It was that, and hence my response regarding how you do not have direct epistemic access. If this access isn't infallible then there's no particularly superior access to your purported knowledge of the actual world over what is possible. — MindForged

This is like saying that a map with a misprint is not worth anymore than a possible map.

Do you ever stick to what you say or do you change it on a dime when an objection surfaces? Here's what you said before:

Yes, I used "possible" -- not essentially, but to avoid circumlocution. So, here's the same definition restated: "P is possible with respect to a set of facts, S, if P does not contradict the propositions expressing S." — MindForged

Touche! Fair enough. I was imprecise. Mea culpa. I had my doubts about "facts" when I typed it, but couldn't think of a better term. I thought of "set of propositions," but I wanted to be open facts in reality not yet discovered. So, try this one:

P is possible with respect to a set of facts or propositions, S, if P does not contradict S.

I do think "facts" should be restricted to intelligible reality.

The reason why you required infallibility (whether you acknowledge it or not) is because your initial claim in the OP was this:

First, it is unnecessary. As we can have no epistemic access to any world but our own, actual world, anything we can learn, we can learn from the real world. — MindForged

There is no claim of infallibility here. If you think there is, explain how.

The actual world is actual because it acts to inform us. Merely possible worlds do not act, let alone act to inform us. Instead, we inform (or perhaps misinform) them.

My point was that we don't have any better epistemic access to the actual world because of the limitations of perception. Without infallible means of accessing the states of affairs of the actual world, what we perceive to be the case can easily fail to be so. Whatever you mean by "direct access" is completely opaque, and so recourse to reliability here is equally so — MindForged

We have no access to any possible world. We only have access to our imagination, which can easily be inconsistent. What we know of the actual world cannot "easily fail" if we exercise due diligence. It fails occasionally, but it is usually interpretations and constructs that fail rather than experiential data.

I have said exactly what I mean by "direct access." I said that a sensory object's modification of our sensory state is identically our sensory representation of the object. I said that the object informing the subject is identically the subject being informed by the object. I said that a single act actualizes both the object's intelligibility and the subject's capacity to be informed. You have objected to none of these claims.

Possible worlds can do none of these things, because, being merely possible, they cannot act to inform us.

Possible worlds as a means to give semantics for possibility is not circular. The only way you could claim that is because the word "possible" is part of the name of the concept. — MindForged

It is the name of the concept because the employment of the tool requires one to construct, or at least recognize, worlds that are possible.

P is possible if there is at least one world in which P is the case — MindForged

This is inadequate as, unless P is actually true, there is no world in which P is the case. What you need to say is "P is possible if there is at least one possible world in which P is the case" -- and that is circular.

Possible worlds are not (unless you're David Lewis) being posited as literal other worlds in the same sense as the actual world. It's right there in the name, there's only one actual world. Venus in another possible world is still Venus as it might have been, the individuation conditions return the same object (that's why the names are a rigid designator). — MindForged

Obviously, possible worlds are not actual worlds. I do not imagine them to be so. Still, they are not our world, as, if they are different in any way, they are not identical to our actual world. Any world that is not identical to our world is a different world. As each is a different world, each (actual or potential) object in them is a different object from any object in out actual world.

Venus in another possible world is still Venus as it might have been, the individuation conditions return the same object (that's why the names are a rigid designator). — MindForged

Objects are individuated by the network of relations that contextualize them. If you change one relatum, you change the object's individuation conditions. So, the individuation conditions may not return the same object. E.g. if I am the oldest child in the real world and in the possible world I have an older brother, the individuation condition of being the oldest child will not return me.

Further, Venus as it might have been is no longer possible. Future contingents are possible. Past contingents have already past into necessity. It is possible that there will be a sea battle tomorrow or not, but the battle of the Coral Sea is history. Only in other worlds may similar events turn out differently.

"Second planet" and "morning/evening stars" are not proper names. — MindForged

No, they are not. There are the kinds of properties you called upon to justify the "rigid designator" property of a term many posts ago -- what you're calling "individuation conditions." (Which are relational descriptions.) And, in the case of my example, they do not return objects supporting your case.

the identity holds across worlds (i.e. trans-world identity) because they have the same essential properties which make it Venus. — MindForged

If they are properties, we can describe them.

Counterfactual propositions can be judged on the basis of real-world potencies. Steve would have enjoyed the trip even if he did not go on it because he is actually disposed to enjoy such trips. If we did not know his relevant dispositions, we could not say whether he enjoyed the trip or not. So, there is no need for possible worlds talk to deal with counterfactuals.

