If a person with access to the computer simulating whichever universe (or set of universes) a belief is about could in principle write a program that takes as input the current state of the universe (as represented in the computer) and outputs whether the belief is true, then the belief is meaningful.
(if the universe in question does not run on a computer, begin by digitizing your universe, then proceed as above)
That has the same problem as atomic-level specifications that become false when you discover QM. If the Church-Turing thesis is false, all statements you have specified thus become meaningless or false. Even using a hierarchy of oracles until you hit a sufficient one might not be enough if the universe is even more magical than that.
Taking you more strictly at your word than you mean it the program could just return true for the majority belief on empirically non-falsifiable questions. Or it could just return false on all beliefs including your belief that that is illogical. So with the right programs pretty much arbitrary beliefs pass as meaningful.
You actually want it to depend on the state of the universe in the right way, but that’s just another way to say it should depend on whether the belief is true.
That’s a problem with all theories of truth, though. “Elaine is a post-utopian author” is trivially true if you interpret “post-utopian” to mean “whatever professors say is post-utopian”, or “a thing that is always true of all authors” or “is made out of mass”.
To do this with programs rather than philosophy doesn’t make it any worse.
I’m suggesting is that there is a correspondence between meaningful statements and universal computer programs. Obviously this theory doesn’t tell you how to match the right statement to the right computer program. If you match the statement “snow is white” to the computer program that is a bunch of random characters, the program will return no result and you’ll conclude that “snow is white” is meaningless. But that’s just the same problem as the philosopher who refuses to accept any definition of “snow”, or who claims that snow is obviously black because “snow” means that liquid fossil fuel you drill for and then turn into gasoline.
If your closest match to “post-utopian” is a program that determines whether professors think someone is post-utopian, then you can either conclude that post-utopian literally means “something people call post-utopian”—which would probably be a weird and nonstandard word use the same way using “snow” to mean “oil” would be nonstandard—or that post-utopianism isn’t meaningful.
Yeah, probably all theories of truth are circular and the concept is simply non-tabooable. I agree your explanation doesn’t make it worse, but it doesn’t make it better either.
Doesn’t this commit you to the claim that at least some beliefs about whether or not a particular Turing machine halts must be meaningless? If they are all meaningful and your criterion of meaningfulness is correct, then your simulating computer solves the halting problem. But it seems implausible that beliefs about whether Turing machines halt are meaningless.
Suppose we are not living in a simulation. We are to digitize our universe. Do we make our digitization include stars outside the cosmological horizon? By what principle do we decide?
(I suppose you could be asking us to actually digitize the universe, but we want a principle we can use today.)
Well, if the universe actually runs on a computer, then presumably that computer includes data for all stars, not just the ones that are visible to us.
If the universe doesn’t run on a computer, then you have to actually digitize the universe so that your model is identical to the real universe as if it were on a computer, not stop halfway when it gets too hard or physically impossible.
I don’t think any of these principles will actually be practical. Even the sense-experience principle isn’t useful. It would classify “a particle accelerator the size of the Milky Way would generate evidence of photinos” as meaningful, but no one is going to build a particle accelerator the size of the Milky Way any more than they are going to digitize the universe. The goal is to have a philosophical tool, not a practical plan of action.
Oh, I didn’t express myself clearly in the last paragraph of the grandparent. Don’t worry, I’m not trying to demand any kind of practical procedure. I think we’re on the same page. However:
Well, if the universe actually runs on a computer, then presumably that computer includes data for all stars, not just the ones that are visible to us.
I don’t think we can really say that in general. Perhaps if the computer stored the locations and properties of stars in an easy-to-understand way, like a huge array of floating-point numbers, and we looked into the computer’s memory and found a whole other universe’s worth of extra stars, with spatial coordinates that prevent us from ever interacting with them, then we would be comfortable saying that those stars exist but are invisible to us.
