Philosophy Discussion Forums | A Humans-Only Philosophy Club

[Bahman]

What is nomologically possible is logically possible, and what is logically impossible is nomologically impossible.

No that is not so. It might be so, but there is a reason we might use nomological or logical adjectivally.
Logic is not about the laws of nature, though it might be.

If the laws of nature are all physical laws, then nomological modality = physical modality. Logic isn't physics, but logical impossibility entails physical impossibility, and physical possibility entails logical possibility.

Could you please elaborate on this?

[GrayArea]

Self-causation is possible for self-causation itself.

Circular arguments are circular and are meaningless.

Not when it comes to describing the circle itself.

Not even then.
A circle is a circle is a circle.
Not very impressive.

It's fine if you don't get it.

[Sculptor1]

Circular arguments are circular and are meaningless.

Not when it comes to describing the circle itself.

Not even then.
A circle is a circle is a circle.
Not very impressive.

It's fine if you don't get it.

It might be alright for you.
But I get it.

[Sculptor1]

"Self-causation is possible for self-causation itself."

hilarious tautology.

[Gertie]

To show this we first notice that any act including the act of creation has a before and an after. This means that time is needed for any act since there is a before and an after in any act. The act of creation however includes the creation of time as well. This means that we need time for the creation of time. This leads to an infinite regress. The infinite regress is not acceptable. Therefore, the act of creation from nothing is logically impossible.

It's a weird question to try to get your head round, for me anyway. But here's how I see it.

I understand time to be a marker of change. Without change, time is meaningless.

I know change exists because my conscious experience changes.  I assume the change in my conscious experience represents the sequentially changing universe my experience represents. (Time being relative doesn't mean it doesn't exist as marking change, just that how we experience and measure it is relative, I think).

And I understand logic to be a human concept which is rooted in our observation and understanding of how our universe works.


Now within our already existing universe as we experience and understand it, to say time/change/anything is created out of nothing/no time/no change at a particular  temporal moment seems illogical.  Because we live in a pre-existing universe and only understand time as marking the change from one state of affairs to another, which we experience and have coherent and reliably predictive ways of explaining.

However, if we're talking about the creation of our universe, we're considering a different state of affairs we call 'nothing' (aka not our universe) and we have no access  to  how things work 'outside' or 'before' our universe.  If or how time, stuff changing, or logic can make sense to us outside what we can access from within our universe.  So for example if we're considering the existence of some creative force which is responsible for the existence of our universe (including time, stuff and logic as we experience/understand it), we have no way of knowing what the conditions in which such an act of creation might or might not occur.  That's assuming the notion of 'outside our universe', or outside what is epistemologically accessible to us, is itself meaningful.

We can speculate, but using our 'in-universe' notions of logic based on how our universe seems to work to do so,  could well be simply not understanding the implications of trying to say anything about what is outside what we can know or understand.  Or if it even makes sense to try.


On the other hand if we consider our universe to be eternal/infinite having no temporal beginning, we run into apparent paradoxes, in which our logic seems incapable of reconciling our universe's infinite past with reaching this point now, and now, and now, like Xeno's arrow. Or how our spatially infinite universe which encompasses everything can expand.


As flawed and limited observers and thinkers whose ways of understanding our universe and how things work is molded and  limited  by our in-universe experience of it, it looks like an impasse we don't have the toolkit to explain.

In such circs - dunno is the appropriate answer. 

[GE Morton]

On the other hand if we consider our universe to be eternal/infinite having no temporal beginning, we run into apparent paradoxes, in which our logic seems incapable of reconciling our universe's infinite past with reaching this point now, and now, and now, like Xeno's arrow. Or how our spatially infinite universe which encompasses everything can expand.

An eternal universe entails no paradoxes. Xeno's paradoxes of motion involve traversing an infinite number of points in a finite time. But there is no problem with traversing an infinite number of points in infinite time, and infinite time is what the eternal universe assumes).

Also, according to Einstein, the (observable) universe is not infinite, but "finite, but unbounded." Now, according to the many worlds interpretation of QM, there many other universes, perhaps infinitely many. But there seems to be no way to test that hypothesis.

[Consul]

If the laws of nature are all physical laws, then nomological modality = physical modality. Logic isn't physics, but logical impossibility entails physical impossibility, and physical possibility entails logical possibility.

Could you please elaborate on this?