No, because I'm stipulating that it's the same glass of water. It's just that in the actual world it's H2O and in a possible world it's H2O2. — Michael

What matters is not the glass, but the material inside of it. If you stipulate that the same glass holds hydrogen peroxide instead of water, then you are supposing that it is not a glass of water, but instead one of hydrogen peroxide.

How is this any different to stipulating that I'm married to the same woman, but that in the actual world she's English and in a possible world she's American? — Michael

Because you are conflating between changing the property of the glass (i.e. as to what material it holds) with changing its contents, from one thing into another. It's fine to suppose the glass is different, and holds something else – what is more mind-boggling is to suppose that the water in the glass is hydrogen peroxide. If you were to ask me to do that, I'd have to say "I don't understand – which am I imagining, that it's water, or that it's hydrogen peroxide?"

It's also no contradiction to imagine that scientists have been mistaken (or lying) and that the chemical composition of water in the actual world really is H2O2. — Michael

Yes, but that's irrelevant. In that case, then 'H202' and 'water' would have meant the same thing, and we made a mistake in thinking that 'H20' and 'water' did. Nothing about Kripke's arguments change. Again, take an example you already agree with.

Things can have more than one name. The liquid we drink can either be called "water" (a common name) or "hydrogen peroxide" (a scientific name, referring to its chemical composition), so water and hydrogen peroxide are the same thing, and H2O is something else. This might be false, but it's not a contradiction. — Michael

The point is not about what names a thing can be given. Of course we can imagine that hydrogen peroxide was called 'water'. That wouldn't make it water – it would just have the same name that water now has. It would nonetheless be a distinct substance.

And 'hydrogen peroxide,' crucially, is not a name for water in the actual world.

Kripke would readily agree that the statement "Hesperus is Phosphorus" expresses a contingent identity in the case where "Hesperus" and "Phosphorus" are shorthand expressions for definite descriptions that merely happen to have the same reference in the actual world. — Pierre-Normand

ok

You seem very sensible, and I don't object to what you are saying.

I have no problem in saying that if I'm talking about possibilities with respect to an individual, I am still talking about that individual -- and that is true whether I am naming the individual or describing the individual. It does not matter if I say "Pierre," or "the man on the corner with the tan jacket." Even if the man moves and changes his jacket, I am still intending the same person.

My objection is a practical one against bringing in the unnecessary baggage of possible worlds to express such a simple idea.

Yes, but that's irrelevant. In that case, then 'H202' and 'water' would have meant the same thing, and we made a mistake in thinking that 'H20' and 'water' did. Nothing about Kripke's arguments change. Again, take an example you already agree with. — Snakes Alive

It's not irrelevant. It's the central point. If we accept that we could be mistaken in thinking that water is H₂O then we accept that "water" and "H₂O" don't mean the same thing and so that water isn't necessarily H₂O. If we accept that water might actually be H₂O₂ then we are saying that it's possible that water is hydrogen peroxide.

It's not irrelevant. It's the central point. If we accept that we could be mistaken in thinking that water is H2O then we accept that "water" and "H2O" don't mean the same thing and so that water isn't necessarily H2O. If we accept that water might actually be H2O2 then we are saying that it's possible that water is hydrogen peroxide. — Michael

Part of Kripke's point is that we can indeed be mistaken about necessary truths – that is, some necessary truths are a posteriori. You are trading on distinct notions of 'possible,' and one possible view, which is Kripke's, is that epistemic possibility (for all we know, water might have been H20) is distinct from, and has wider scope than, metaphysical possibility (water could not have been anything but H20, since it would have to have been not itself, which is metaphysically impossible).

I don't think myself that this is the right way to put it, since if Kripke is right, 'water is H20' just means 'water is water,' and we already knew this trivial proposition a priori. What we learned, if you like, and which is genuinely contingent and a posteriori, is that all along we referred to the same thing with both these words. This is just a fact about linguistic usage (which of course may be a substantive discovery with huge implications, since we resolve what we thought were two things into the true one just by learning this).

Saying that something is metaphysically possible just is to say that it isn't inconsistent with the way things can be in accordance with the constitutive rules that govern how those things fall under concepts. (For instance, it is a constitutive rule of bishops, in chess, that such pieces only moves legally along diagonals; and it is a constitutive rule of the concept of a human being that it is an animal). — Pierre-Normand

I understand what you are saying, but it is not how I'd define "metaphysically necessary." There is no metaphysical reason a chess bishop can't move like a knight, rook or in any other way. It is merely a convention.

