It looks like you're pretty firmly wedded to the idea of a Cartesian theatre. — frank

No, actually I'm not, I think it's a very simplistic representation of dualist principles. I just hear people asserting that this representation has been disproven (when to my knowledge it hasn't), and I want to know if I've missed something, or if someone has come up with something new. But all you had was the false representation of infinite regress, which I've seen before.

I'm not, but it does occasionally jar me to know that I'm a product of chemicals and customs. :grimace: — frank

If it jars you then why believe it? When something is so highly counter-intuitive, then you ought not believe it unless it is well proven. That it's pop-culture obviously does not imply that it's been proven.

We know that a rigid designator picks out the very same individual every possible world. — Banno

There is no such thing as the same individual in different possible worlds. That's a bad fiction which allows that the same individual has contradicting properties in different possible worlds, which implies that they cannot be the same individual. In other words, violation of the law of non-contradiction occurs if you call them "the same individual". Therefore "the individual" must be proper to one possible world only, and any other possible world would have a different individual. Never the twain shall meet. Frank's got the right idea, you are lost.

I'm surprised you remember. — frank

From your insistence that I "read the article", it seems you didn't until reminded.

https://thephilosophyforum.com/discussion/4545/naming-and-necessity-reading-group/p1

https://thephilosophyforum.com/discussion/4857/naming-and-necessity-lecture-three/p1

The second link has the discussion of Lecture Three, and so of kinds.

Yeah, you won't like it. He shows that there are a posteriori necessities.

There is no such thing as the same individual in different possible world — Metaphysician Undercover

:roll:

That was pre-pandemic. I'm not the same person I was then.

Saw what you did there.

Face it Banno, you're wrong. An individual cannot exist in numerous possible worlds. If the designator picks out something which is common to numerous possible worlds, it is clearly not an individual.

@frank, what's you reply to 's

An individual cannot exist in numerous possible worlds. — Metaphysician Undercover

?

Banno is operating on a very false idea of what an "individual" is. A name which picks out an individual designates an object in the world. If we represent possibilities for describing that individual (possible predications), each possible world is a different representation, therefore each would signify a different individual. If some of the representations have something in common, this does not mean that they represent the same individual. To represent the same individual would require that the representations (possible worlds) have everything in common.

If there was a single feature of the designated individual which was common to all possible worlds, we would say that this is a necessary, or essential feature of the individual. We could not entertain the possibility of a representation of the individual without including that feature.

Kripke brought up possible worlds as an aid to understanding how modality works. There are ways of parsing modal expressions that turn them into nonsense, and I think MU would be inclined to do that. He'd say we can't assert that Nixon could have lost, because if he lost, that wouldn't be Nixon.

I think this confusion arises from trying to do something ontological with modal expressions, when that's not the intent behind them. We're generally just playing with logical or metaphysical possibility, and that's the way possible worlds should be taken: as logical hypotheses.

He shows that there are a posteriori necessities. — Banno

For instance? Quick and easy and to the point, please.

Ok, good answer. So no going to counterpart theory or stuff like that. Yep, as usual, Meta is muddled.

So we might be able to work out where exactly we differ in our readings of Kripke.

Individuals need not have an essence.
— Banno

According to Kripke, they always do. — frank

According to Kripke, kinds have an essence, but not individuals.

Now an essence is here understood as a property that belongs to the item in every possible world. So there need be no property of Mww that belongs to him in every possible world, but the property of being made from H₂O is true of water in every possible world. It's being made of H₂O is essential to water.

Agree?

...the property of being made from H₂O is true of water in every possible world, but is known a posteriori.

An individual cannot exist in numerous possible worlds. If the designator picks out something which is common to numerous possible worlds, it is clearly not an individual. — Metaphysician Undercover

I think you're missing the point/meaning of possible-world semantics, MU. Aside from people like Lewis (who is a realist wrt possible worlds), "existing in a possible world" is (essentially) just a different way of saying that something isn't contradictory, that it does not entail a contradiction. That's it. So saying an individual exists in a possible world is only to say that some particular description, predicate, or state of affairs involving that individual is logically possible- it doesn't involve any contradiction or inconsistency.

So yes, an individual "exists" in numerous, maybe even uncountable, possible worlds, because there are numerous, maybe even uncountable, logically-possible propositions, predicates, etc that we can say of a given individual.

I doubt Meta is talking about counterpart theory. He'll be flying on a cloud of his own making.

Yeah it occurred to me that engaging with MU on matters involving AP/philosophy of language/modal logic/etc might not be the brightest idea I've ever had, but I've been out of the mix for so long I think my tolerance for philosophical shenanigans is fairly high at the moment (something I expect will change/fade rather quickly).

Fair enough. It's your time... I've long since given up.

It's being made of H₂O is essential to water. — Banno

This is a notion that still mystifies me.

