It's very neat. But yes, quite mad. — Banno

:lol:

Kripke was an essentialist: he believed individual identity was associated with its essence - a subset of an individual's properties.

So his theory of possible worlds is contingent upon essentialism being true. It falls apart if essentialism is false. My position has been that it is false. Can you defend essentialism?

As I understand it, for Lewis, it is not necessary to select one of the possible worlds as real, as all possible worlds are as real as each other. All possible worlds are real concrete worlds, actual ontological worlds. — RussellA

Yes that's exactly the problem. What we know as the independent, physical world, source of empirical observations, can no longer be accepted as such. It gets barred off as a sort of unreal illusion, and what we're left with is an extreme idealism where the ideas (possible worlds) are the reality. Something like this is necessary to fulfill the second truth condition listed by the SEP:

(ii) its designated “actual world” is in fact the actual world, — SEP

To fulfill the criteria for "truth", the actual world, within the possible worlds model, as one of the possible worlds, must "in fact" be the actual world. This is the issue @Banno and I debated endlessly in the other thread. The position that Banno insisted on, which I insisted is clearly false, is that the actual must be possible. This means that the actual world (and this is the factual "actual world") must be a possible world. Banno tried to dismiss this as an actual world which is distinct from the metaphysically actual world. But this means that the metaphysically actual world is not the true actual world, leaving the source of empirical observations as some sort of illusion.

Of course this creates a unique problem. We really only have empirical observations to base our stipulation of "actual world" on, in the modal model. But this realm of empirical observations is illusory, as it cannot be "the actual world". The actual world has to be one of the possible worlds. Then the use of empirical observations to produce "the actual world" in the model, is not justifiable. Then we have a whole number of concrete possible worlds, one of which is designated "the actual world" and is in fact the actual world by that stipulation, but the designation is unjustifiable.

So "infinite possibility" is the point: possible world analysis of an object has no bounds. — Relativist

Infinite possibility is the problem. Look at the first truth condition listed by the SEP:

(i) its set W of “possible worlds” is in fact the set of all possible worlds, — SEP

Since possibilities can be boundless, any set of possible worlds which we produce can never be "in fact the set of all possible worlds". And this is where the Platonist presumption becomes very clear. The possible worlds we present, are really ideas which we produce. But it is implied that there is an independent set of all possible worlds.

So this is precisely the problem with Platonism. We assume the existence of independent ideas, independent truths. But then for us to properly have truth, the ideas which we have, must be the very same as the independent ideas. This is impossible for us, and the impossibility manifests as this issue with infinity.

The opposite extreme: 100% of an objects properties (all of which are qualitative) at time t1 are necessary and sufficient for being that object at t1. This is my view. — Relativist

That is my view too, and I think it is the common understanding of "numerical identity", which is what the law of identity deals with. The issue I find is that ultimately, even this fails. We come to realize that it is impossible for us human beings, with our limited capacities, to completely understand all of an object's properties at t1. As devoted philosophers though, we want to know why we cannot understand all of a thing's properties at a specific time. Then we come to realize that the reason is that there is no such thing as t1, because time is always passing at any specified time. Therefore at any specified time, t1, there is actually duration, change is actively occurring. So "100% of an objects properties" doesn't quite fulfill "necessary and sufficient for being that object", because some parts are actively changing and those aspects of the thing cannot be described as properties.

As Aristotle pointed out, the parts which are changing defy the fundamental laws of logic, Because the object must either violate the law of noncontradiction (has and has not the property which is becoming), or violate the law of excluded middle (neither has nor has not that property). Aristotle demonstrated that what becoming, or change is, is fundamentally incompatible with "properties" of being. So properties are understood as form, and he proposed "matter" as potential, to represent that part of a thing which is changing, as the possibility for properties. From this perspective, at t1 (which must actually be a duration), an object consists of properties (form), but knowing all the properties will not produce a complete knowledge of the object, because the representation of t1 as a stopped point in time, cannot be true. Time is always passing, so a point in time, as t1, is a false representation which would properly be represented as a duration of time. In that duration of time change is occurring, and so we need to include "matter" as the potential, or the possibility for properties.