I would say that metaphysical necessity can make no reference to contingent constrains. It is what is required by the nature of existence per se. For example, it is metaphysically necessary that a potential be actualized by something already actual, because actualization is an act, and only actual beings can act.

I think it can be shown that if "A" and "B" are meant to function in the way ordinary proper names are used, and they both actually name the same individual, then it is metaphysically necessary that A and B are numerically identical. — Pierre-Normand

I agree, because this is just an application of the ontological principle of identity.

But you don't know what you mean by "actual". Or, if you do know what you mean by it, you're keeping it to yourself. — Michael Ossipoff

By "actual" I mean operational or able to act.

As mere hypotheticals can't act, the aren't actually facts.

"Fact" is often or usually defined as a relation among things, or as a state-of-affairs. — Michael Ossipoff

OK. As long as the things and states are actual, I have no problem with this.

in what regard, in what manner, do you think this physical world is different from merely the setting for your hypothetical life-experience-story, consisting of a hypothetical logical system such as I've described? — Michael Ossipoff

Because a hypothetical story represents actions and states of affairs that did not occur.

I don't think myself that this is the right way to put it, since if Kripke is right, 'water is H20' just means 'water is water,' and we already knew this trivial proposition a priori. What we learned, if you like, and which is genuinely contingent and a posteriori, is that all along we referred to the same thing with both these words. This is just a fact about linguistic usage (which of course may be a substantive discovery with huge implications, since we resolve what we thought were two things into the true one just by learning this). — Snakes Alive

It seems to me that Kripke can avoid this problem since although "water" and "H2O", construed as co-referential natural kind terms, have the same reference, they can still be taken to have distinct Fregean senses. Hence someone may grasp (as Frege would say) the senses of both terms and not know that "water is H2O" is true, and a fortiori not know either that it's necessarily true. It's true that Kripke thought that he was improving on Frege with his conception of proper names and of natural kind terms; but that's because he though (wrongly in my view), as many other philosophers have thought, that Frege was committed to a descriptive theory of senses. Gareth Evans and John McDowell, among others, have argued that the Fregean senses of proper names and of natural kind terms are better construed as object dependent senses or, as they're also called, singular senses.

It seems to me that Kripke can avoid this problem since although "water" and "H2O", construed as co-referential natural kind terms, have the same reference, they can still be taken to have distinct Fregean senses. — Pierre-Normand

I suppose it is possible, but he would have to take the senses not to be the sort of descriptive entities that interact with the compositional semantics that they're often taken to be.

Honestly, I don't like Fregean senses, because they correspond to no consistent notion. All that seems to be appealed to in this case is the fact that different words can mean the same thing, and this can be opaque to us. If a 'Fregean sense' is just the word through which we grasp, or fail to grasp, a meaning, so be it: then all that's meant is that there's a way we get to a meaning, i.e. through the very word used to convey it.

I understand what you are saying, but it is not how I'd define "metaphysically necessary." There is no metaphysical reason a chess bishop can't move like a knight, rook or in any other way. It is merely a convention. — Dfpolis

The rules of chess indeed are arbitrary conventions but it is only thanks to those arbitrary conventions being what they are that the chess phenomena, and the chess pieces, likewise, are what they are. Chess games, and the objects that are involved in chess games, are socially constituted. There indeed are no metaphysical reasons why the rules of chess ought to be what they are, but given that they are what they are, (as they are agreed to be within some determinate community of chess players,) then, necessarily, the pieces that are being called bishops must be subjected to the normative rule that they ought to be moved along diagonals on the chess board. If they weren't thus governed, then, they might still be called "bishops", but in that case, "bishops" would designate the pieces of a different game. The sort of necessity involved can be called metaphysical since it refers to a necessary condition for the bishops of the conventional game of chess being what they are.

The problem is the common sensical notions won't be able to be used broadly to understand many instances of how we use modal concepts and so it fundamentally doesn't do the job we use possible worlds semantics to accomplish (that is, to give a rigorous account of these ideas) — MindForged

I am open to persuasion, as some clever people have spent a lot of time on possible worlds and modal logic, and I'm reluctant to believe that lots of clever people have wasted time on a chimera (although it does happen from time to time). What I've never seen, and it's not for want of looking, is what that field of inquiry achieves. It doesn't explain ordinary language, because people don't think in terms of possible worlds.

