However, what would something metaphysically impossible but logically possible be? — Lionino

If Kripke is to be believed then any a posteriori necessity is metaphysically necessary even if not logically necessary, and so their inverse is metaphysically impossible even if logically possible.

However, what would something metaphysically impossible but logically possible be? — Lionino

How do you understand “metaphysical possibility”? As 1) possible iff it is true in at least one logically possible world, as 2) possible iff it is logically consisted to the laws of some particular metaphysics, or 3) as a possibility not addressed by either (1) or (2) as just described?

If (1), and if all logical possibilities pivot on the laws of thought as I believe they do, then it so far seems to me that any possibility one can think of which conforms to the laws of thought will also be metaphysically possible. If so, then one cannot have a metaphysical impossibility that is however logically possible.

If (2), then this will depend on the laws of the particular metaphysics in question. For instance, in the metaphysics of epiphenomenalism it is impossible that consciousness could alter its constituency of brain via the choices consciousness makes, this despite such top-down process being logically possible all the same.

I'm quite open to learning about possibilities that would be encompassed by alternative (3), however.

The mathematics supporting quantum mechanics is entirely logical. But, although there are various metaphysical interpretations of QM, are there metaphysical analysis of this particular math structure?

The metaphysics of mathematics seems to be the existence of a mathematical object in a mathematical structure. Not the structure itself.

I'm not quite sold on modal metaphysics, at least not as distinct.
There are incompatible metaphysics that each are unverifiable and unfalsifiable.
Metaphysics could be who-knows-what, just not contradictory, so that's the logic part.
Are all such metaphysics possible, then?
By Chalmers, logical = metaphysical; by Shoemaker, metaphysical = physical.
Anyway, examples would help.

A metaphysical impossibility such as 'an infinite person' is logically possible, no?

what would something metaphysically impossible but logically possible be? — Lionino

Hmmm…..metaphysically impossible. If metaphysics is the doctrine of thought, the metaphysically impossible indicates a impossible thought. Any thought that occurs must be possible, but those thoughts that do not occur are not thereby impossible. Maybe they just haven’t happened yet.

If logic is the method of thought within the doctrine, then logically impossible just indicates an error in the method.

My guess: anything metaphysically impossible is logically impossible, but anything logically impossible must be metaphysically possible.

However, what would something metaphysically impossible but logically possible be? — Lionino

It's logically possible that the person who is posting as wonderer1 right now is not the same person as posted previously as wonderer1. However it isn't metaphysically possible.

Agreed, it seems that (1) does not allow for it while (2) does. I also thought of epiphenomenalism when thinking about this matter. I posted the thread to see what others had to say, as the internet gave lukewarm responses to it. But I kept the doubt in mind: is it not a matter of semantics even then? Because in epiphenomenalism, the mental changing the material is impossible within that metaphysics. But in epiphenomenalism, isn't the inability to change the material part of the definition of what is mental? And thus the mental changing the material becomes a logical contradiction within that metaphysics? Maybe that discussion ultimately boils down to some analytic X synthetic distinction, but I am eager to hear your take on it.

A metaphysical impossibility such as 'an infinite person' is logically possible, no? — 180 Proof

I am not sure what that means to be honest. Could you elaborate?


I guess it is true, depending on the philosopher, we will see metaphysics overlapping with either physical or logical. Some thinkers even deny metaphysics altogether. Some examples have been given in this thread, I think the epiphenomenalism one is interesting.

However it isn't metaphysically possible. — wonderer1

How so?

I came across Kripke and a posteriori necessity in my brief reading on the topic before making this thread. While I find his ideas very interesting and convincing even, I think the thesis is a bit too recent to make any definitive claims on it as a layman.

I came across Kripke and a posteriori necessity in my brief reading on the topic before making this thread. While I find his ideas very interesting and convincing even, I think the thesis is a bit too recent to make any definitive claims on it as a layman. — Lionino

Naming and Necessity is 43 years old now. Certainly "recent" when compared to Plato, but it's not like we're talking about last year.

But I kept the doubt in mind: is it not a matter of semantics even then? Because in epiphenomenalism, the mental changing the material is impossible within that metaphysics. But in epiphenomenalism, isn't the inability to change the material part of the definition of what is mental? And thus the mental changing the material becomes a logical contradiction within that metaphysics? — Lionino

For what it’s worth, my current thought process on the matter is along these lines:

Logical possibility—all of it pivoting on laws of thought—pivots on what is (taken to be) ubiquitous to all subjects of awareness. This irrespective of whether subjects of awareness might hold a comprehension of what these laws of thought might be; e.g., a preadolescent child will think via the laws of thought (however imperfectly and, hence, at times, illogically) although not holding a comprehension of them.