Kripke and I would say that "What if Nixon didn't win the 1972 election?" is a question about Nixon. — Banno

I explained the fault with this way of thinking explicitly, when we discussed "the circumstances" under which I was the fellow who won the lottery. Your statement is not about Nixon. Nixon won. Therefore to talk about a person who did not win is not to talk about Nixon. That's plain and simple.

To entertain the idea of NIxon not winning, is to think of different circumstances, just like if I was to think of myself as having won the lottery would be to think of different circumstances. Therefore "what if Nixon didn't win the 1973 election?" is clearly not a question about Nixon. It is a question about the circumstances. The question asks how would the circumstances be different if it had been the case that Nixon had not won. This is clear because you place "Nixon" within that context of the 1972 election, and you make a question about changing the context.

The opposite extreme: 100% of an objects properties (all of which are qualitative) at time t1 are necessary and sufficient for being that object at t1. This is my view.
— Relativist

That is my view too — Metaphysician Undercover

The implication is that there is only one possible world: the actual one. Do you agree?

When we conceive of (allegedly) possible worlds, we are constucting a fiction. IMO, the semantic framework can be useful for analyzing possibilities, but the exercise should not be taken too seriously.

It's not the case that logic necessarily implies metaphysics, but using metaphysical terms like "thing" and "identity" do imply metaphysics. And if you believe that epistemology can be separated from its metaphysical grounding you are mistaken. — Metaphysician Undercover

:up:

We both agree that there is a very clear and significant difference between "the actual world" in a modal model, and "the actual world" as a real, independent metaphysical object. However, you persistently refuse to apply this principle in you interpretation of modal logic. And, when I insist on applying this principle in our interpretation of modal logic, you reject me as erroneous, and refuse to include me in your "game". — Metaphysician Undercover

Yes, and this critique can be drawn out in various ways. The question of whether a first-order quantifier quantifies over imaginary entities has no real answer, and this is why modern philosophers can debate the topic ad nauseum. The underlying issue is the fact that modern philosophy is filled with metaphysical muddle. The attempt to devise a logic which leaves metaphysical questions untouched is incoherent. In the case of first-order logic this manifests with the metaphysical confusion surrounding ‘thing’ or ‘one’, which Aristotelians know to be transcendental terms but moderns confuse for category terms. The modern logician says, “For all x…,” but when asked what he actually means by ‘x’ he has no idea. He doesn’t know whether imaginary entities count, or whether theoretical entities count, or whether propositions themselves count, etc. In essence he does not know to which of the categories of being his quantifier is supposed to apply, and his presuppositions ensure that he will be unable to answer such a central question.

Kripke was an essentialist: he believed individual identity was associated with its essence - a subset of an individual's properties... So his theory of possible worlds is contingent upon essentialism being true. — Relativist

Yes, although in a way very different to others hereabouts. An individual's essence, for Kripke, consists in those properties that the individual has in every possible world in which it exists. Kripke does not start with a prior metaphysical theory of essences and then build modality on top of it. He starts with modal semantics (possible worlds, necessity, rigidity) and then derives essentialist claims as consequences of that framework. So the claim that “Kripke’s theory of possible worlds is contingent on essentialism being true” gets the explanatory order wrong. Essence is explained in terms of necessity, not necessity in terms of essence.

This means that the actual world (and this is the factual "actual world") must be a possible world. — Metaphysician Undercover

The alternative, as has been pointed out, is that for Meta the actual world is impossible.

The rest, again, mischaracterises and misunderstands modal logic.

the claim that “Kripke’s theory of possible worlds is contingent on essentialism being true” gets the explanatory order wrong. Essence is explained in terms of necessity, not necessity in terms of essence. — Banno

The "explanatory order" doesn't falsify the logic: there's s logical dependency on essentialism. But go ahead and explain essence.

Logic learned to free itself from ontology. Not entirely; the domain, and the notion of "something", remain. That's no bad thing. Those who cannot see the advances since the logic of Aristotle suffer a sort of intellectual myopia.

...there's s logical dependency on essentialism — Relativist

Again, that is the cart before the horse. For Kripke Essence is a consequence, not a beginning.