I'm still trying to find a demonstration of what it does clarify or explain.

I suppose it is possible, but he would have to take the senses not to be the sort of descriptive entities that interact with the compositional semantics that they're often taken to be. — Snakes Alive

For sure. Singular senses aren't shorthands for definite descriptions. But they are quite useful in accounting for the fact that co-referential names (or co-referential natural kind terms) can be used competently by a rational thinker who can wrongly believe them not to be co-referential (or be agnostic regarding that) without being deservedly charged with irrationality.

What I've never seen, and it's not for want of looking, is what that field of inquiry achieves. It doesn't explain ordinary language, because people don't think in terms of possible worlds. — andrewk

It's just a modeling tool. It has a potential to mislead or confuse, especially when the processes of model construction are misconceived, or the models are abusively reified (David Lewis, I'm looking at you!) But when used properly, talk of possible worlds can help make arguments regarding modal claims explicit. As such, it can be revealing of confusions that were already in play in philosophical discourses about necessity and possibility.

One area of philosophy that I am especially interested in is the debate on free will, responsibility and determinism. Issues of necessity and possibility abound, and confusions about them are endemic. Possible worlds are being used a lot in this literature, and although the arguments that they convey can be made without reference to possible worlds, their use by the proponents of various theories about the scope of the powers of rational agents often allows one to pinpoint what the specific flaws are in their conceptions of free (or unfree) agency.

Yes, but that much is obvious from the fact that words mean things, and what they mean might be opaque to their users. Invoking a dubious notion like Fregean senses is probably not a good idea, unless this obvious fact is all one means by it.

Yes, but that much is obvious from the fact that words mean things, and what they mean might be opaque to their users. Invoking a dubious notion like Fregean senses is probably not a good idea, unless this obvious fact is all one means by it. — Snakes Alive

I am unsure why you think that the notion of Fregean sense is dubious. For one thing, it appears to solve the problem that you raised for Kripke regarding the possibility that one may fully understand the meaning of "Water is H2O" and not know a priori that it is true.

Because the fact that we might not know what words mean already solves this problem, and the Fregean sense, if it is something more than this, adds nothing to the explanation. The literature on Fregean senses is very confused, and the notion is ill-defined and has led to a lot of pointless back-and-forth.

There are in fact at least three things that Frege might have meant by a 'sense,' including Carnapian intension, Kaplanian character, and Stalnakerian information about the meaning of a word given that it was uttered in some context or other. We already have notions for all these things; introducing 'Fregean senses,' which have never been adequately delineated anyway, doesn't help.

"But you don't know what you mean by "actual". Or, if you do know what you mean by it, you're keeping it to yourself." — Michael Ossipoff


By "actual" I mean operational or able to act. — Dfpolis

Characters in a story act on eachother. Are they actual?

Maybe best to stick with Lewis's definition of "Actual":

"in, of, part of, or consisting of, the physical world inhabited by the speaker".

By that definition, this physical world is "actual" when spoken of by you, even if it's entirely hypothetical with no objective existence. If you think it has objective existence, then what do you mean by "objective existence"?

As mere hypotheticals can't act, they aren't actually facts.

There are genuine abstract facts about hypotheticals.

" "Fact" is often or usually defined as a relation among things, or as a state-of-affairs". — Michael Ossipoff


OK. As long as the things and states are actual, I have no problem with this.

No, that isn't part of the definition. A fact can be about things that are entirely hypothetical, and which aren't actual to anyone in this physical universe.

"If there were Jaberwockeys, Slitheytoves, and the property of being brillig, and if all Slithytoves were brillig, and all Jaberwockeys were Slitheytoves, then all Jaberwockeys would be brillig."

"in what regard, in what manner, do you think this physical world is different from merely the setting for your hypothetical life-experience-story, consisting of a hypothetical logical system such as I've described?" — Michael Ossipoff


Because a hypothetical story represents actions and states of affairs that did not occur.

Wrong. The story's actions occurred in the story. You haven't said in exactly what manner this physical world is more than the setting of that hypothetical experience-story. Things occur in your experience-story.

What's a test-able difference between things occurring in your experience-story as I defined it, and things "actually" occurring?

That's what I'm asking when I ask you what you mean.

Tomorrow morning I'll reply to your posts that I haven't replied to yet.

Michael Ossipoff

water could not have been anything but H20, since it would have to have been not itself, which is metaphysically impossible

...

