Does conceivability imply possibility?

[Theftz22]

While modal logic may be highly useful, I don't think the notion of conceivability implying possibility is useful at all. It's like solipsism, it doesn't really go anywhere.

Well if you agree that modal logic is important, then, by extension, you agree that, at least if true, conceivability implying possibility is important, since whether or not some things are logically possible you've already conceded is important. Like it would be important if conceivability entails possibility because you can conceive of god not existing. But then it follows that possibly god does not exist. But then by axiom S5 of modal logic, god actually does not exist. And similarly to conceive of the mind existing without the brain would show that the mind is actually not identical to the brain.

Well... That's the point. There may be possible universes that are incoherent to us with all the laws of logic and math changed. And if this is the case, then anything is possible, if you pick the right universe. I'm just pointing out that if this is the case, the debate is moot as everything is possible.

Logical contradictions don't exist in any possible world. They are logically impossible. I don't see how there could be a possible world with different laws of logic and math.

 

[Bob Jane T-Mart]

Well if you agree that modal logic is important, then, by extension, you agree that, at least if true, conceivability implying possibility is important, since whether or not some things are logically possible you've already conceded is important. Like it would be important if conceivability entails possibility because you can conceive of god not existing. But then it follows that possibly god does not exist. But then by axiom S5 of modal logic, god actually does not exist. And similarly to conceive of the mind existing without the brain would show that the mind is actually not identical to the brain.

To be honest this seems like a very shoddy line of reasoning. If you can conceive of the mind existing without the brain, then the brain is not identical to the mind? But here's the problem does that actually mean anything? Let's say that you can conceive of minds existing without brain. You've also shown that the mind is somehow not identical to the brain. But what if your answer is contradicted by science? And if the mind is somehow not identical to the brain, then what does that mean?

And if you've proven that dualism is logically possible. But whether it actually exists is a different matter. Whether it's physically possible is a different matter as well.

Logical contradictions don't exist in any possible world. They are logically impossible. I don't see how there could be a possible world with different laws of logic and math.

No but the point is that the laws of logic and math may be different in different universes. We don't know. Just because you can't see how it's possible, doesn't mean it's impossible. That my friend is an argument from incredulity. I'll bet you can't see how a 4th dimension of space would work. How about a 5th? 6th? etc. Just because you can't comprehend something, it doesn't mean it's impossible.

 

[Theftz22]

To be honest this seems like a very shoddy line of reasoning. If you can conceive of the mind existing without the brain, then the brain is not identical to the mind? But here's the problem does that actually mean anything? Let's say that you can conceive of minds existing without brain. You've also shown that the mind is somehow not identical to the brain. But what if your answer is contradicted by science? And if the mind is somehow not identical to the brain, then what does that mean?

Yes, it means that the mind has different modal properties than the brain in the actual world, which means that they are not the same thing. So you are forced to either property or substance dualism. I don't see how it could contradict science since science can't prove that the mind is identical to the brain. It can causally reduce the mind to the brain, but it can't ontologically reduce the mind to the brain.

And if you've proven that dualism is logically possible. But whether it actually exists is a different matter. Whether it's physically possible is a different matter as well.

Well no, in this case some form of dualism being logically possible would entail its actual truth, so long as by dualism we mean the thesis that the mind is not the same thing as the brain.

No but the point is that the laws of logic and math may be different in different universes. We don't know. Just because you can't see how it's possible, doesn't mean it's impossible. That my friend is an argument from incredulity. I'll bet you can't see how a 4th dimension of space would work. How about a 5th? 6th? etc. Just because you can't comprehend something, it doesn't mean it's impossible.

But the thing is that while I might not be able to understand how more dimensions of space would work, claiming that there are more dimensions of space isn't flatly contradictory. Given what I mean by things like 2, +, and 5 I just don't even understand what you're saying if you say that 2+2=5. Similarly, I just don't understand what you even mean by "bachelor" and "married" if you say that there is a possible world with a married bachelor. At least we can articulate a coherent proposition about more dimensions of space.

 

[Bob Jane T-Mart]

Yes, it means that the mind has different modal properties than the brain in the actual world, which means that they are not the same thing. So you are forced to either property or substance dualism. I don't see how it could contradict science since science can't prove that the mind is identical to the brain. It can causally reduce the mind to the brain, but it can't ontologically reduce the mind to the brain.

Well, I'm sure that science can reduce the mind to the brain. You affect one, you affect the other, they act as if they are one entity. Science says that they're for all intents and purposes, one and the same.

Well no, in this case some form of dualism being logically possible would entail its actual truth, so long as by dualism we mean the thesis that the mind is not the same thing as the brain.

So we end up with a tautology?

But the thing is that while I might not be able to understand how more dimensions of space would work, claiming that there are more dimensions of space isn't flatly contradictory. Given what I mean by things like 2, +, and 5 I just don't even understand what you're saying if you say that 2+2=5. Similarly, I just don't understand what you even mean by "bachelor" and "married" if you say that there is a possible world with a married bachelor. At least we can articulate a coherent proposition about more dimensions of space.