There are formal relations between the different kinds of modality. See:

https://plato.stanford.edu/entries/moda ... rgEpisModa

[Consul]

Source of the figure: https://plato.stanford.edu/entries/moda ... stemology/

QUOTE>
"We can distinguish physical possibility and necessity, from metaphysical possibility and necessity, and both from logical possibility and necessity. Alternate physically possible worlds need to be the same as the actual world in terms of their natural structure. They must have the same natural laws. Metaphysically possible worlds include worlds that are physically impossible given actual natural laws. Much more is metaphysically possible than is physically possible. The only limit on metaphysical possibilities is that everything must have its essence in every metaphysically possible world. Logical possibility is the broadest category of possible worlds. The only limit on logical possibility is logical consistency.
We can think of the sets of physically, metaphysically, and logically possible worlds as nested in concentric circles. The innermost circle includes just the physically possible worlds, then the next circle includes the metaphysically possible worlds as well. The most inclusive circle is the logically possible worlds.
It is physically possible for me to have lived in San Francisco. This violates no natural laws. It is also metaphysically possible and logically possible.
It is metaphysically possible for me to swim across the Atlantic Ocean, but it is not physically possible. It is also logically possible.
It is logically possible for me to be an alligator (no logical contradiction), but it is not metaphysically possible (assuming that I am essentially human), and it is certainly not physically possible."

(Schwartz, Stephen P. A Brief History of Analytic Philosophy: From Russell to Rawls. Malden, MA: Wiley-Blackwell, 2012. pp. 262-3)
<QUOTE

[Gertie]

On the other hand if we consider our universe to be eternal/infinite having no temporal beginning, we run into apparent paradoxes, in which our logic seems incapable of reconciling our universe's infinite past with reaching this point now, and now, and now, like Xeno's arrow. Or how our spatially infinite universe which encompasses everything can expand.

An eternal universe entails no paradoxes. Xeno's paradoxes of motion involve traversing an infinite number of points in a finite time. But there is no problem with traversing an infinite number of points in infinite time, and infinite time is what the eternal universe assumes).

Also, according to Einstein, the (observable) universe is not infinite, but "finite, but unbounded." Now, according to the many worlds interpretation of QM, there many other universes, perhaps infinitely many. But there seems to be no way to test that hypothesis.

I struggle with infinity, but re Xeno isn't the point that to move from point A to B, which can lie anywhere along a timeline, the distance can always be halved, an infinite number of times? Effectively creating never-endingly closer 'first' points. So if the closest point is never-endingly divisible, it might as well be never-endingly far away? In which case nothing can ever change its position and we're in a static universe.

(I don't believe we are in a static universe btw, the point is that our logic can't resolve such apparent paradoxes).

Re a 'bounded expanding universe', if you take Bahman's position that the universe must be infinite because a created universe isn't logical, then if we apply the notion of infinity to the size of the universe we hit a paradox too. If the universe is infinite, it is everything, and if it's everything (including space) there's nothing for it to expand into, but it seems to be expanding. This is more of a comment about the problems the idea of infinity brings once you start applying it to how we understand logic. Once you apply infinite characteristics to the universe, it seems you have to throw our in-universe notions of logic out the window. And to make claims about an infinite universe based on our 'in-universe' human ideas of logic and possibility, is a prob. I think.

[GE Morton]

Source of the figure: https://plato.stanford.edu/entries/moda ... stemology/

QUOTE>
"We can distinguish physical possibility and necessity, from metaphysical possibility and necessity, and both from logical possibility and necessity. Alternate physically possible worlds need to be the same as the actual world in terms of their natural structure. They must have the same natural laws. Metaphysically possible worlds include worlds that are physically impossible given actual natural laws. Much more is metaphysically possible than is physically possible. The only limit on metaphysical possibilities is that everything must have its essence in every metaphysically possible world. Logical possibility is the broadest category of possible worlds. The only limit on logical possibility is logical consistency.
We can think of the sets of physically, metaphysically, and logically possible worlds as nested in concentric circles. The innermost circle includes just the physically possible worlds, then the next circle includes the metaphysically possible worlds as well. The most inclusive circle is the logically possible worlds.
It is physically possible for me to have lived in San Francisco. This violates no natural laws. It is also metaphysically possible and logically possible.
It is metaphysically possible for me to swim across the Atlantic Ocean, but it is not physically possible. It is also logically possible.
It is logically possible for me to be an alligator (no logical contradiction), but it is not metaphysically possible (assuming that I am essentially human), and it is certainly not physically possible."

(Schwartz, Stephen P. A Brief History of Analytic Philosophy: From Russell to Rawls. Malden, MA: Wiley-Blackwell, 2012. pp. 262-3)
<QUOTE

"The only limit on metaphysical possibilities is that everything must have its essence in every metaphysically possible world."

Ah, those notorious "essences."

"It is logically possible for me to be an alligator (no logical contradiction), but it is not metaphysically possible (assuming that I am essentially human), and it is certainly not physically possible."

That is a logical impossibility in disguise. The definition of "human" differs from that of "alligator," and contradicts it in several respects (e.g., alligators have scales; I being human, don't). But perhaps having scales is not an "essential" property of reptiles. Whether it is or not just depends upon how we wish to define "reptile."

As used by many metaphysicians, anything is "metaphysically possible," including different rules of logic. That is a vacuous modal category that should be abandoned.

[GE Morton]

I struggle with infinity, but re Xeno isn't the point that to move from point A to B, which can lie anywhere along a timeline, the distance can always be halved, an infinite number of times? Effectively creating never-endingly closer 'first' points. So if the closest point is never-endingly divisible, it might as well be never-endingly far away? In which case nothing can ever change its position and we're in a static universe.

