T21:05:18.890Z · score: 1 (1 votes) · LW(p) · GW(p)

At the very least, it should make verificationism more plausible to people who consider the level IV multiverse plausible.

I think the argument might go through in a weaker form with lower levels. But I suspect many people are already verificationist in that weaker form, to some extent. E.g. if you subscribe to "the electron is not in state A or state B until we measure it", then you're committed to a mild form of verificationism corresponding to the level III multiverse.

Compare to my argument - the ontological statements it applies to are just those statements that are both true and false on different parts of the multiverse containing us. I think this directly corresponds, in the case of the quantum multiverse, to what many people would consider things that lack a fact of the matter either way.

comment by Benjy Forstadt (benjy-forstadt-1) · 2020-09-11T21:47:48.239Z · score: 1 (1 votes) · LW(p) · GW(p)

I think I agree it makes verificationism a bit more plausible if you already find Tegmark IV plausible.

Regarding the quantum multiverse - yes, I agree, that is the usual way of thinking about things, moreover the usual thinking is that most ordinary statements about the future are similarly indeterminate. On the other hand, this isn’t the usual thinking about the cosmological multiverse. In a quantum multiverse, universes literally branch, in a cosmological multiverse, universes merely diverge. So, assuming the usual views about these multiverses are correct, would Level IV be like the quantum multiverse or would it be like the cosmological multiverse?

I can see both ways, but on reflection, it seems more natural to say it’s like the quantum multiverse. On the cosmological picture, for every consistent mathematical structure, you’ve got a separate self contained world, and there can be a lot of duplicate structure across worlds, but there can’t be duplicate worlds. It seems to make a weird distinction between worlds and the substructures in worlds. On the quantum picture, you can think of the observer as a mathematical structure in its own right, that is instantiated in many different larger structures, and there’s no fundamental notion of “world”.

So fine, this gives you something like verificationism.

comment by ike · 2020-09-11T22:10:14.875Z · score: 1 (1 votes) · LW(p) · GW(p)

I'm not sure what you mean by cosmological multiverse.

Re distinction between branching and diverging - I think even without adopting verificationism, one can plausibly argue that that distinction is meaningless.

comment by Benjy Forstadt (benjy-forstadt-1) · 2020-09-11T22:21:13.890Z · score: 1 (1 votes) · LW(p) · GW(p)

By cosmological multiverse, I mean Level I or II. It is arguable that the distinction between branching and diverging is meaningless, or that Level I and II should be viewed as branching, but that is not the usual view.

I think it’s clear it’s not meaningless, and that those who think it’s meaningless just favor viewing every kind of splitting as branching. Let me explain: To say the future branches, what I mean is that there is no fact of the matter what exactly will happen in the future. To say the future diverges, what I mean, is that there is a fact of the matter about what will happen in the future, but that there are observers just like me who will observe a different future.

Either there is a fact of the matter what will happen in the future, or there isn’t (?!). It may indeed be the case that the concept of diverging is incoherent, in which case the only kind of splitting is branching. This is a heterodox view, however.

comment by ike · 2020-09-11T22:24:21.854Z · score: 1 (1 votes) · LW(p) · GW(p)

So your claim that it's not meaningless is basically just the negation of my third premise.

comment by Benjy Forstadt (benjy-forstadt-1) · 2020-09-11T22:38:19.142Z · score: 1 (1 votes) · LW(p) · GW(p)

I’m getting a bit lost, so forgive me if I’m repeating myself.

I’m uncertain about the truth of premise 3, because I’m uncertain whether Tegmark Level IV implies the existence of nonidentical duplicates. I compared Level IV to two theories, one of which is commonly thought to imply the existence of nonidentical duplicates, and the other which is not commonly thought to.

I prefer to define “branching” in a way that is compatible with views under which the concept of “nonidentical duplicate” is inconsistent or meaningless.

comment by TAG · 2020-09-12T15:04:51.502Z · score: 2 (2 votes) · LW(p) · GW(p)

If we are in the level IV multiverse, then ontological claims about our world are meaningless, because we simultaneously exist in worlds where they are true and worlds where they are not true

There are a number of different claims jammed together, there.