According Kripke, his wooden lectern is made of wood in every possible world where that lectern exists. There are all sorts of properties we could change and still have the same lectern, but being wooden isn't one of them.

It's an essential property. Do you disagree with him about this?

Kripke brought up possible worlds as an aid to understanding how modality works. There are ways of parsing modal expressions that turn them into nonsense, and I think MU would be inclined to do that. He'd say we can't assert that Nixon could have lost, because if he lost, that wouldn't be Nixon.

I think this confusion arises from trying to do something ontological with modal expressions, when that's not the intent behind them. We're generally just playing with logical or metaphysical possibility, and that's the way possible worlds should be taken: as logical hypotheses. — frank

Yes, that's exactly the point, "an individual" speaks of something in a completely different ontological category from what a "logical hypothesis" speaks of. So Banno's attempt to bring the individual into the logical hypothesis was a category mistake.

We see this same mistake quite often when people speak of "possible worlds". They will say for instance, that one of the possible worlds is the actual world. But the possible worlds are just representations, logical hypotheses, and although one of the possible worlds might be judged as the correct representation, or some feature might be common to a whole set of possible worlds, it is still not the actual world, as this is a distinct category from the representation.

So yes, an individual "exists" in numerous, maybe even uncountable, possible worlds, because there are numerous, maybe even uncountable, logically-possible propositions, predicates, etc that we can say of a given individual. — busycuttingcrap

No, that's the category mistake described above. An individual does not exist in any possible worlds. As frank explained, possible worlds are logical hypotheses. Individuals are actual objects in the physical world. There might be individuals represented by such hypotheses, but no individuals exist in these hypotheses

An individual cannot exist in numerous possible worlds. — Metaphysician Undercover

Agreed. If he exists at all, in whichever of the possible worlds he exists in, that world must be necessary.

Carry on with your terribly misguided philosophy (if one can call it that) then.

According Kripke, his wooden lectern is made of wood in every possible world where that lectern exists. There are all sorts of properties we could change and still have the same lectern, but being wooden isn't one of them.

It's an essential property. Do you disagree with him about this? — frank

Trying to get through to Banno is like banging your head on a brick wall. Banno's been trying to argue that the essential property (what's common to every possible world), is the individual.

Oh, yes. But the lectern is identified via it's description - being wood - so in effect he is saying "the wooden lectern is necessarily made of wood".

The example is found in the article Identity and necessity, not Naming and Necessity. Bottom of p.178. (the link is a dreadful PDF - anyone have a better copy?).

Here's an example for those of you having difficulty understanding. In possible world #1, X is red. In possible world #2, X is not red. Clearly it cannot be the case that "X" refers to the same individual, unequivocally, unconditionally, or in any unqualified way, or else there would be contradiction, in saying that X is both red and not red.

So we have two principal choices, either "X" refers to a different individual in possible world #1, from what it refers to in possible world #2, or else it is just like a placeholder within those possible worlds, as a representation of a single individual which is supposed to exist in a separate world all together. The latter is the conventional interpretation. The contradicting propositions are statements of possibility for an individual believed to exist in a separate actual world. But this means that "X" refers neither to an individual in possible world #1, nor to an individual in possible world #2, but to an individual in some separate world. In those 2 possible worlds, "X" just provides a means for us to talk about possibilities for that individual which exists in a completely separate world.

It appears like the existence of the Many Worlds interpretation of quantum mechanics, has produced an acceptance of the other principal interpretation. When the numerous different possible worlds are each assumed to have actual existence, as in MWI, then X must refer to a different individual in each possible world. Being a part of a different world in each case would render the individuals as different individuals. If X is taken to refer to the same individual existing in many different worlds at the same time, incoherency results from the contradiction of saying that numerous different things (different by way of each having a different description) are actually one and the same thing.

Oh, yes. But the lectern is identified via it's description - being wood - so in effect he is saying "the wooden lectern is necessarily made of wood".

The example is found in the article Identity and necessity, not Naming and Necessity. Bottom of p.178. (the link is a dreadful PDF - anyone have a better copy?). — Banno

Oh. Thanks for the correction.

But the lectern is identified via it's description - being wood - so in effect he is saying "the wooden lectern is necessarily made of wood". — Banno

Where do lecterns exist ?

Kripke gives the example of "here is a lectern" as a description of something made of wood, something that can only be known a posteriori and is an essential property.

However, what happens when we move from the demonstrative pronoun to the definite article.

There is no single property that lecterns have. Some are made of wood, some of metal, some have a flat base, some a legged base, some are grey in colour, some brown, etc. But as Wittgenstein pointed out, objects such as lecterns do have a family resemblance, such that a human observer can judge the difference between a lectern and a non-lectern.

