What would constitute proof of a ghost?

[JoeTheJuggler]

It's easy to define a 4 sided triangle. It is a triangle with four sides

I know. Now how do you answer the question, "What would constitute proof of a 4-sided triangle?" It's not at all difficult to state a contradiction: a thing with the inherent characteristics of visible and invisible, dead and not-dead, material and immaterial, and so on. The problem isn't making a contradiction. The problem is that things whose definitions include a contradiction are impossible. . . like a four sided triangle.

I think we can come up with a definition of what a ghost is; or rather we can have a number of different definitions for them. We have things shaped like people who appear and repeat the same actions again and again; we have things that have no form and hurl things around; we have things that clank chains and promise you eternal damnation unless you repent of your ways, and so on and so on. These are what are commonly called "ghosts". Why is that not enough to work on?

As a logical definition, it's incomplete because it doesn't exclude living humans (and probably a number of other things that are not ghosts). As an operational definition, it doesn't come close because it doesn't tell us what we need to measure to determine if a thing is a "ghost".

Take one of those: Poltergeists. They don't have a visible physical form, but they chuck things around. Why is that not a useful working definition of a ghost? You seem to be asserting that it is not useful simply because by normal expectations things that are invisible are unable to chuck things around therefore poltergeists do not exist QED. It may not be a very robust definition and what is doing the chucking may not actually be a ghost - but then isn't that what the OP was asking? What would be incontrovertible proof of a ghost? Maybe invisible things that chuck things around wouldn't be - so then what would?

Again, it's not complete. The wind is invisible and it can "chuck things around", yet it's not a poltergeist.

I simply think you are requiring too rigorous a definition. I don't think the OP was asking for a formal proof of ghosts, just asking what criteria something would have to provide in order to be deemed a certain ghost.

And you can't find such "certain" evidence without rigorously defining the term. The ambiguity in the OP's question has already been noted. I agree that Nursedan was probably not asking about deductive logical proof (which would require a formal logical definition), but rather about inductive proof, which requires an operational definition that would tell us what we'd need to measure/observe.

If you have an operational definition, then the answer to the OP's question would be plain and obvious.

I think the biggest problem with the operational definitions that have been offered so far is that they bear little resemblance to conventional usage of the term ghost. (Also, no one has actually formalized their attempt at an operational definition. It should say exactly what we have to measure or observe to know if something is a ghost. If they did that, then the OP's question would be answered.)

 

[Crossbow]

This is a spinoff of another thread concerning a picture of a "ghost". I realized that while no one responding in that thread really believed that a ghost had been seen, the responses centered around how the picture was probably faked. It got me thinking, what is proof of a ghost? What do people who believe in ghosts point to as proof? Pictures? Is that really enough? It's either a picture of "something" they saw or anecdotal evidence.

If ghosts exist, how would one prove it? Since we know pictures and fables aren't cutting it.

If my premise isn't clear enough, I can elaborate.

Just in case anyone is still interested, I had a bit of discussion with 'JoeTheJuggler' about the issue of proof for ghosts and I said that I would give the matter further thought.

Well, that was several days ago and since then I have been thinking off and on about designing a test that could be used to prove the existence of ghosts and at the same time the test would be immune to cheating. And unfortunately, the best thing that I can think of would be use some bit of post-death information that could be readily confirmed

However, I have come to the conclusion that only way such a test could be done is to do something really drastic. For example, have a person randomly pick a card from a deck, then allow that person to study the card for several minutes, then destroy the deck of cards that was used.

Next, drop the picked card into a safe that can be carefully monitored, and then kill the person who picked the card before they could tell anyone what card they picked.

And later, the ghost of the person who was killed could tell what card was picked. And if right, then that would at least be some evidence of showing that at least information can be carried through to the post-death universe.

Ugh!

Sorry, but since the test involves the murder of a person, then clearly such a test is quite impossible, and therefore it may never be possible to obtain objective evidence of ghosts.