Yes that's exactly the problem. What we know as the independent, physical world, source of empirical observations, can no longer be accepted as such. It gets barred off as a sort of unreal illusion, and what we're left with is an extreme idealism where the ideas (possible worlds) are the reality. — Metaphysician Undercover

Davis Lewis in his Concretism presupposes an “actual world” that we live in and theorises about possible worlds where our counterparts live in. These possible worlds are also as “actual” as our world.

However, it is not part of his theory how we have knowledge of our “actual world”.

An Indirect Realist, such as Descartes, Locke, Leibniz, Hume and Russell, or a Phenomenologist, such as Husserl, would disagree that we can know an independent, physical world independent of empirical observations.

For the Indirect Realist and Phenomenologist, an independent, physical world is not barred off as an unreal illusion, and we are not left with an extreme idealism. The Indirect Realist is a believer in the concept of Realism, and the Phenomenonologist never doubts a reality behind the phenomena.

Wikipedia - Direct and Indirect Realism
Indirect perceptual realism is broadly equivalent to the scientific view of perception that subjects do not experience the external world as it really is, but perceive it through the lens of a conceptual framework

SEP - Phenomenology (Philosophy)
The epoché is Husserl's term for the procedure by which the phenomenologist endeavors to suspend commonsense and theoretical assumptions about reality (what he terms the natural attitude) in order to attend only to what is directly given in experience. This is not a skeptical move; reality is never in doubt.

For Lewis’s Concretism, it is not a problem as how we know the "actual world” that we live in, as this knowledge is presupposed, and outside the scope of his theory about possible worlds.

It is also not a problem as to how we can know possible worlds, as this is a theory. In the same way what we know about quarks is a theory, something that has such explanatory power that it is axiomatically assumed to be true.

SEP - Possible Worlds
His theory of worlds, he acknowledges, “does disagree, to an extreme extent, with firm common sense opinion about what there is” (1986, 133). However, Lewis argues that no other theory explains so much so economically.

Lewis’s Concretism attempts to analyse modal operators in non-modal terms using the theory of possible worlds. These possible worlds are as real, actual and concrete as the world we actually live in. The “actual” world we live in is presupposed and the possible worlds are theoretical.

SEP - Possible worlds
Furthermore, because worlds are (plausibly) defined entirely in non-modal terms, the truth conditions provided by Lewis's translation scheme themselves appear to be free of any implicit modality…………………Lewis's promises to provide a genuine analysis of the modal operators.

Yes that's exactly the problem. What we know as the independent, physical world, source of empirical observations, can no longer be accepted as such. It gets barred off as a sort of unreal illusion, and what we're left with is an extreme idealism where the ideas (possible worlds) are the reality. — Metaphysician Undercover

:grimace: I didn't see that coming!

I didn't see that coming! — frank

A thought:

It seems that it is impossible to understand something from the inside. One has to step outside in order to understand something.

For example, language cannot be understood using language, it can only be understood using a meta-language.

Similarly, modal logic cannot be understood using modal logic. Lewis’s Concretism was attempting this, even though it seems he failed.

SEP - Possible Worlds
Furthermore, because worlds are (plausibly) defined entirely in nonmodal terms, the truth conditions provided by Lewis's translation scheme themselves appear to be free of any implicit modality. Hence, unlike many other popular accounts of possible worlds (notably, the abstractionist accounts discussed in the following section), Lewis's promises to provide a genuine analysis of the modal operators.

Therefore, what is needed is another way to understand modal logic without using modal logic.

This is the issue Banno and I debated endlessly in the other thread. The position that Banno insisted on, which I insisted is clearly false, is that the actual must be possible. This means that the actual world (and this is the factual "actual world") must be a possible world. — Metaphysician Undercover