Well, that's simply because your or my brain isn't able to comprehend these ideas. We're not wired to live in a universe where the laws of logic and math are different.

 

[Theftz22]

Well, I'm sure that science can reduce the mind to the brain. You affect one, you affect the other, they act as if they are one entity. Science says that they're for all intents and purposes, one and the same.

Of course the effects on the brain affect the mind, no dualism which hopes to be tenable denies this. But a direct causal relationship is obviously not the same thing as an identity relationship. Fire has a direct causal relationship with smoke, but fire is not identical to smoke. Science may be able to establish a direct causal relationship between the brain and mind, but not an identity one.

So we end up with a tautology?

No what we end up with if conceivability entails possibility is this:

1. The mind existing without the brain is conceivable.
2. Therefore the mind existing without the mind is possible.
3. Therefore the mind is possibly not identical to the brain.
4. Therefore the mind is actually not identical to the brain.
5. Therefore some kind of dualism is true.

That's not a tautology.

Well, that's simply because your or my brain isn't able to comprehend these ideas. We're not wired to live in a universe where the laws of logic and math are different.

It's not just that we can't comprehend them it's that they're flatly contradictory.

 

[AltF4]

i think it's clear that by the new standard for conceivability we've set up here, premise 1 doesn't come close to holding.

 

[Theftz22]

I disagree. I've already argued that depictability entails conceivability. And the mind existing without the brain is depictable. There are many movies that do exactly that.

 

[AltF4]

The ability to make a movie about it is not sufficient for the standard that we've set up for conceivability earlier in the thread. You have to be able to account for every slightest detail of inner workings in order for it to be conceivable. Otherwise you're just imaging the idea of the thing. Any one of these inner workings could be logically impossible (and you just haven't discovered it yet). Until you've accounted for every single detail, you haven't properly conceived of the thing. Only part of the thing. All the details matter, you can't glaze over them.

In order to say that you can conceive of minds separate from bodies, you have to definitively solve the mind-body problem. You have to reconcile this with physics. You have to tell me definitively and with provable certainty the answer to all sorts of questions that you don't know the answer to. Such as: Would an atom for atom clone of an individual share the same mind?

Sure, you could speculate. But if you knew every inner working of the how the mind worked, then you could definitively provide the truthful answer. But you can't.


Which is why this definition for conceivability is stupid. It's clearly not what's meant by the common use of the word. And it's also clearly designed to be equivalent to possibility. Which is stupid when the whole point is to show that one implies the other. Redefining one word to be equal to the other doesn't solve anything.

 

[Theftz22]

I'm not sure where you got the idea that you need to be able to conceive of exactly how the thing in question works to be able to conceive of it. I certainly never said such a thing. Maybe Dre did. But I'm perfectly fine with saying that something is conceivable iff you can form a mental image of it. That mental image would need to include all of its features, but not how it all worked.

Actually I think a more reliable move can be straight from depictability to possibility. It occurs to me that the talk of conceivability is probably unecessary.

 

[Budget Player Cadet_]

I'm not sure where you got the idea that you need to be able to conceive of exactly how the thing in question works to be able to conceive of it. I certainly never said such a thing. Maybe Dre did. But I'm perfectly fine with saying that something is conceivable iff you can form a mental image of it. That mental image would need to include all of its features, but not how it all worked.

Actually I think a more reliable move can be straight from depictability to possibility. It occurs to me that the talk of conceivability is probably unecessary.

...But we can imagine a Zeno machine. As AltF4 pointed out, we can create a complete blueprint for it, with each of the parts figured out; we just cannot build it for various reasons. It is entirely depictable. But the problem with that is, that the Zeno machine is simply logically impossible, and therefore a clear disproof of the concept at hand here.

 

[AltF4]

Also consider the Grandfather Paradox. You can depict time traveling to your own past, and you can picture having free will. You can picture having them together. But it's a logical impossibility. It leads to the grandfather paradox.

If you could time travel into your own past AND had free will to do what you wanted there, then you could kill your own grandfather. So that means you wouldn't be born. Which means you don't go back in time to kill your grandfather. Which means that you will be born. It's a contradiction.

But there's countless movies about this sort of thing. Clearly depictability does not imply possibility.


Why you should not be surprised to learn depictability/conceivability do not imply possibility:

-To say that something is depictable is a statement not about the thing, but rather of the state of the human brain. It says that our primitively evolved, mammalian, frequently wrong brains have come to some conclusion. That our brains have been able to produce a mental image of some or part of a thing.

-To say that something is possible is a statement about facts of the universe.


While there is certainly a correlation between depictability and possibility, one does not imply the other in all cases.

 

[blazedaces]

Why is this discussion/argument still going on? It's going in circles.

-blazed