Hopefully, one day I will be able to design a less brutal test, but I doubt that I can do so.

 

[JoeTheJuggler]

Just in case anyone is still interested, I had a bit of discussion with 'JoeTheJuggler' about the issue of proof for ghosts and I said that I would give the matter further thought.

Well, that was several days ago and since then I have been thinking off and on about designing a test that could be used to prove the existence of ghosts and at the same time the test would be immune to cheating. And unfortunately, the best thing that I can think of would be use some bit of post-death information that could be readily confirmed

However, I have come to the conclusion that only way such a test could be done is to do something really drastic. For example, have a person randomly pick a card from a deck, then allow that person to study the card for several minutes, then destroy the deck of cards that was used.

Next, drop the picked card into a safe that can be carefully monitored, and then kill the person who picked the card before they could tell anyone what card they picked.

And later, the ghost of the person who was killed could tell what card was picked. And if right, then that would at least be some evidence of showing that at least information can be carried through to the post-death universe.

Ugh!

Sorry, but since the test involves the murder of a person, then clearly such a test is quite impossible, and therefore it may never be possible to obtain objective evidence of ghosts.

Hopefully, one day I will be able to design a less brutal test, but I doubt that I can do so.

And even this test depends on you having a pretty definite idea of the definition of the term ghost in mind. It has to be something capable of retaining and communicating memories without a brain or body.

Again, we have something immaterial with material properties.

 

[Crossbow]

And even this test depends on you having a pretty definite idea of the definition of the term ghost in mind. It has to be something capable of retaining and communicating memories without a brain or body.

Again, we have something immaterial with material properties.

Yes indeed, you are quite correct!

And even if a ghost is properly defined, then that still does not explain how something incorporeal could somehow intelligently interact with us coperal beings. After all, if such a thing were really possible, then I expect that much of our science would be due for a very serious review (to say the least)!

 

[Resume]

Yes indeed, you are quite correct!

And even if a ghost is properly defined, then that still does not explain how something incorporeal could somehow intelligently interact with us coperal beings. After all, if such a thing were really possible, then I expect that much of our science would be due for a very serious review (to say the least)!

As I often point out to paranormal enthusiasts, evidence for "ghosts" would be a world altering event. It would change much of what we think we know about physics for just one example, and I don't think such evidence would be hawked on fringe cable TV shows hosted by nitwits.

 

[Cainkane1]

This is a spinoff of another thread concerning a picture of a "ghost". I realized that while no one responding in that thread really believed that a ghost had been seen, the responses centered around how the picture was probably faked. It got me thinking, what is proof of a ghost? What do people who believe in ghosts point to as proof? Pictures? Is that really enough? It's either a picture of "something" they saw or anecdotal evidence.

If ghosts exist, how would one prove it? Since we know pictures and fables aren't cutting it.

If my premise isn't clear enough, I can elaborate.

Proof of a ghost would be a legitimat picture or video of one who came back and spoke on a regular basies to a group of disbelievers who tried their best to scientifically discredit them. This would have to be an ongoing situation with the spook actively taking part in the investigation to prove the existence of itself.

 

[Hlafordlaes]

It's the material - immaterial thing, as others have said. If you find evidence, you have a real natural phenomenon, and it is not a ghost. Maybe a phase-shifted Klingon (kidding).

If you don't find evidence, well, no evidence.

Damned if you do, damned if you don't.

 

[ZirconBlue]

It's the material - immaterial thing, as others have said. If you find evidence, you have a real natural phenomenon, and it is not a ghost.

The highlighted bit doesn't necessarily follow. It could be that a ghost is a "real natural phenomenon" that we just haven't discovered (or documented), yet.

 

[Hlafordlaes]

The highlighted bit doesn't necessarily follow. It could be that a ghost is a "real natural phenomenon" that we just haven't discovered (or documented), yet.

Hope not!

If so, it would involve some form of measurable state transitions or something. No longer a spectre from an unnatural world (normal def of "ghost"), but a (highly improbable) facet of this one.