It seem that you and @Banno had incommensurable views. He was explaining Kripke's views, and I've benefited by getting a better understanding of what those views are. But to understand K, I think you have to understand what he is proposing. I proposed earlier that we think of the description of each possible world should be thought of as a book on a shelf; then the description of the actual world can be placed on that same shelf and thought of as a possible world along with all the others. We can take any book off the shelf and think of it as the actual world. So any world can be thought of as a possible world and that same world can also be thought of as the actual world.
Think of it this way. You are being asked to set aside the world as you know it and think about a different world. One's thinking in this mode involves suspending (bracketing) one's normal beliefs and disbeliefs. So, the world in which one is performing this thought experiment is set aside. While you are experimenting, we think of that world and the goings-on in it, as real. When we switch back to normal life, the actual world, in which all those books exist and we choose to take one off the shelf becomes, again, part of our thinking.
You may be thinking that this is all just pretending, but it is something was can do. It is how fiction ("Pride and Prejudice" or "Star Wars") works. You probably know Coleridge's phrase about the suspension of disbelief and his recognition that in some ways it is special, even weird. But it is clear that we can do it.
I don't think there is much difference, though, between thinking about a different world, in which, for example pigs and horses can fly and imagining that pigs and horses can fly. Kripke seems to think not.
That's why he proposes that we treat all possibilities in this same way. So perhaps we should only think of this as a fancy way of thinking about what would have been different if Nixon had lost the election. If it works for his project, it is justified.

Since possibilities can be boundless, any set of possible worlds which we produce can never be "in fact the set of all possible worlds". — Metaphysician Undercover

If possibilities can be boundless, it follows that they might not be. In that case, we can produce a set of all possible worlds. But we can define the set of all natural numbers, prove that it is infinite, and still calculate.

The possible worlds we present, are really ideas which we produce. But it is implied that there is an independent set of all possible worlds. — Metaphysician Undercover

The distinction between an idea and what it is an idea of what is sometimes called it's object, even though it may not be an object at all in the other sense of the word, is implicit in the idea of an idea. You seem to confuse the two when you say that the possible worlds are really ideas.
To understand this, may I go back to Frodo (just for the sake of an example).

Frodo" refers to Frodo, a fictional character in LOTR. It does not refer to the idea of Frodo.— Banno
A fictional character is an idea, not a thing. — Metaphysician Undercover

This is more complicated than it may appear. An idea is defined by reference to what it is an idea of. The idea has no existence without reference to its object. It is, in that way, parasitic on its object. But in some cases, the object of an idea may not exist, as in the case of Frodo. Here, we are presented with all the descriptions that we normally use to describe something in the world, but there is no such thing in the world. So, does Frodo exist or not? He is a fictional character, and so the answer must be, No. But there is an idea of him, which is created by the stories about him. So the answer must be Yes. Classic philosophical stuff, produced in the familiar way by extending the rules of a language game into a context where standard interpretations do not work, and we must decide how to apply the rules.
What we cannot do is say that Frodo is an idea, because ideas and people are objects of different categories. So we say, for example, that Frodo subsists or some such phrase. Perhaps better is to say that he is a fictional character, which means that he exists in the mode that fictional characters exist in, which, I accept, is to say nothing. In the end, we can work with this paradox without much trouble, so we do not need to resolve the problem, but only recognize it.
:LOTR is a possible world, in some sense of possible. So this problem, and its non-solution, apply to possible worlds, as well as fictional ones.
Do we want to say that possibilities exist or are real independently of our ideas of them? It could go either way. But what we cannot say is that ideas of possibilities can exist independently of the possibilities that constitute their objects. The dependence only goes one way.

The modern logician says, “For all x…,” but when asked what he actually means by ‘x’ he has no idea. He doesn’t know whether imaginary entities count, or whether theoretical entities count, or whether propositions themselves count, etc. In essence he does not know to which of the categories of being his quantifier is supposed to apply, and his presuppositions ensure that he will be unable to answer such a central question. — Leontiskos

I thought the point of modern-style logic was precisely to avoid metaphysical issues. Anything that is distinguishable as a distinct entity (within its category) can be substituted into the formulae, provided a suitable domain is defined for the variables. But the formal system is independent of that definition. Hence Quine's "To be is to be the value of a variable". Which doesn't solve any metaphysical problems, but then, I doubt if it was supposed to. But perhaps I've misunderstood.

Therefore, what is needed is another way to understand modal logic without using modal logic. — RussellA

We all use modal logic pretty regularly. This was just an effort to understand modal expressions extensionally. It seems to work pretty well. Obviously this kind of philosophy isn't for everybody. :grin:

The implication is that there is only one possible world: the actual one. Do you agree?

When we conceive of (allegedly) possible worlds, we are constucting a fiction. IMO, the semantic framework can be useful for analyzing possibilities, but the exercise should not be taken too seriously. — Relativist

There are so many different senses of "possible", and they are radically different, so I think using only one model in an attempt to understand all the different senses of "possible" would be a mistake. I believe, the big problem with "possibility" is the nature of time, and sorting out "time" is the best starting point.

