I agree. True Marxism is about throwing the baby out with the bathwater, that is, everything we've done up to now has served its purpose and we're on our way to a new world.

Then I saw “a new heaven and a new earth,” for the first heaven and the first earth had passed away, and there was no longer any sea. 2 I saw the Holy City, the new Jerusalem, coming down out of heaven from God, prepared as a bride beautifully dressed for her husband. 3 And I heard a loud voice from the throne saying, “Look! God’s dwelling place is now among the people, and he will dwell with them. They will be his people, and God himself will be with them and be their God. 4 ‘He will wipe every tear from their eyes. There will be no more death’ or mourning or crying or pain, for the old order of things has passed away.” — Revelations 21:4

Note "the new heaven and new earth" is a quote from Isaiah.

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I was poring over your example trying to get that right.

Yes, but even the extension within worlds is artificial, because the worlds (possibilities) are imaginary. — Metaphysician Undercover

John asked if Frosty the Snowman is a Christmas themed character.

The extension of "is a Christmas-themed character" is

{Santa Claus, Mrs. Claus, Reindeer (especially Rudolph), Snowmen (like Frosty), Elves, Belsnickel & Befana, The Grinch, Jack Skellington, Ebenezer Scrooge}

C(x) = "Is a Christmas-themed character."

C(Frosty the Snowman) is true.

It doesn't matter that Frosty the Snowman isn't real.

Wouldn't you say that there is a sense in which Marxist or Marxist-inspired ideologies are supposed to be based on compassion for the victim or the oppressed or the disenfranchised? — Leontiskos

That's a good question. Strictly speaking, Marx was an apocalyptic prophet, not advising about how things should be, but predicting what will be. The proletariat are weaponized against the bourgeoisie with little regard for whether they're actually capable of running the world.

Maybe Marxism could be valued by someone who has compassion, but is it really based on compassion?

Vulnerable young British women — AmadeusD

Was somebody trying to be compassionate toward vulnerable British women?

So we have multiple domains and interpretations. That gives us extension within worlds, but not across worlds.

That is contrary to what the SEP article states. Modal logic is intensional. And, it is only the expression of it, the interpretation of separate "possible worlds", which produces extensionality. — Metaphysician Undercover

Could you quote the passage you're referring to here?

- So substitution fails across worlds, not because modal logic is intensional,
but because predicate extensions vary from world to world. — Banno

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So with Nixon winning the election, the domain is

{Nixon}

W(x) = won the election
L(x) = lost the election

W(Nixon) is true.

But in the possible world(s) in which he lost the election,

L(Nixon) is true.

Is that right?

You claimed Reagan created stability. I'm calling utter bullshit — creativesoul

I was talking about the stagflation crisis of the 1970s, which set the stage for the rise of Reaganomics, also called neoliberalism.

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How is the domain set?

They see it as what happens when the reformist left is undermined by corporate power and replaced with a form of politics that atomises or divides people into smaller interest groups, which ultimately serves those in power rather than challenging them en bloc. — Tom Storm

I can see that.

The older I get, the less certain I am. And the less I care, to be honest... — Tom Storm

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Where people stand politically is often a reflex action. How committed they are to the actual implications of their beliefs may be an entirely different matter. I know plenty of left-leaning people who might march on behalf of the homeless, yet if a homeless service tried to open a low-cost apartment building on their street, they could be even more vigorous in opposing it. — Tom Storm

Right, and that's the misalignment I was talking about in the OP. They're part of a political force that's trying to help people, but they actually despise people.

Maybe it’s less about compassion then and more about the role of government in society? — Tom Storm

It's definitely about the role of government, but they want a government that recognizes people's rights. They want a social safety net.

Could it be that the complaints have changed and that identity politics is annoying to them? — Tom Storm

Honestly, identity politics is heavily embedded in the older black people I know. They'll go to their graves that way.

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Just thinking out loud. Isn't the way conservatism functions different across cultures and contexts? There are conservatives on the left, for example, old-school class warriors who dislike the identity politics of the current left. They hope to conserve the left of the early to mid 20th century. In Australia, political conservatives generally support community welfare programs, such as pensions, unemployment benefits and free healthcare, while the radical right (a small boutique group) might oppose such programs. Perhaps the majority of Australians actually favor a form of progressive politics, so conservatism here may resemble the left in countries with a more libertarian (?) ethos. I'm not sure many lefties I know are especially compassionate. How does one gauge that? I don’t always go by their politics. I go by their behaviors toward others in real life. I think a lot of the left take a kind of rights-based perspective, which is somewhat separate from compassion. — Tom Storm

I wasn't arguing that conservative people are any less compassionate than their progressive brothers and sisters. My point was if you look at the rudder of a progressive boat, it's compassion. We shouldn't just let people suffer when we can help, and the government is the best way to coordinate that care.