What we learned, if you like, and which is genuinely contingent and a posteriori, is that all along we referred to the same thing with both these words. — Snakes Alive

We also refer to the same thing using the words "Donald Trump" and "the 45th President of the United States" but don't say that if Donald Trump wasn't the 45th President of the United States then he wouldn't be himself.

So how do we determine which words are rigid designators – which words refer to the same thing in all possible worlds – and which don't?

Your answer before was that it's just a matter of stipulation. We stipulate that the 46th President in a counterfactual scenario is "the same" Donald Trump who is the actual 45th President, so why can't we stipulate that H₂O₂ in a counterfactual scenario is "the same" water which is actually H₂O? There's this implicit premise that some properties are "essential"¹ to a thing's identity and others contingent, but how do we determine which properties are which? You say that the chemical composition of water is an essential property, but perhaps that the material of the Taj Mahal isn't (and so it could have been made of wood, even though when we refer to the Taj Mahal we're referring to a building made of things other than wood)?

¹ Edit: Yes, here's an article that discussess Kripke's and Putnam's "natural kind essentialism".

speaking of worlds as simply "possible" allows one to confuse logical, physical and ontological possibility. — Dfpolis

...distinctions whose advocates can't specify what they mean by them — Michael Ossipoff


I can. I said :

"P is possible with respect to a set of facts, S, if P does not contradict the propositions expressing S." — Dfpolis


Logical possibility means the proposition is consistent with S = the facts we know.

Physical possibility means the proposition is consistent with S = the laws of nature.
Alternately, one may mean the proposition is consistent with S = the laws of nature plus the facts we know about a physical state.

Ontological or metaphysical possibility means the proposition is consistent with S = the nature of being qua being. — Dfpolis

Your symbolic jargon is getting in the way of your knowing what you're saying. Better to say it in English.

So, without the jargon, can you say what it would mean to say that this physical world has physical or ontological reality or existence that the hypothetical logical system that I described doesn't have?

And if you say that the difference is that this physical world is "actual", then of course I'll ask what you mean by "actual". ...I mean I'll ask if you have a better answer than your previous one.

Is there a physics experiment that can establish that this physical world is other than a logical system, a system of logical and mathematical relation--as physicist Michael Faraday suggested in 1844?

Michael Ossipoff

”You believe in an un-acknowledged and unsupported assumption that the physical world that we live in is the "actual", "existent", "physical" and "real" one, in some (unspecified) sense in which the infinitely-many other possibility-worlds aren't.” — Michael Ossipoff
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I do not deny the existence of other universes in a multiverse

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I agree with the usage of those who define “this universe” as our Big-Bang Universe (BBU), and any physically-inter-related multiverse of which it is part. In other words, the BBU and all else that it’s physically-related to. Physical relation includes origin, common-origin, shared spatial-continuum, physical influence or interaction.
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, or even independently.

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I interpret that as referring to other possibility-worlds, logical systems. Our physical universe is one of infinitely-many such logical-systems—or at least there’s no reason to believe otherwise.
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As David Lewis suggested, each such physical possibility-world is “actual” for its inhabitants (if it has any). The word “actual” is best defined as an adjective to denote the physical possibility-world in which the speaker resides.
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I am only saying that, as we are not in dynamic contact with them, they are epistemologically irrelevant.

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…whatever that means. Their “existence” as systems of inter-referring abstract implications is uncontroversial. They’re relevant because we live in one of them.
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”there's no reasons to claim that they're [the physical possibility-worlds]"real" or "existent", whatever that would mean.” — Michael Ossipoff
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Anything that can act in any way exists. That is sufficient reason to think that things that act to inform me are real.

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By your definition, then, hypothetical physical worlds are real, because their constituent things act on eachother.
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”There's no reason to believe that your experience is other than such an abstract logical system.” — Michael Ossipoff
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Of course there is. The things I experience act on me and I am aware of their action on me. Abstract logical systems do not act on me in the same way.

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That’s circular. It assumes that your experience-story itself isn’t an abstract logical system.
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Of course your experience is of things acting on you. That’s your experience-story. It’s about the interaction between you and your surroundings. It’s about your surroundings acting on you. That hardly can be given as a reason to say that it’s more than a hypothetical story about you and your surroundings’ interaction with you.
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”If you claim that this physical world is more than the setting for the hypothetical logical system that is your experience-story, then in what respect to you think that this physical world is more than that.” — Michael Ossipoff

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Because mere hypotheticals can't act on anything.