At the present, looking forward in time, we have real ontological possibilities in relation to what may occur, and this affects our decisions on actions. In this case, "possible worlds" might be acceptable. If we believe in free will, rather than determinism, the possible worlds of the future can have real ontological status, as real possibilities.

At the present, looking backward in time, there is no ontological possibility in relation to what has happened. The past is fixed, and presents us with what actually is, as we understand the empirical observations which have occurred. This is why I hold a separation between what is actual and what is possible, ontologically one is the past the other the future, and for reasons very apparent from our experience, there is a significant (what I call substantial) difference between past and future.

That primary division, between what is actual and what is possible, (past and future), becomes complex in epistemology. If we look back in time to 1972, and say that it is possible that Nixon did not win the election, this is unacceptable because it contradicts what is actual. What we do in this case, is project the present back to a past time, 1972 in this case. And at the present there is ontological possibility toward the future, so we can talk about what could have happened if things had played out differently, when 1972 was the active present. This is fictional, because we cannot actually put the present back in time, to play things out differently. So this ought not be represented as "possible worlds", to distinguish it from real possible worlds looking forward in time. And we have a goof name for that "counterfactual" so we might call it counterfactual worlds.

Epistemological possibility becomes much more complicated though. We can look backward in time, and even though we assume that there is something which actually happened, we may not know what happened. So we can look at possibilities for what actually happened. This is not the same as counterfactuals because we do not know the actual. We might use "possible worlds" in this way, but notice that we cannot have "an actual world" in our representation, or else we violate the possibility of the others. And this is very similar to looking forward into the future, where there is no actual world, except in this sense we assume that there is an actual world we are trying to determine. In this case we would allow things designated as "truth" to enter into each possible world as a form of weighting.

In the case of looking forward from the present, at the possibilities for the future, we also must allow the weighting of what is judged as true. Certain activities, massive activities, like the movement of the earth provide significant weight for "truth", while tiny unruly bits of energy provide a lot of possibility.

Notice that in both cases where "possible worlds" may be appropriate, looking forward in time, being unsure of what will happen, or what to do, and looking backward in time, being unsure of exactly what happened, we must allow truth, or statements judged as true, to enter into each possible world to provide for weighting. So it is not the case that we would designate one world as the actual world, each world partakes of truth as a form of weighting to assist judgement. Each possible world has aspects within which are designated as true, and this assists us in choosing one of the worlds. The chosen world is still not the actual world, it is the chosen world.

The underlying issue is the fact that modern philosophy is filled with metaphysical muddle. — Leontiskos

Since most philosophers are not metaphysicians, the task of the metaphysician is to sort out that muddle created by the other philosophers.

The alternative, as has been pointed out, is that for Meta the actual world is impossible. — Banno

That's correct, "the actual world" refers to the real ontologically independent world, and it is impossible that we could get it into a possible worlds model. Even if we could represent the actual world with 1000% accuracy, and plug this into the model as "the actual world", that would be a representation, not the actual world.

So possible worlds semantics is stuck with the impossible situation (necessarily false), in which the designated "actual world" of the model, must in fact be the actual world. That plunges us deep into idealism where the real worlds are possible worlds, and the source of empirical observations, the supposed real independent physical world, is just an illusion because it cannot be "the actual world" because that has been subsumed by the model.

Logic learned to free itself from ontology. — Banno

Yes, ontology freed itself from the confines of the empirical world, and the metaphysicians have a word for this, it's "Platonism" .

Davis Lewis in his Concretism presupposes an “actual world” that we live in and theorises about possible worlds where our counterparts live in. These possible worlds are also as “actual” as our world. — RussellA

OK, but then "actual" has no real meaning. The world we live in isn't distinct as "the actual world", all the possible worlds are actual worlds, and there is no point to calling the world we live in "the actual world", because it's just one of many, which are more properly called possible worlds.