Physical possibility—when divorced from any metaphysics regarding what the physical entails, e.g. materialism, idealism, or substance dualism, etc.—also pivots on what is (taken to be) ubiquitously applicable to all subjects of awareness. Here, though, without a metaphysics there cannot occur a comprehension by which to make sense of physicality.

So both the logically possible and the physically possible will at root address ubiquitous actualities, actualities that are thereby universal and, in this sense, singular.

Metaphysics, on the other hand, will always make use of the logical and of the physical—at least in part, to which experiences, i.e. subjective actualities, can be added as well—to arrive at understandings regarding that which is in any way actual (including, for example, that which is actually possible). There are multiple ways metaphysics could be derived via physicality-bound (as well as, at times, experience-bound) logic. Thus resulting in multiple, often enough contradicting, metaphysical models of what is.

Each metaphysical system will then galvanize its own semantics; most of the time the validity of these metaphysics-specific semantics will be evaluated by their individual explanatory power—this in explaining what is actual (be it laws of thought, be it the physical, or be it our sometimes discordant and sometimes commonly held experiences, which could then extend into things such as cultures, languages, etc.). And, by extension, these individual explanatory-power-endowed semantics that together form the given metaphysics then grants the given metaphysics as a whole its explanatory power.

So the individual understandings, or semantics, imbedded within a metaphysical system (such as that of epiphenomenalism’s impossibility of mind affecting matter) is tied into, and is justified via, a webbing of ideally fully self-consistent semantics—all minimally conforming to what is known of logic and of physicality—that work together to explain all that is actual. To deprive epiphenomenalism of the impossibility of mind affecting matter is to then nullify the entirety of the metaphysical webbing of understandings which epiphenomenalism is. This, were it to occur, would then leave a vacuum of explanatory power and, hence, of general understanding, for all those that previously upheld the metaphysics of epiphenomenalism.

This being a longer path toward saying that I fully agree metaphysical differences can be said to boil down to semantics. I’d only add that, for one example, the particular semantic of “mind” in the case of epiphenomenalism appears to me inextricably bound into the entire webbing of semantics—of logic- and physicality-bound understandings—which this one metaphysics in fact is, if not merely being a webbing of understandings from which this metaphysics is constituted.

[This, to my mind, could get deep into epistemological issues of justification: which, as per the above, I currently perceive to involve some variation of foundherentism. This being a crossbreed of foundationalism (in conforming to the laws of thought and to physicality, if not also to some aspects of experience) and coherentism (in relation to a particular metaphysics' ideal lack of self-contradiction in the understandings it holds). Likely a different issue, though.]

At any rate, this is only a rough sketch of a general idea. Still, while its likely incomplete, I nevertheless so far find it to, well … to hold a fair share of explanatory power—this in terms of the different types of modalities addressed in this thread.

Elaborate on what?

"Infinite person" is a contradiction. Person already refers to one, while infinite refers to more than one.

The leading example I've seen of a posteriori necessity is that of "Venus = Lucifer". I so far find this fishy. Any bloke on the street will tell you that "Venus" does not equal "Lucifer". That they both in part reference the same physical planet is not the whole of the story.

Then again, who knows, maybe love does equal lucidity after all. :grin:

"Infinite person" is one person that is infinite in extent, not "more than one" person. The concept is no more contradiction in logic than "pegasus" or "chocolate fudge mountain".

"Infinite person" is one person that is infinite in extent, — 180 Proof

Try it this way: "infinite" in all cases means "not finite", where "finite" means "having an end or limit". A person in all cases is finite in both mind and body. Hence, "infinite person" is contradictory.

Yes, metaphysiically, not logically.

Yes, metaphysiically, not logically. — 180 Proof

How do you figure not logically? To rephrase: an infinite person is at the same time and in the same sense both a) a person that does not have end or limit to mind and body (this on account of being infinite) and b) a person that does have end or limit to mind and body (this on account of being a person). This is a logical contradiction: A and not-A at the same time and in the same respect.

Without warrant you ascribe the property of being "finite" to "person" which is not intrinsic to the concept. Also, circles (or spheres) are both infinite and finite simultaneously ...

Is conceptual possibility the same thing as metaphysical possibility?

Without warrant ou ascribe the property of being "finite" to "person" which is not intrinsic to the concept. — 180 Proof

Please justify this so far unsupported affirmation to someone who can't comprehend it. Is any person, for one example, omnipresent bodily or omniscient mentally?

Also, circles (or spheres) are both infinite and finite simultaneously ... — 180 Proof

Sure, but in different respects. Hence, they are not logically contradictory.

@180 Proof is right in a way. When formalised, "an infinite person" does not entail a contradiction. There is an X that is both i and p. No problem logically.

However if we think of the concept of a person, and then the concept of infinity, can they both be properties of the same subject? Well, inevitably it depends on what our concepts are. If we start with a concept of a person as a a thing with spatial limits, and infinity as without spatial limits, then an infinite person would be a conceptual impossibility. Is this what is meant by metaphysical possibility?