But what if the computer compresses star location data, so the database of visible stars looks like random bits? And then we find an extra file in the computer, which is never accessed, and which is filled with random bits? Do we interpret those as invisible stars? I claim that there is no principled, objective way of pointing to parts of a computer’s memory and saying “these bits represent stars invisible to the simulation’s inhabitants, those do not”.
If the universe doesn’t run on a computer, then you have to actually digitize the universe so that your model is identical to the real universe as if it were on a computer [...]
I’m suspicious of the phrase “identical to the real universe as if it were on a computer”. It seems like a black box. Suppose we commission a digital model of this universe, and the engineer in charge capriciously programs the computer to delete information about any object that passes over the cosmological horizon. But they conscientiously program the computer to periodically archive snapshots of the state of the simulation. It might look like this model does not contain spaceships that have passed over the cosmological horizon. But the engineer points out that you can easily extrapolate the correct location of the spaceship from the archived snapshots — the initial state and the laws of physics uniquely determine the present location of the spaceship beyond the cosmological horizon, if it exists. The engineer claims that the simulation actually does contain the spaceship outside the cosmological horizon, and the extrapolation process they just described is simply the decompression algorithm. Is the engineer right? Again, we run into the same problem. To answer the question we must either make an arbitrary decision or give an answer that is relative to some of the simulation’s inhabitants.
And now we have the same problem with deciding whether this digital model is “identical to the real universe as if it were on a computer”. Even if we believe that the spaceship still exists, we have trouble deciding whether the spaceship exists “in the model”.
Well, if the universe actually runs on a computer, then presumably that computer includes data for all stars, not just the ones that are visible to us.
Why should it if its purpose is to simulate reality for humans? What’s wrong with a version of The Truman Show?
Because since everything would be a simulation, “all stars” would be identical in meaning with “all stars that are being simulated” and with “all stars for which the computer includes data”.
In a Truman Show situation, the simulators would’ve shown us white pin-pricks for thousands of years, and then started doing actual astrophysics simulations only when we got telescopes.
If a person with access to the computer simulating whichever universe (or set of universes) a belief is about could in principle write a program that takes as input the current state of the universe (as represented in the computer) and outputs whether the belief is true, then the belief is meaningful.
(if the universe in question does not run on a computer, begin by digitizing your universe, then proceed as above)
That has the same problem as atomic-level specifications that become false when you discover QM. If the Church-Turing thesis is false, all statements you have specified thus become meaningless or false. Even using a hierarchy of oracles until you hit a sufficient one might not be enough if the universe is even more magical than that.
But that’s only useful if you make it circular.
Taking you more strictly at your word than you mean it the program could just return true for the majority belief on empirically non-falsifiable questions. Or it could just return false on all beliefs including your belief that that is illogical. So with the right programs pretty much arbitrary beliefs pass as meaningful.
You actually want it to depend on the state of the universe in the right way, but that’s just another way to say it should depend on whether the belief is true.
That’s a problem with all theories of truth, though. “Elaine is a post-utopian author” is trivially true if you interpret “post-utopian” to mean “whatever professors say is post-utopian”, or “a thing that is always true of all authors” or “is made out of mass”.
To do this with programs rather than philosophy doesn’t make it any worse.
I’m suggesting is that there is a correspondence between meaningful statements and universal computer programs. Obviously this theory doesn’t tell you how to match the right statement to the right computer program. If you match the statement “snow is white” to the computer program that is a bunch of random characters, the program will return no result and you’ll conclude that “snow is white” is meaningless. But that’s just the same problem as the philosopher who refuses to accept any definition of “snow”, or who claims that snow is obviously black because “snow” means that liquid fossil fuel you drill for and then turn into gasoline.
If your closest match to “post-utopian” is a program that determines whether professors think someone is post-utopian, then you can either conclude that post-utopian literally means “something people call post-utopian”—which would probably be a weird and nonstandard word use the same way using “snow” to mean “oil” would be nonstandard—or that post-utopianism isn’t meaningful.