As lecterns have no essential property, then lectern is more like a rigid designator than a description, as Mary as a name is a rigid designator, having no properties.

If lecterns exist only as a family resemblance between "this lectern" and "that lectern", and family resemblances is a human judgement, how can lecterns exist in the world, unless family resemblance is also something that exists in the world ?

↪Mww ...the property of being made from H₂O is true of water in every possible world, but is known a posteriori. — Banno

Known a posteriori in this world. Empirical knowledge obtained in a given world cannot translate to empirical knowledge in some possible world without contradicting the conditions for empirical knowledge. Ever been to a possible world, observed what is already cognized as water, analyzed it to find H2O in it, or not? Unless that happens, knowledge by experience is utterly irrelevant.

So it must be that is hardly an a posteriori necessity. Only if a myriad of presuppositions hold, the very epitome of contingent identity, would water on any possible world perfectly replicate water as it is known a posteriori on this one, the presuppositions we have logical….you know, one of those cursed a priori “scripts”…… but no empirical, justifications whatsoever, to hold.

So, yeah, true enough, water is made from H2O in any possible world, iff every single antecedent condition by which that criteria is met here, is met as well there. THAT……is what we have no warrant to authorize, insofar as the plethora of antecedent conditions makes explicit there are some of which we have no knowledge, which means we could never claim the criteria there is met because we don’t even know the totality of the criteria here. Therefore, a posteriori necessity is, while not absolutely false, is not necessarily true.

Philosophy was warned about this misuse of reason, but apparently, chose to disregard it.

Yes, that's exactly the point, "an individual" speaks of something in a completely different ontological category from what a "logical hypothesis" speaks of. So Banno's attempt to bring the individual into the logical hypothesis was a category mistake.

We see this same mistake quite often when people speak of "possible worlds". They will say for instance, that one of the possible worlds is the actual world. But the possible worlds are just representations, logical hypotheses, and although one of the possible worlds might be judged as the correct representation, or some feature might be common to a whole set of possible worlds, it is still not the actual world, as this is a distinct category from the representation. — Metaphysician Undercover

It seems like you didn't hear me the first time. Every time you read "there is/exists a possible world such that X, Y, or Z", mentally substitute "it is not contradictory/inconsistent that X, Y, or Z". Possible-world semantics isn't actually making an ontological claim (at least, not if you're not David Lewis), its making a claim about logical consistency. And so obviously, the actual world is a possible world, since "being a possible worlds" means "not being contradictory/logically inconsistent". And the actual world is not self-contradictory or logically inconsistent, so, it is a possible world. I mean, obviously, how could the actual world be actual, if it wasn't possible?

No, that's the category mistake described above. An individual does not exist in any possible worlds.

Sure it does, because "existing in a possible world" isn't an existence claim about other worlds, despite appearances to the contrary. Replace "existing in a possible world" with "being logically possible/self-consistent", and your objection disappears.

You're just misunderstanding what possible world semantics means, for which you don't deserve blame: it can be highly misleading to say that "there exists a possible world" when all you mean is that something is logically possible or self-consistent. But it is a useful way to conceptualize possibility and modality, in certain contexts. Its far from the weirdest thing philosophers are prone to talk about.

Carry on with your terribly misguided philosophy (if one can call it that) then. — Metaphysician Undercover

Understanding how certain technical terms are actually used in the relevant sub-field is actually just about the opposite of misguided philosophy: its trying to understand what philosophers mean, on their own terms. So its sort of necessary for a proper understanding of any philosopher. But I was admittedly tentative about engaging with you on this, because you are, frankly, sort of known for being stubborn about these things and not amenable to correction. But I assure you, as someone who spent most of their undergrad philosophy degree focusing on contemporary analytic philosophy and philosophy of language (so, for instance, folks like Saul Kripke), you're simply misunderstanding what these terms usually mean, in the context of contemporary philosophy/modal logic.

, : Modal reasoning is fraught with misunderstanding. Every thread on the topic here has been hindered by the sort of misunderstandings expressed by and . In Meta's case the misunderstanding is I think quite wilful. I would not expect any progress there. Some of the stuff found in modal logic runs contrary to Kant, so will be anathema to Mww, so although Mww is amenable to reason, it will be an uphill battle to explain more recent developments.

I'm sure you are both aware of this. It's a shame, since there are interesting problems in modal reasoning that we might discuss, but any discussion on these forums is plagued by such background noise from 'modal sceptics". I do not expect to achieve any depth.

This ties in with the recent discussion of forum quality, and I'd suggest following 's suggestion there of restricting the discussion to a particular essay. That way at the least it will be easier for mods to identify and deal with off-topic, dissimulating or obstructive comments.

I'm also aware that the link between this discussion of modality and the OP is not obvious.

Perhaps a thread on Identity and necessity?