The leading example I've seen of a posteriori necessity is that of "Venus = Lucifer". I so far find this fishy. Any bloke on the street will tell you that "Venus" does not equal "Lucifer". That they both in part reference the same physical planet is not the whole of the story. — javra

The sense/reference distinction. By sense it’s metaphysically possible that they’re different but by reference it’s metaphysically necessary that they’re the same.

180 Proof is right in a way. When formalised, "an infinite person" does not entail a contradiction. There is an X that is both i and p. No problem logically.

However if we think of the concept of a person, and then the concept of infinity, can they both be properties of the same subject? Well, inevitably it depends on what our concepts are. If we start with a concept of a person as a a thing with spatial limits, and infinity as without spatial limits, then an infinite person would be a conceptual impossibility. Is this what is meant by metaphysical possibility? — bert1

The issue is what that X innately entails. Here, X = person. That X is both A (infinite) and not-A (finite) at the same time and in the same respect will be what the very definition of what a logical contradiction is.

The only conceivable exception I can think of would be that of the Trinity consisting of the Father, the Son, and the Holly Ghost as three different persons in one omni-this-and-that-being. Some of us strongly deem this to be logically contradictory (even if some subset of such might revere Jesus Christ's being/character/etc):

Jesus Christ's body was limited to a human body, as all accounts of him attest to, for example. Jesus Christ's mind was limited to, for example, what he as a subject of awareness perceived - rather than him perceiving what all subjects of awareness perceive in a simultaneously manner, for example - this, again, as all accounts of him attest to.

The Father in Genesis II onward was limited to his walking the garden of Eden, hence was bodily limited. He was also limited in in his forethought of what the serpent, Eve, and Adam would choose to do, hence was not omniscient.

As to the holy ghost being a person, I challenge anyone to cogently explain what this could possibly mean.

All that aside, a person is commonly understood to be a human being, no?

The sense/reference distinction. By sense it’s metaphysically possible that they’re different but by reference it’s metaphysically necessary that they’re the same. — Michael

Can you clarify the attempted distinction. Venus references love as well as a planet X. Lucifer references lucidity as well as the same planet X. The sense of each term is then obtained from the totality of what each term references - or so it so far seems to me.

It currently feels like materialism is creeping in: as though only physical referents can be deemed the actual referents of terms. This in contrast to senses being immaterial, which, in then possibly referencing immaterial attributes (such as that of love or of lucidity), aren't deemed to reference any actual givens.

Can you clarify the attempted distinction. Venus references love as well as a planet X. Lucifer references lucidity as well as the same planet X. The sense of each term is then obtained from the totality of what each term references - or so it so far seems to me. — javra

In the context of this discussion the terms refer to an object in the solar system.

In the context of this discussion the terms refer to an object in the solar system. — Michael

I get that, but then how does one obtain the necessity of equivalency between terms when they each in large part specify different things, such as in different contexts?

Rephrased, that a rose by any other name would smell as sweet speaks to the necessity of the physical item's identity being unitary irrespective of how it might be termed and, hence, referenced - but not to the necessarily equivalency of terms that can be used to address said item.

Back to a posteriori necessity, then, it is not necessary (logically, metaphysically, or physically) that the term "Venus" equates to the term "Lucifer". It is only necessary that were each separate term (each laden with its own many connotations and denotations) to happen to be used to address the same physical referent, that then and only then both terms be usable as means of referencing the same physical given. But that's a tautology: if it is true that both X and Y can be used to reference Z, then it is true that X and Y are interchangeable - and in this sense alone equivalent - only in so far as both can be used to reference Z. This tautology doesn't seem to me to then support any a posteriori necessity.

What am I not comprehending here?

If it's logically possible, it is metaphysically possible too. I don't believe we could postulate something logically which could, in principle, be impossible metaphysically, unless one wants to play word games like golden-lead, or a triangular circle.

The term “morning star” was used to refer to an object in space that appeared in the morning. The term “evening star” was used to refer to an object in space that appeared in the evening. Given that the object in space that appeared in the morning is the same object in space that appeared in the evening, and given that an object is necessarily itself, it then follows that the morning star is necessarily the evening star, even though this cannot be known a priori. Hence it being an a posteriori necessity.

But as I said, I think this is only the case if we consider the meaning of “morning star” and “evening star” in terms of their referent(s). I don’t think this is the case if we consider the meaning of “morning star” and “evening star” in terms of their senses.

But as I said, I think this is only the case if we consider the meaning of “morning star” and “evening star” in terms of their [physical] referent(s). I don’t think this is the case if we consider the meaning of “morning star” and “evening star” in terms of their sense(s). — Michael

While I still find the notion of a posteriori necessity suspect for reasons aforementioned - for example, such as the issue of a term's sense(s) being precisely that which the term references - I do agree with what you here state.