Yeah, probably all theories of truth are circular and the concept is simply non-tabooable. I agree your explanation doesn’t make it worse, but it doesn’t make it better either.
Doesn’t this commit you to the claim that at least some beliefs about whether or not a particular Turing machine halts must be meaningless? If they are all meaningful and your criterion of meaningfulness is correct, then your simulating computer solves the halting problem. But it seems implausible that beliefs about whether Turing machines halt are meaningless.
Input->Black box->Desired output. “Black box” could be replaced with”magic.” How would your black box work in practice?
That doesn’t help us decide whether there are stars outside the cosmological horizon.
I feel like writing a more intelligent reply than “Yes it does”, so could you explain this further?
Suppose we are not living in a simulation. We are to digitize our universe. Do we make our digitization include stars outside the cosmological horizon? By what principle do we decide?
(I suppose you could be asking us to actually digitize the universe, but we want a principle we can use today.)
Well, if the universe actually runs on a computer, then presumably that computer includes data for all stars, not just the ones that are visible to us.
If the universe doesn’t run on a computer, then you have to actually digitize the universe so that your model is identical to the real universe as if it were on a computer, not stop halfway when it gets too hard or physically impossible.
I don’t think any of these principles will actually be practical. Even the sense-experience principle isn’t useful. It would classify “a particle accelerator the size of the Milky Way would generate evidence of photinos” as meaningful, but no one is going to build a particle accelerator the size of the Milky Way any more than they are going to digitize the universe. The goal is to have a philosophical tool, not a practical plan of action.
Oh, I didn’t express myself clearly in the last paragraph of the grandparent. Don’t worry, I’m not trying to demand any kind of practical procedure. I think we’re on the same page. However:
I don’t think we can really say that in general. Perhaps if the computer stored the locations and properties of stars in an easy-to-understand way, like a huge array of floating-point numbers, and we looked into the computer’s memory and found a whole other universe’s worth of extra stars, with spatial coordinates that prevent us from ever interacting with them, then we would be comfortable saying that those stars exist but are invisible to us.
But what if the computer compresses star location data, so the database of visible stars looks like random bits? And then we find an extra file in the computer, which is never accessed, and which is filled with random bits? Do we interpret those as invisible stars? I claim that there is no principled, objective way of pointing to parts of a computer’s memory and saying “these bits represent stars invisible to the simulation’s inhabitants, those do not”.
I’m suspicious of the phrase “identical to the real universe as if it were on a computer”. It seems like a black box. Suppose we commission a digital model of this universe, and the engineer in charge capriciously programs the computer to delete information about any object that passes over the cosmological horizon. But they conscientiously program the computer to periodically archive snapshots of the state of the simulation. It might look like this model does not contain spaceships that have passed over the cosmological horizon. But the engineer points out that you can easily extrapolate the correct location of the spaceship from the archived snapshots — the initial state and the laws of physics uniquely determine the present location of the spaceship beyond the cosmological horizon, if it exists. The engineer claims that the simulation actually does contain the spaceship outside the cosmological horizon, and the extrapolation process they just described is simply the decompression algorithm. Is the engineer right? Again, we run into the same problem. To answer the question we must either make an arbitrary decision or give an answer that is relative to some of the simulation’s inhabitants.
And now we have the same problem with deciding whether this digital model is “identical to the real universe as if it were on a computer”. Even if we believe that the spaceship still exists, we have trouble deciding whether the spaceship exists “in the model”.
Why should it if its purpose is to simulate reality for humans? What’s wrong with a version of The Truman Show?
Because since everything would be a simulation, “all stars” would be identical in meaning with “all stars that are being simulated” and with “all stars for which the computer includes data”.
In a Truman Show situation, the simulators would’ve shown us white pin-pricks for thousands of years, and then started doing actual astrophysics simulations only when we got telescopes.
A variant of Löb’s theorem, isn’t it?
Edit: Downvoted because the parallels are too obvious, or because the comparison seems too contrived? “E”nquiring minds want to know …