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Of course they can. They can and do act on other hypotheticals, including the physical animal that you are, in a hypothetical experience story about the experiences of that physical animal in its physical surroundings.
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”Do you believe in unparsimonious brute-facts and unverfiable, unfalsifiable propositions?” — Michael Ossipoff
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No.

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Good. Then you don’t believe in an “objectively existent” (as opposed to hypothetical) physical world whose existence you can’t explain, and whose more-than-hypothetical “reality” and “objective physical existence” you can’t define.
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In other words, you aren’t a Materialist. Good.
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Michael Ossipoff

I want to thank all the participants of the thread for an illuminating discussion and some of you for correcting some ignorant misunderstandings on my part.

Dennis

We also refer to the same thing using the words "Donald Trump" and "the 45th President of the United States" but don't say that if Donald Trump wasn't the 45th President of the United States then he wouldn't be himself. — Michael

That's exactly the point. 'The 45th president....' etc., is not a rigid designator.

So how do we determine which words are rigid designators – which words refer to the same thing in all possible worlds – and which don't? — Michael

It's an empirical question – you run the arguments, and see whether the denotation of the term shifts beneath modal operators, for example. So, 'Donald Trump might not have been the 45th president' is unobjectionable, but 'Donald Trump might not have been Donald Trump' sounds like a contradiction. This is because, so the argument goes, 'the 45th president' picks out relative to a world whoever is the 45th president, whereas 'Donald Trump' just picks out the same guy regardless.

A possible world where the 45th president (in that world) is non-identical to Donald Trump is unobjectionable, but what we're supposed to imagine as to a world where Donald Trump is not Donald Trump, i.e. not himself...this is less clear.

Your answer before was that it's just a matter of stipulation. We stipulate that the 46th President in a counterfactual scenario is "the same" Donald Trump who is the actual 45th President, so why can't we stipulate that H2O2 in a counterfactual scenario is "the same" water which is actually H2O? There's this implicit premise that some properties are "essential"1 to a thing's identity and others contingent, but how do we determine which properties are which? You say that the chemical composition of water is an essential property, but perhaps that the material of the Taj Mahal isn't (and so it could have been made of wood, even though when we refer to the Taj Mahal we're referring to a building made of things other than wood)? — Michael

No, we are not stipulating anything – that is how the language works, independent of our desires. If we say 'suppose Donald Trump were...' then because 'Donald Trump' is a rigid designator, we are already talking about how that very guy would be in some alternate situation. There is no question of 'how to determine' which guy in another world is him. The point is that proper names already pick out the same person 'across' possible worlds, so to talk about people using proper names in counterfactual scenarios is already to talk about one person as they might have been in various scenarios.

This is not what happens with definite descriptions. Again, we don't stipulate this – this is simply how definite descriptions work, independent of what we say about them. 'Suppose the 45th president were...' does not entail that we're talking about the same person across situations (on the relevant de dicto reading).

Here are some environments you can use to test for rigid designation across possible worlds:

Attitude contexts, such as belief reports: with non-rigid designators, these tend to have de dicto/de re ambiguities. With rigid designators, there tends to be no such ambiguity.

So if we say 'John believes that the president is a fool,' then this has two potential ways of being construed. First, it means that the actual president, Trump, is such that John believes him to be a fool. This may be true, even if John does not know that Trump is the president.

On the other hand, John might believe that the president, whoever it is, is a fool – he may believe this even not knowing that the president is Trump. The idea here is that if you look at all the worlds 'compatible' with John's belief, in each such world the president at that world, whoever it is, is a fool. But Trump is not necessarily a fool in all of them.

Notice that the same construction with a proper name lacks this second reading: 'John thinks that Trump is a fool.' This can only mean that John thinks of some individual, namely Trump, that he is a fool. Which individual he attributes the quality to does not 'shift' across worlds compatible with his belief.

–––––

Counterfactuals: 'If the president were a fool....' has a reading on which we're to imagine that the president, whoever it is, not necessarily Trump, is a fool. Compare 'If Trump were a fool...' no such reading. We are only bid to imagine scenarios in which the one individual picked out is a fool.

–––––

Modals: 'The president must be a fool.' This can be said even if one isn't sure who the president is, but that whoever it is, potentially different people in different scenarios, that person is a fool. 'Trump must be a fool' can't be used this way – it can only mean that this one guy, Trump, must be a fool (whether he is president or not).