(I don't believe we are in a static universe btw, the point is that our logic can't resolve such apparent paradoxes).

Aristotle dealt with those paradoxes pretty well. He distinguished between "actual infinities" and "potential infinities." Actual infinities are those present in the external world; potential infinities are those that arise via our method of describing the world. E.g., the "points" on a line don't represent particles or any other physical or phenomena; they exist as concepts --- mental constructs --- only. A given point on a line is just a ratio of a portion of the line to its total length; not a physical "thing" or place. Physical motion is not constrained by such imaginary artifacts.

Re a 'bounded expanding universe', if you take Bahman's position that the universe must be infinite because a created universe isn't logical, then if we apply the notion of infinity to the size of the universe we hit a paradox too. If the universe is infinite, it is everything, and if it's everything (including space) there's nothing for it to expand into, but it seems to be expanding.

I agree that if "the universe" is construed to mean, "everything that exists or has ever existed," then its creation is not logical; for that would entail that something was created from nothing. Physicists, however, don't give that term so wide a scope; they consider it to be finite, with a size constrained by the speed of light (matter could only have traveled so far in the ~14 billion years since the Big Bang). If it is finite there is no problem with expansion --- it creates more space as it expands. It doesn't need space in which to expand --- it expands into nothingness (we can only speak of "space" when we have 2 or more separated entities).

[GE Morton]

If it is finite there is no problem with expansion --- it creates more space as it expands. It doesn't need space in which to expand --- it expands into nothingness (we can only speak of "space" when we have 2 or more separated entities).

According to the cyclic theory, the universe doesn't expand indefinitely; at some point the "dark energy" driving the expansion dissipates, and the universe begins to contract (the "Big Crunch"). When its density is high enough we get another Big Bang. The cycle repeats eternally.

https://en.wikipedia.org/wiki/Cyclic_model

https://en.wikipedia.org/wiki/Dark_energy

[Consul]

"The only limit on metaphysical possibilities is that everything must have its essence in every metaphysically possible world."

Ah, those notorious "essences."

"It is logically possible for me to be an alligator (no logical contradiction), but it is not metaphysically possible (assuming that I am essentially human), and it is certainly not physically possible."

That is a logical impossibility in disguise. The definition of "human" differs from that of "alligator," and contradicts it in several respects (e.g., alligators have scales; I being human, don't). But perhaps having scales is not an "essential" property of reptiles. Whether it is or not just depends upon how we wish to define "reptile."

As used by many metaphysicians, anything is "metaphysically possible," including different rules of logic. That is a vacuous modal category that should be abandoned.

"The core idea is that metaphysical modality is not restricted by the laws of nature and is more substantive than logical-conceptual modality. As such, it is plausibly the modality of philosophical thinking par excellence." (https://plato.stanford.edu/entries/moda ... stemology/)

It is a very contentious issue whether there is such a distinctive kind of modality that is stronger than nomological/physical modality and weaker than logical (logico-conceptual) modality. The core idea is intuitively plausible to me, but a precise definition is hard to come by. Nonetheless, the essentialist approach to metaphysical modality (as developed and defended by Kit Fine and others) isn't vacuous. According to it, what is metaphysically necessary/possible/impossible is determined by what is and what isn't compatible with a thing's essence or nature (= the set or sum of its essential properties).

For example, if I am essentially a member of the species homo sapiens, then it is metaphysically impossible for me to be or become a member of a species of alligators. It would also be logically impossible for me if my actually being an alligator entailed a logical contradiction. Does it? If yes, what contradiction does it entail?

By the way, I use "metaphysical modality" and "ontological modality" synonymously.

[Consul]

For example, if I am essentially a member of the species homo sapiens, then it is metaphysically impossible for me to be or become a member of a species of alligators. It would also be logically impossible for me if my actually being an alligator entailed a logical contradiction. Does it? If yes, what contradiction does it entail?

Of course, being a human alligator does entail logical contradictions. For example, humans have sex chromosomes and alligators don't; so if I were a human alligator, I would both have and lack sex chromosomes, which is a logically contradictory state of affairs. However, that my being a human alligator is logically impossible doesn't mean that my being an alligator is logically impossible too.

[Consul]

…According to [the essentialist approach to metaphysical modality], what is metaphysically necessary/possible/impossible is determined by what is and what isn't compatible with a thing's essence or nature (= the set or sum of its essential properties).

"[W]e have an informal way of saying that an object essentially has a certain property. We say 'the object must have that property if it is to be the object that it is'. Somehow this form of words manages to convey what we wish to convey."

(Fine, Kit. "Essence and Modality: The Second Philosophical Perspectives Lecture." Philosophical Perspectives 8 (1994): 1–16. p. 4)

If nothing has an essence, then everything could be/have been anything—and that just isn't plausible.