Firstly, its not clear whether a level IV multiverse means there are multiple copies of you with identical brain states but living in different environments -- why would you be in a "seeing a tree" brain state if you are on a planet with no trees? It's also not clear whether you can have qualitatively identical counterparts that don't share brain states -- what then makes them identical? It's also not clear that qualitative identity is sufficient for numerical identity. Basically, multiversal theories don't supply a theory of personal identity -- that has to be an additional assumption.

(Oddly enough, there is a better way of getting to the same point. If we can't prove that we are not living in a simulation, then we can't resolve basic ontological questions, even if we have excellent predictive theories).

Secondly, even if ontological questions can't be answered , that doesn't mean they are meaningless, under the one and only definition of "meaning" anyone ever had.

So, I think the crux of why I don’t really agree with your general gist and why I’m guessing a lot of people don’t, is we see meaningfulness as something bigger than just whether or not something is a fact (statement that has a coherent truth value).

Indeed!

comment by ike · 2020-09-12T15:29:34.629Z · score: 1 (1 votes) · LW(p) · GW(p)

Firstly, its not clear whether a level IV multiverse means there are multiple copies of you with identical brain states but living in different environments -- why would you be in a "seeing a tree" brain state if you are on a planet with no trees?

It's very clear, to the contrary. A universe with an identical brain state but without any trees absolutely is part of it, there is a mathematical structure corresponding to the brain state that doesn't also contain trees.

what then makes them identical

My standard criteria is subjective indistinguishability. Any universe that we can't tell that we're not in contains a copy of us.

Re simulation: level IV contains a broad range of theories even weirder than simulations of us, infinitely many of which make ontological claims come out alternatively true or false. We certainly can't prove any ontological claim.

Secondly, even if ontological questions can't be answered , that doesn't mean they are meaningless, under the one and only definition of "meaning" anyone ever had.

We'd at least have to significantly complicate the definition. I think people generally intend and expect ontological claims to have a coherent truth value, and if that's not the case then there's no referent for what people use ontological claims for. If you don't want to call it meaningless, fine, but it's certainly weird.

comment by TAG · 2020-09-12T18:13:59.175Z · score: 1 (1 votes) · LW(p) · GW(p)

You are making two claims..about whether ontological indeterminacy holds, and about the meaning of "meaning" .

Setting aside the second claim , the first claim rests on an assumption that the only way to judge a theory is direct empiricism. But realists tend to have other theoretical desiderata in mind..a lot would reject simulations and large universes on the basis of Occams Razor, for instance.

As for the rest..you might have a valid argument that it's inconsistent to believe in both empirical realism and large universes.

comment by ike · 2020-09-12T18:18:26.347Z · score: 2 (2 votes) · LW(p) · GW(p)

I accept Occam, but for me it's just a way of setting priors in a model using to make predictions.

And part of my argument here is how the mere possibility of large universes destroys the coherency of realism. Even those rejecting simulations would still say it's possible.

(Putnam would say it's meaningless, and I would in fact agree but for different reasons.)

comment by TAG · 2020-09-12T19:21:13.964Z · score: 1 (1 votes) · LW(p) · GW(p)

I accept Occam, but for me it’s just a way of setting priors in a model using to make predictions.

But you don't have a proof that that is the only legitimate use of Occam. If realists can use Occam to rescue realism, then realism gets rescued.

And part of my argument here is how the mere possibility of large universes destroys the coherency of realism. Even those rejecting simulations would still say it’s possible.

That would be the sort of problem that probablistic reasoning addresses.

comment by ike · 2020-09-12T19:33:59.898Z · score: 1 (1 votes) · LW(p) · GW(p)

>But you don't have a proof that that is the only legitimate use of Occam. If realists can use Occam to rescue realism, then realism gets rescued.

Surely the burden of proof is on someone suggesting that Occam somehow rescues realism.