–––––

Questions: 'Is the president a fool?' This may be asked felicitously even if the asker does not know who they are asking about. They simply want to know whether the president, whoever that happens to be, is a fool, and so not necessarily any information about a single individual. 'Is Trump a fool?' cannot be read this way.

Regarding the de dicto/de re interpretation, suppose that my house is made of brick. As I understand your position, under a de dicto reading it is acceptable to say that my house could have been made of wood, but under a de re reading it wouldn't, as it would be a contradiction to say that the bricks which are my house could have been wood.

The question, then, is whether or not there is an analogous de dicto reading of "water is H₂O" such that a counterfactual chemical composition of water is not a contradiction. Given that you've accepted that it's possible that scientists are mistaken in their claim that water is H₂O, isn't that an acceptance of such a de dicto reading (else it would be as incoherent as suggesting that we could be mistaken in thinking that Donald Trump is Donald Trump)?

It seems to me that possible worlds talk is unnecessary, circular and a source of possible confusion.

First, it is unnecessary. As we can have no epistic access to any world but our own, actual world, anything we can learn, we can learn from the real world. — Dfpolis

Right at the beginning, you include assumptions such as "actual world" and "real world". What are these worlds, and where is your justification for their "real" or "actual" existence? These assumptions are unjustified and unjustifiable. It seems possible that, as a result, your following arguments cannot deliver reliable conclusions, can they? :wink: :razz:

Right at the beginning, you include assumptions such as "actual world" and "real world". What are these worlds, and where is your justification for their "real" or "actual" existence? — Pattern-chaser

I responded to this question at length in my 5th post on the thread (a response to MindForged). He did not respond to the points I made on this topic. If you wish to respond to those points, I will be happy to discuss them with you.

Of course we have access to our own world. — Dfpolis

Yes, but we don't have Objective access, so everything you say about "the world" is necessarily speculative, and will always be so. :chin:

I largely agree with you. I'll just quibble a bit and add something else.

It seems to me that possible worlds talk is unnecessary, circular and a source of possible confusion.

First, it is unnecessary. As we can have no epistic access to any world but our own, actual world, anything we can learn, we can learn from the real world — Dfpolis

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Except for David Lewis and a few others, most philosophers do not think that possible worlds are literally real worlds that they inquire about. They think of possible worlds as more akin to logically consistent stories about how things might be.

Some philosophers think that Philosophy involves making "discoveries" about "possible worlds", which is a dramatic and perhaps even mystical way of saying that philosophers try to uncover necessary truths - propositions the negation of which is contradictory. I do not think philosophers do that either, for the most part. The fundamental issues in Philosophy do not seem to me to be of that kind.

Second, if the purpose of possible worlds talk is to define the meaning of modal statements, it is circular. If a person does not understand modality, they will not understand the meaning of "possible worlds."

I agree, and who actually has difficulty understanding modal statements anyway? Are there people who don't understand statements like "I would have had cereal this morning, but we had none left"?

Third, speaking of worlds as simply "possible" allows one to confuse logical, physical and ontological possibility. If one is thinking of a specific other world as possible, it is not clear that what is imagined to be possible will be self-consistent. For example, the calculations undergirding the fine tuning argument show that even small deviations from the real world may have unexpected and possibly unforeseeable consequences. If one is using possible worlds talk to justify Bayesian subjective probabilities, that can't be done without specifying a density of states for which we can have no objective justification.

I think possible worlds talk is usually intended as talk about logical possibility. I can't remember an article in which that isn't quite clear.

Despite my quibbles, I dislike possible worlds talk as well. Contemporary philosophers like to invent technical language to discuss their ideas. There is nothing wrong with that, if it is necessary. But quite often, philosophers will use technical language where plain language would do, and this has the effect of making philosophy seem incredibly convoluted to those outside of it, and even leads to errors for those within it. I think possible worlds talk is like this.

Thus, possible worlds talk is near the top of the list of philosophical worst practices.

Put it with talk of "analysis" and "intuitions"!

PA

without the jargon, can you say what it would mean to say that this physical world has physical or ontological reality or existence that the hypothetical logical system that I described doesn't have? — Michael Ossipoff

The "symbolic jargon" was not used to define the real world, but "possible."

I have said earlier, that the referent of "reality" is what is experienced in reliable experience. there is nothing exotic about "reliable" here. It just means that our experience is not delusion as commonly understood in psychology and medicine.