You're right that conservatism is going to look different in different times and places, but isn't it true that conservatism is best typified by an older person? An older person has lost some of the compassion she might have felt earlier in life because she's been through hardship and survived. Hardship doesn't breed compassion ironically. It fosters a less romantic, more practical attitude. We don't need a perfect world. We need people who will buck up and figure out how to survive the world we have. If that world isn't too bad in terms of survivability, then why change it?

I'm thinking of elderly black people I know who, as you say, have the same political views they always did. But now that they're older, they're actually irritated by the complaints of young people. Maybe it's obvious why.

The stability of everyday working-class American lives, generation after generation was never better than the period between Roosevelt and Kennedy/Nixon. — creativesoul

I think you mean working-class white men.

1.2 Extensionality Regained

The idea of possible worlds raised the prospect of extensional respectability for modal logic, not by rendering modal logic itself extensional, but by endowing it with an extensional semantic theory — one whose own logical foundation is that of classical predicate logic and, hence, one on which possibility and necessity can ultimately be understood along classical Tarskian lines. Specifically, in possible world semantics, the modal operators are interpreted as quantifiers over possible worlds, as expressed informally in the following two general principles:

Nec A sentence of the form ⌈Necessarily, φ⌉ (⌈◻φ⌉) is true if and only if φ is true in every possible world.[3]
Poss A sentence of the form ⌈Possibly, φ⌉ (⌈◇φ⌉) is true if and only if φ is true in some possible world. — ibid

A quantifer tells us about the number of items in a domain that have a certain property, like all, or some. So "necessary" will mean that all the items (in every possible world) have the property. Possibly mean at least some of them do.

The possible worlds semantics creates the illusion of extensional objects, "worlds" as a referent. — Metaphysician Undercover

The kind of expression we're talking about is:

Necessarily, all John's pets are mammals.

There's no mention of possible worlds in this expression. So no, it's not that we give "worlds" a referent by modal logic.

This is the same tactic used by mathematical set theory. They use the concept of "mathematical objects" to create the illusion of extensional referents. It's Platonic realism. — Metaphysician Undercover

This is nonsense because numbers are already abstract objects. We don't need set theory for that. BTW, so are sentences, propositions, words, the whole shebang. We're examining the way we think. A few abstract objects show up. Deal with it. :razz:

Ok. I've got it.

Just a note on extension and intension. When I first learned about those ideas the word "definition" was attached.

An extensional definition of "John's cat" is John's cat, the actual fuzzy creature.

An intensional definition of "John's cat" would be more like a dictionary definition. It's the Siamese feline that belongs to John.

An extensional definition of "purple" is the set of all purple things. In other words, the extension of "purple" is not sense data, or some mental state, it's a set of all the things that can be described as purple.

An intensional definition of "purple" is a color on the high end of the visible spectrum, and so on.

So when we say modal logic wasn't extensional, it's that the items mentioned in modal expressions didn't pick out anything in the world. They had intensional definition, but that's all.

Do you agree with that?

Alright, then by statement do you mean a token of some proposition in some possible world? — NotAristotle

"Statement" and "proposition" are often used interchangeably. You just have to determine what the author means.

You are saying that a proposition is a statement that we all agree on? I have heard the term proposition applied in a more neutral sense. "The cat is on the mat" might be a proposition. It could be true; it could be false; it is not necessarily something we agree on. I think that is what you mean by "statement" however. — NotAristotle

No, I don't think a proposition is something we necessarily agree on. It's a truthbearer. It's the content of a thought or belief, for instance if John believes that grass is green, then the content of his belief is that grass is green, and that's a proposition. The alternative to propositions would be Davidson's system, which uses sentences.

The term "semantics" is a question mark for me here because semantics has to do with meaning, right? So how does meaning factor into a formal logical system? — NotAristotle

I think the point was to be rigorous about the meaning of certain statements, and that was lacking for modal statements. So they wanted a logical system that would specify the meaning of "It is possible that grass is green" or "It is necessary that grass is green."

but that a Tarskian interpretation of first order logic cannot be reconciled with possible world semantics. — NotAristotle

Why is that?