Besides, level IV is arguably simpler than almost any alternative, including a singleton universe.

comment by TAG · 2020-09-12T19:42:08.182Z · score: 1 (1 votes) · LW(p) · GW(p)

Surely the burden of proof is on someone suggesting that Occam somehow rescues realism

That's not sure at all. Anti realism is quite contentious.

Besides, level IV is arguably simpler than almost any alternative, including a singleton universe.

It can come out as very simple or very complex depending on how you construe Occam.

comment by ike · 2020-09-12T19:57:54.021Z · score: 1 (1 votes) · LW(p) · GW(p)

Anti realism is quite contentious.

That doesn't mean that Occam grounding realism is at all plausible. I've laid out an argument for verificationism here and met my burden of proof. Suggesting that there might possibly be a counterargument isn't meeting the opposing burden of proof.

comment by TAG · 2020-09-12T20:42:25.369Z · score: 1 (1 votes) · LW(p) · GW(p)

Meeting contrary arguments is part of a making an argument. There definitely is such a counterargument, even if you have never heard of it. That's what steel manning and strong manning are all about.

comment by ike · 2020-09-12T21:09:10.548Z · score: 1 (1 votes) · LW(p) · GW(p)

I don't know what a plausible version of the argument you're hinting at would look like. If you think there's such a plausible argument, please point me at it.

comment by TAG · 2020-09-14T18:25:52.899Z · score: 1 (1 votes) · LW(p) · GW(p)

I don't know what your thoughts on plausibility are. But multiversal theories are straightforwardly excluded by the original version of Occams Razor, the one about not multiplying entities.

comment by ike · 2020-09-14T21:41:30.078Z · score: 1 (1 votes) · LW(p) · GW(p)

To the extent Occam is interpreted as saying that more complicated theories are impossible, as opposed to unlikely, it's not plausible.

As above, my claim rests only on the possibility of a multiverse.

comment by TAG · 2020-09-15T11:07:04.412Z · score: 1 (1 votes) · LW(p) · GW(p)

Why should something that is possible but low probability have so much impact?

comment by ike · 2020-09-15T13:19:14.243Z · score: 1 (1 votes) · LW(p) · GW(p)

The argument is laid out in OP.

comment by TAG · 2020-09-17T18:14:01.549Z · score: 1 (1 votes) · LW(p) · GW(p)

I don't see any mention of probability.

comment by ike · 2020-09-17T18:52:41.512Z · score: 1 (1 votes) · LW(p) · GW(p)

The argument does not depend on probability.

If you disagree with the conclusion, please explain which premise is wrong, or explain how the conclusion can be false despite all premises holding.

comment by TAG · 2020-09-17T19:32:34.685Z · score: 1 (1 votes) · LW(p) · GW(p)

Since the argument does not mention probability, it doesn't refute the counterargument that unlikely scenarios involving simulations or multiple universes don't significantly undermine the ability to make claims about ontology.

comment by ike · 2020-09-17T22:04:29.653Z · score: 1 (1 votes) · LW(p) · GW(p)

That's not a counterargument, as it's fully consistent with the conclusion.

comment by TAG · 2020-09-18T10:04:18.088Z · score: 1 (1 votes) · LW(p) · GW(p)

don’t significantly undermine the ability to make claims about ontology.

comment by ike · 2020-09-18T15:00:44.003Z · score: 1 (1 votes) · LW(p) · GW(p)

If you take that as a premise and you consider it contradictory to my conclusion and you accept my premises, then the premises you accept imply a contradiction. That's your problem, not mine.

comment by TAG · 2020-09-21T17:49:35.744Z · score: 1 (1 votes) · LW(p) · GW(p)

Read back,there's an even number of negatives.

comment by ike · 2020-09-21T19:55:47.943Z · score: 1 (1 votes) · LW(p) · GW(p)

Not following. Can you state your point plainly? Which part of my argument do you reject?

comment by Cookie Factory (cookie-factory) · 2020-09-12T17:16:18.719Z · score: -6 (3 votes) · LW(p) · GW(p)

Like flowers in the spring and leaves in the fall, the decline phase within the civilization cycle brings out all the flavor du jour takes on solipsism and nihilism from the nerd demographic. The more things change the more they stay the same.