Yet, even the experience of a pink elephant is an experience of reality. It's just not an experience of external reality. The reality experienced in the pink elephant case is probably the effect of alcohol intoxication. A person familiar with severe alcoholism would interpret it so.

The sense of "real" is being capable of acting in any way. So, what acts to inform me is real by this definition.

So, I know physical reality is real because it can act on my senses (is sensible). Hypothetical systems cannot act on my senses in that way, and so have no reality outside the mind thinking them.

Is there a physics experiment that can establish that this physical world is other than a logical system, a system of logical and mathematical relation--as physicist Michael Faraday suggested in 1844? — Michael Ossipoff

Metaphysical questions are outside the competence of physics. However, every laboratory experiment observes actions and so confirms the reality of is objects.

And if you say that the difference is that this physical world is "actual", then of course I'll ask what you mean by "actual". — Michael Ossipoff

I already said, "By 'actual' I mean operational or able to act."

You asked if actors acting are actual. Of course they are. They're doing things.

If you want to know if mental constructs (hypothetical systems) are actual, of course they are, but as intentional, not physical, objects. They do not act on our senses, but in our minds.

or even independently.

I interpret that as referring to other possibility-worlds, logical systems. — Michael Ossipoff

That is not what I meant. I meant that there could be universes with no dynamic connection to ours in which things act on each other -- as opposed to the the mere possibility of such a system.

As David Lewis suggested, each such physical possibility-world is “actual” for its inhabitants (if it has any). The word “actual” is best defined as an adjective to denote the physical possibility-world in which the speaker resides. — Michael Ossipoff

No one resides in merely possible universes for the simple reason that "merely possible" means that they do not actually exist or contain actual objects. In other words, there are no actions or operations happening in them. Their only reality is intentional -- in the mind imagining them.

I am only saying that, as we are not in dynamic contact with them, they are epistemologically irrelevant.

…whatever that means. Their “existence” as systems of inter-referring abstract implications is uncontroversial. They’re relevant because we live in one of them. — Michael Ossipoff

It means that only objects we are in dynamic contact with can act on us to inform us. So, objects that cannot act on us (that we are dynamically isolated from) can't inform us and so are epistemologically irrelevant.

Of course abstractions do not interact. They can only inform our mind, so that our mind (not the abstractions) acts in a certain way. Therefore your claim is baseless.

It is unparsimonious to posit the existence of objects that can't act to inform us.

We live in a universe that can act to inform us -- not one that cannot.

By your definition, then, hypothetical physical worlds are real, because their constituent things act on eachother — Michael Ossipoff

This is incorrect. Since hypotheticals have only intentional existence, they have no acts of their own. Any acts associated with them are the acts of the mind thinking them -- not acts of the hypotheticals. If you conceive them to have acts, the only real act is you conceiving.

That’s circular. It assumes that your experience-story itself isn’t an abstract logical system. — Michael Ossipoff

Abstractions are the result of attending to some notes of intelligibility present in experience to the exclusion of others. So, the existence of abstractions, and of abstract systems, is logically dependent upon the existence of intelligible experiences. Thus, the experienced world is logically prior to any abstract world you may hypothesize.

Looked at in a different way, my experience of reality is that reality informs me -- sometimes in very surprising ways. My experience of hypotheticals is that I inform them our of my wealth of experience and am never surprised.

That hardly can be given as a reason to say that it’s more than a hypothetical story about you and your surroundings’ interaction with you. — Michael Ossipoff

I have just explained why experience is prior to any hypothetical story.

Of course they can. They can and do act on other hypotheticals, — Michael Ossipoff

No, they don't. Any action you hypothesize is your action, not the action of the hypothetical.

”Do you believe in unparsimonious brute-facts and unverfiable, unfalsifiable propositions?” — Michael Ossipoff
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No.

Good. Then you don’t believe in an “objectively existent” (as opposed to hypothetical) physical world whose existence you can’t explain, and whose more-than-hypothetical “reality” and “objective physical existence” you can’t define. — Michael Ossipoff

Of course I know (not merely believe) that there is an objective reality because I am involved in any number of subject-object relations that could not exist absent object that can act to inform me.

As for explaining the existence of contingent reality, sound deduction shows that it is maintained in being by a necessary Being whose essence is its existence.

I have defined all of the terms you have questioned and pointed out phenomenological differences between reality and your hypothetical systems.

Finally, no, I am not a materialist. I maintain the existence of intentional operations irreducible to physical operations.