Here’s how I would approach the problem of flying bedside lamps:
[ul]
[li]I will NOT think “Aha, a ghost! And I think I can prove it too.” I’ll think “hmm, something moved the lamp, I’m going to find out what.”[/li][li]Try mundane explanations (prank, poor recollection, etc). If they don’t fit:[/li][li]Replace the lamp and try to reproduce the phenomenon[/li][li]Find out if other people have observed similar flying lamps[/li][li]If I succeed in reproducing the phenomenon or find other documented cases, I’d find out what the common factors are that may lead to lamps flying. (Does it happen repeatedly in specific places? Specific type of lamp? Only when a specific type of person is in the room?)[/li][li]Think of a hypothesis (or several) that explains the phenomenon, given the above information.[/li][li]Test the hypothesis. Or if more than one, design experiments to eliminate some of the hypotheses.[/li][li]Repeat the hypothesis/experiment cycle. If the only hypothesis that fits the observation involves some type of ghost, you’ve proven the existance of a ghost.[/li][/ul]
That’s the thing. 
So far, in ghost mythology, the only thing that’s a concrete definition is that a ghost is a disembodied spirit of a dead person.
Different cultures put different characteristics on ghosts–some ghosts are invisible, some aren’t; some have magical powers, some don’t; some are violent and aggressive, some are peaceful and helpful.
I guess you’d have to sort through all the folklore and find some common attributes…
Here is a concise introduction to existence. If you are curious about such things, you will find it to be a fascinating read.
In other words, the Scientific Method. 
Personally, if my bedside lamp got thrown at me, I wouldn’t think–I’d run!
Thanks!
I thought that was your question, i.e. how one would apply the scientific method to the question of ghosts. If not, what exactly are you asking?
By the way I should stress that a scientist would not pull a hypothesis out of thin air (“ghosts exist”) and start from there, attributing various phenomena and qualities. The scientific method is to start with an unexplained phenomenon. If you don’t have a well-documented, repeateable phenomenon that defies conventional explanation (i.e. with current knowledge of physics), you don’t have anything to work with.
But the scientific method cannot prove that anything exists, let alone ghosts. It can’t even prove hypotheses true; it can only prove them false.
That’s why I think–as stated above–that the scientists would first have to agree on what apparent behaviour is attributable to a ghost (agreeing on what makes up a ghost) before going about proving that a ghost, by their definition, exists.
My question: simply put, what is a ghost?
Yes, those semantic musing are interesting-- in an obscure sort of way. Let’s just say we define “scientific proof” as what results from applying the Scientific Method to problems and move on.
Well, what do you think a ghost is? That’s all you really need to start with. You were sitting in your room, and you saw a lamp go flying by as if by its own volition. You wonder: “Could it have been a ghost that lofted my lamp?” Now you have to define “ghost”. Go ahead. You may simply assume a ghost is a disembodied spirit of a dead individual that can move solid objects despite having no physical form. Great, there’s your definition of a ghost. Now all you have to do is find a way to demonstrate convincingly that such an entity threw your lamp. You could say that, rolled up into the hypothesis (a ghost threw my lamp) is an assumption that ghosts exist. That’s fine; if you don’t care about being consistent with conventional wisdom (and it’s often useful to throw common sense out the window if you’re stuck for new ideas), you can just take that hypothesis, with its inherent assumptions, and run with it.
You might demonstrate that a ghost did indeed throw your lamp.
You might find a more mundane explanation.
You might not be able to show that, while your definition of a ghost is not applicable to what you observed, you are still unable to explain the lamp toss. You may then go about testing different hypothesis, with different assumptions.