However, what happens when we move from the demonstrative pronoun to the definite article. — RussellA

Good question. In modal logic it is important to be clear about different ways in which individuals, kinds and descriptions are treated. So a lectern which is picked out by a description will be treated differently to say an individual picked out by a proper name.

I'd say the wooden lectern (definite article) is necessarily made of wood - if it were not, it would be some other lectern. But perhaps that lectern (demonstrative pronoun) might have been made of ice.

Subtle stuff, prone to induce long tedious threads.

Perhaps a thread on Identity and necessity? — Banno

Sounds fun!

It seems like you didn't hear me the first time. Every time you read "there is/exists a possible world such that X, Y, or Z", mentally substitute "it is not contradictory/inconsistent that X, Y, or Z". Possible-world semantics isn't actually making an ontological claim (at least, not if you're not David Lewis), its making a claim about logical consistency. And so obviously, the actual world is a possible world, since "being a possible worlds" means "not being contradictory/logically inconsistent". And the actual world is not self-contradictory or logically inconsistent, so, it is a possible world. I mean, obviously, how could the actual world be actual, if it wasn't possible? — busycuttingcrap

OK, I understand what you are saying here. Now the problem is that when someone like Banno says that X,Y, or Z refers to "an individual" this is an ontological claim. So you can have your X, Y, and Z referring to nothing if you like, or even refer to a type, and claim logical consistency, but as soon as you say that one of these refers to an individual then you need to account for the existence of that individual because you have made an ontological claim.

Sure it does, because "existing in a possible world" isn't an existence claim about other worlds, despite appearances to the contrary. Replace "existing in a possible world" with "being logically possible/self-consistent", and your objection disappears. — busycuttingcrap

This does not solve the problem, because Banno's claim was that the designated individual exists in numerous possible worlds. And this produces logical inconsistency because the description of the designated individual is different in the different logical possibilities. Therefore these cannot be the same individual in distinct logical possibilities because of that inconsistency. Each logical possibility must necessarily represent a distinct individual.

So for instance, it is possible that MU is male, and it is possible that MU is female. In these two logical possibilities (these two possible worlds), "MU" does not refer to the same individual. In one possible world the individual is male and in the other possible world the individual is female. Therefore if the claim is that MU refers to an individual within each of those possibilities, these are necessarily two distinct individuals, on male, one female.

Understanding how certain technical terms are actually used in the relevant sub-field is actually just about the opposite of misguided philosophy: its trying to understand what philosophers mean, on their own terms. So its sort of necessary for a proper understanding of any philosopher. But I was admittedly tentative about engaging with you on this, because you are, frankly, sort of known for being stubborn about these things and not amenable to correction. But I assure you, as someone who spent most of their undergrad philosophy degree focusing on contemporary analytic philosophy and philosophy of language (so, for instance, folks like Saul Kripke), you're simply misunderstanding what these terms usually mean, in the context of contemporary philosophy/modal logic. — busycuttingcrap

Great, now are you ready to address the issue, which is the existence of the individual, in relation to logical possibilities, because you seem to have completely skirted the issue in this post.

OK, I understand what you are saying here. Now the problem is that when someone like Banno says that X,Y, or Z refers to "an individual" this is an ontological claim. So you can have your X, Y, and Z referring to nothing if you like, or even refer to a type, and claim logical consistency, but as soon as you say that one of these refers to an individual then you need to account for the existence of that individual because you have made an ontological claim. — Metaphysician Undercover

The claims in question aren't ontological claims; that's the entire point. They sound or look like ontological claims, but they are not. So when I say that "there is a possible world such that X", for instance if I say "there is a possible world such that MU is president of the United States of America", I am not making an ontological claim, I am not asserting the existence of anything: the phrase "there is a possible world such that X" is synonymous and interchangeable with the phrase "X is logically possible/self-consistent/non-contradictory". So I'm not asserting that there exists any such world, I'm just saying that the proposition of MU being the president of the USA is logically possible/does not entail a contradiction.

This does not solve the problem, because Banno's claim was that the designated individual exists in numerous possible worlds. — Metaphysician Undercover

Sure it does: "existing in a possible world" means not entailing a contradiction. And there are numerous claims we can make about a given individual that do not entail contradictions (remember, "there exists a possible world" is synonymous with "does not entail a contradiction").

And so this suffices to address your concern about "the existence of the individual": as far as modality goes, the existence of an individual in different possible worlds is the same thing as having multiple logically possible/self-consistent propositions or predicates we can assert of that individual. MU "exists" in multiple possible words... because there are multiple propositions or predicates we can assert of MU that do not entail contradictions.

That's literally all that's going on here, "possible worlds" talk is just a different way of talking about contradiction and logical possibility. Which is admittedly confusing, since talking about the existence of possible worlds sounds like an ontological/existential claim... but its not.