1. Possible Worlds and Modal Logic

In this first paragraph, the author of this article, Christopher Menzel, lays out the problem that possible world semantics was supposed to address:

In addition to the usual sentence operators of classical logic such as ‘and’ (‘∧’), ‘or’ (‘∨’), ‘not’ (‘¬’), ‘if...then’ (‘→’), and, in the first-order case, the quantifiers ‘all’ (‘∀’) and ‘some’ (‘∃’), these languages contain operators intended to represent the modal adverbs ‘necessarily’ (‘□’) and ‘possibly’ (‘◇’). — Possible Worlds, SEP

So the point was to add modal logic to first order logic. The problem was that modal logic had never been rigorously developed in the way first order logic had been, plus there was skepticism about its content:

A concomitant philosophical consequence of this void in modal logic was a deep skepticism, voiced most prominently by Quine, toward any appeal to modal notions in metaphysics generally, notably, the notion of an essential property. (See Quine 1953 and 1956, and the appendix to Plantinga 1974.) — ibid

Thoughts?

I’ve always had a hard time understanding the value of the possible worlds way of thinking about things. I read the first section of the SEP article and a little bit of the second section.

I am a self-avowed pragmatist. Can somebody explain how I might use model logic to solve problems or clarify concepts. — T Clark

Extending back to Socrates, there's an aspect of philosophy that is essentially a reflection on how we humans think. The highlights are points where we feel like we may have pulled the veil back on the underpinnings, or clarified something. The reasons a person might be compelled to explore this sort of thing are probably going to be personal, but with a connection to cultural events.

If you don't have this sort of need to understand, it's probably going to seem pretty useless. Your question reminds of the lament of the founder of Manichaeism that he was trying to make a new religion, but the local authorities were only concerned with whether or not he was healing people of disease. Diverging priorities. What can we do?

The introduction conceptually orients; "possible worlds" means something like - that that is opposed to the "actual world" such as a historical counterfactual, or perhaps, an agent acting differently than she or he actually did. — NotAristotle

Thanks for starting us out. I think you're right that we could think of possible worlds as opposed to actual, but in this context, we're following Leibniz, who allowed that the actual world is a possible world. What we would say is that the states of affairs associated with the actual world obtain. So they happened. This impacts the way we verify statements. We would say statements associated with the actual world will be verified by looking around us, so to speak. The statements of a possible world that does not obtain might have to be verified using logical or metaphysical possibility. For instance, in the possible world where Nixon lost the election, he wouldn't be living in the White House. You can imagine the various aspects of verifying that statement: "After Nixon lost, he wasn't living in the White House."

So we've brought up this terminology:

1. Statements
2. States of affairs
3. Verification
4. Obtain vs non-obtaining
5. Propositions

I'll note that I have an affinity for thinking in terms of propositions, which I think of referring to the elements of a community's bank of common ideas. I don't worry a lot about the ontological status of it, I don't know how it works. I just know it's part of how I think about ideas that count as abstract objects. They don't belong to me. They belong to the community. I can be wrong about them, and so on.

If we need to go back and explore any of the above terms, we can do that. Keep in mind that each one is a long rabbit hole, so we may start other threads if it becomes too boggy.

Thoughts?

I admire your confidence in being willing to tackle 60 intricate SEP pages about a generally controversial and deeply complex topic. — RussellA

Hey, how badly can we mangle it?

I know. After saying that it's probably just going to be me commenting on the SEP. :grimace:

Definitely worth pondering, yes

I understand greater need and greater suffering. But lesser suffering is still worth talking about and improving. Comparing suffering as if to triage the worthy from the worthless is counter-productive to building bonds between those who suffer. — Moliere

Ok. What practical bullet points emerge from this?

Ok. It was Moliere who asked. I'm sure he will be interested in your perspective.

You can look up information on it if you think the Australian system could benefit from America's greater experience and wisdom. I work in an emergency room so I'm up close and personal with the needs of my community. I have a list of local charities that I've collected over the years. They're all religious, go figure. People on disability don't need my list. Undocumented people is where the real need is.

Yeah, not so much. Leaves me pretty cold, really. :grimace: — Banno

Maybe if you walkabout in the desert it will help. :grin:

The American version has been around since the 1950s. — frank

Look I'm quoting myself.

These are people she has met personally.

And yes, we have also been involved in exposing scams. — Banno

Cool.

Come on, you know me better. Not I, Wife.

I'm not posturing, I'm pointing to a problem. And you did ask. — Banno

Your wife is a compassionate person. Hint to her to watch out for scams. It's hard to avoid them these days.

We've sent aid packages to folk we know in the US who have not been able to get the support they need. — Banno

You're such a compassionate person Banno. Thank you.

How would you say it stacks up to the USA's? Looks to be the same in terms of... — Moliere

I don't know. Everyone I've ever met who was living "on disability" (receiving SSI payments) was doing pretty well. Now does this mean they'll never have to be humble enough to ask for help? No. This isn't utopia. It's the real world. If you fall out of your power chair you're going to have to ask for help.