Sometimes scientific discoveries require intuitive leaps, where as-yet unobserved agents fit into a good model that explains a particular phenomenon in a way you find satisfactory. Francis Crick’s adapter hypothesis is one example that springs to mind. Stumped for a better explanation as to how mRNAs get translated into proteins, he posited an adapter between the mRNA sequence and the peptide sequence it encoded, and even predicted some of the qualities it might have, even though he did not know quite what this adapter could be. Soon Crick, et al. discovered the tRNA, and the rest is history. All Crick had to start with is the knowledge that there are mRNAs, polypeptide sequences that are encoded by those mRNAs, and something of a black box in between, inside of which which somehow those sequences were translated from mRNA to protein. People asked Crick at the time he formulated the hypothesis “So, what do you thing these adapters are?” He made some assumptions, and ran with them. In my oppinion, it’s one of the greatest intuitive leaps in all of molecular biology.
Now what the hell happened to my brain when I put that little gem of a thought together? Here’s what I should have said:
You might only be able to show that, while your definition of a ghost is not applicable to what you observed, you are still unable to explain the lamp toss. You may then go about testing different hypothesis, with different assumptions.
Ghosts do not exist, so the question is meaningless. A ghost can be whatever you define it to be, as an act of fiction.
Ahh, but what if they did? All we know about ghosts is we’ve never proven there are such beasties.
A compassionate empiricist might try to discourage someone from looking further for ghosts, since the likelihood of their existence seems to utterly remote. But that’s just common sense! Common sense be damned! Kytheria wants to look for ghosts; so let her look! There’s nothing “unscientific” about making the attempt.
Unscientific would be if, after having a good empirical go of it, she chose to ignore her negative findings and insist that despite all evidence to the contrary, ghosts must be.
If ghosts are shown to exist, scientifically, part of the “showing” will be to define what properties they have. Until such time, there is nothing wrong with saying “ghosts don’t exist” any more than saying “leprechauns don’t exist”. Otherwise, there is no meaning to the statement: “I exist”, since nothing can be said not to exist.
DON’T DO IT! (The pay is lousy!)
And **John Mace ** is the final authority on this?
Pardon me as I exit, laughing!
That was already settled in another thread, Kyth. You can read through the entire four pages that got us there, but here’s the one page that has the definition, as provided by Fish.
No one has been able to refute it or improve it yet.
Are you crazy? I wonder how much John Edwards and James Van Praag make?
I’m sure it’s substantial. You just have to know how to make a show and song and dance about it.
Well, as long as you’re willing to qualify the statement with a “as far as I know” kind of disclaimer. I don’t think the concept of “existence” is negated just because one is willing to entertain the possibility of the unobserved. The trouble starts when, despite all efforts to observe prove fruitless, one insists the unobservable thing must exist anyway, just because. You can say “well, I’ve never seen it, though I tried my damnedest to, so I think it’s highly unlikely there is such a thing”, but that doesn’t mean you have to give up on acknowledging your own existence too.
There is a point, I think, where the search for something is so exhaustive that any sane mind must grasp its lack of reality. One could drain all of Loch Ness, and a few folks out there would continue to insist there is a Monster. Sure, if I can’t look at the empty bed of Loch Ness, see with my own eyes there is no Pleiosaur or whatever living in its depths, and admit there is no Monster there, then I probably am no longer qualified to attest reliably to the existence or non-existence of much of anything.
But one could simply be ignorant. They might have heard of ghosts, and since the world is big, and not every nook and cranny has been examined, figure the existence of ghosts isn’t out of the question. It’s not a completely irrational hypothesis. The lamp investigation suggested above can’t disprove ghosts the way the Loch Ness experiment can disprove the Monster. It can only disprove that a hypothetical kind of ghost was responsible for the flying lamp. It seems extremely likely that any and all tests of the existence of ghosts will come up empty, and that’s it’s a waste of time considering there are so very many perfectly mundane explanations for ghost sitings. But is the matter of the existence of ghosts truly settled? That may be a matter of oppinion. The idea of ghosts is certainly ridiculous. But utterly impossible? Good luck trying to prove that!
Let’s keep in mind that it’s not for lack of trying that there is no scientific evidence for the exhistence of ghosts. One would indeed be on shaky ground to say definitifely that extraterrestrial life does not exist, but I think we’re pretty safe on ghosts-- unless there are ET ghosts.