For the Indirect Realist and Phenomenologist, an independent, physical world is not barred off as an unreal illusion, and we are not left with an extreme idealism. The Indirect Realist is a believer in the concept of Realism, and the Phenomenonologist never doubts a reality behind the phenomena. — RussellA

That the world I live in and provides my empirical experience is "the actual world" must be an illusion. Use of "the" implies that it is the only. But if all the other worlds are just as actual, then that it is the only is an illusion. Now this produces the age old metaphysical question of why do I experience this world, and not some other. That is very similar to what Aristotle proposed as the fundamental ontological question. Instead of why is there something rather than nothing, which he dismissed as somewhat incoherent, he asked why is there what there is rather than something else.

So this way of looking at possible worlds doesn't really resolve anything. Instead of looking at the one actual world as "the one", and asking why there is this one rather than something else, it answers that question by saying that there actually is every other possibility. But we still have the same sort of question, why am I in this world, not in one of those others.

These possible worlds are as real, actual and concrete as the world we actually live in. The “actual” world we live in is presupposed and the possible worlds are theoretical. — RussellA

I think this is inconsistent with what you said above: "These possible worlds are also as “actual” as our world". If all the possible worlds are equally "actual", how could one be presupposed and the others theoretical? Doesn't this give unequal status to their actuality? But again, "actual" doesn't seem to have any meaning, so we could just flex it around.

I proposed earlier that we think of the description of each possible world should be thought of as a book on a shelf; then the description of the actual world can be placed on that same shelf and thought of as a possible world along with all the others. We can take any book off the shelf and think of it as the actual world. So any world can be thought of as a possible world and that same world can also be thought of as the actual world. — Ludwig V

This seems to produce the same problem as Lewis. Each possible world is equally "actual". But then "actual" has no real meaning. And if I ask, why have I experienced this world rather than any other world, there is no answer for me.

You may be thinking that this is all just pretending, but it is something was can do. It is how fiction ("Pride and Prejudice" or "Star Wars") works. You probably know Coleridge's phrase about the suspension of disbelief and his recognition that in some ways it is special, even weird. But it is clear that we can do it.
I don't think there is much difference, though, between thinking about a different world, in which, for example pigs and horses can fly and imagining that pigs and horses can fly. Kripke seems to think not.
That's why he proposes that we treat all possibilities in this same way. So perhaps we should only think of this as a fancy way of thinking about what would have been different if Nixon had lost the election. If it works for his project, it is justified. — Ludwig V

This is the problem. If those other possible worlds are known as fiction, and the one I live in is known as fact, then what's the point in saying that each one is fundamentally the same? Clearly we are giving one, the one we live in, a special status, so why try to dissolve that special status. The better way toward understanding is to emphasize that special status, and try to understand what it consists of. That's ontology. If some epistemology is trying to dissolve the special status, it's only being counterproductive.

The distinction between an idea and what it is an idea of what is sometimes called it's object, even though it may not be an object at all in the other sense of the word, is implicit in the idea of an idea. — Ludwig V

I know that as the distinction between an object, and a logical subject. We can take a subject, and make predications, and there is no need for an independent, physical object. If we show a relation of correspondence between the subject with its predications, and a physical object, and we say that the subject represents that object, we will judge this as truth.

There appears to a neglect of this separation between subject and object in some modern interpretations of logic. @Banno displayed this in his discussion of "Frodo". By mentioning "Frodo" as a subject, Banno claimed that it is implied that Frodo is an existing thing. But that dissolves the subject object distinction, (a subject is necessarily an object), thereby leaving the judgement of truth in Never-Neverland.

Classic philosophical stuff, produced in the familiar way by extending the rules of a language game into a context where standard interpretations do not work, and we must decide how to apply the rules.
What we cannot do is say that Frodo is an idea, because ideas and people are objects of different categories. — Ludwig V

It's not difficult. We just need to adhere to the subject/object distinction, which has been a rule for millennia. Why would we suddenly believe that it would be a good idea to dissolve the distinction? However, contrary to what you say, subjects are ideas. "Frodo", as a subject is an idea. Person is the predication of that subject, and we have the idea of a person. Since there is no corresponding physical person, it is a fictitious idea. "Nixon" on the other hand, as a subject (idea) has a corresponding physical person. So we can say whatever we want about "Frodo" without worrying about truth, though we ought to stay consistent with the model of the creator to avoid copywrite infringement. But in the case of "Nixon" we ought to respect the truth.