How do you prove something doesn't exist?

[notoverrated]

not sure if this is the right spot for this but seemed like a deep question to me so here we go.

How do you prove that something doesn't exist? i mean its easy to prove that something does exist, all you have to do is find it. but how do you PROVE something doesn't exist....? And when do you stop looking?

[Sakari]

You can not, it is just a scape goat phrase......

Good read:

Let's sum up. If "you can't prove a negative" means you can't prove beyond reasonable doubt that certain things don't exist, then the claim is just false. We prove the nonexistence of things on a regular basis. If, on the other hand, "you can't prove a negative" means you cannot prove beyond all possible doubt that something does not exist, well, that may, arguably, be true. But so what? That point is irrelevant so far as defending beliefs in supernatural entities against the charge that science and/or reason have established beyond reasonable doubt that they don't exist................... http://www.psychologytoday.com/blog/believing-bull/201109/you-can-prove-negative

[Professor T]

Tricky Question...............

I dont think anyone can truely proove that something doesn't exists..

Sakari's thread as tried to disprove the existence of Evil Spirits and failed imo.. http://www.unexplain...pic=181521&st=0 Though I am sure he and others will disagree with my opinion on that..

If something doesn't exist, but we are attempting to disprove it's existence then imo there is no logical way it can be disproved.

Edit: lol, Sakari bet me to it.

Edited February 24, 2013 by Professor T

[Sakari]

Edit: lol, Sakari bet me to it.

And you used me as an example.....

[Professor T]

And you used me as an example.....

Had just been reading your thread so I was geared up for this one..

I don't think this thread will go to 127 pages.. We seem to have covered the answer in 2 posts..

Though I'm sure there'll be plenty of other good answers too.

Edited February 24, 2013 by Professor T

[shrooma]

the answer is quite simple really.

what you do, is come up with an interesting theory, make an UM thread out of it, and you can guarantee that within half an hour you'll have a hundred people all proving to you that the objective of your theory doesn't exist.....

[Sakari]

the answer is quite simple really.

what you do, is come up with an interesting theory, make an UM thread out of it, and you can guarantee that within half an hour you'll have a hundred people all proving to you that the objective of your theory doesn't exist.....

Theories can be debated, and theories are not " existence" .

Now facts are a different story.

[Professor T]

Hmmmmmmmm, the question of proving that something doesn't exist is a Paradox.

This might help..

http://www.youtube.com/watch?v=5an8pvFjWZw

[SHaYap]

to prove something 'doesn't' exist , we only have to disprove that it 'does' exist

[ChrLzs]

To be a little more precise.. Of course you can theoretically disprove something exists, but only IF it is detectable and you constrain the boundaries of it..

Eg let's say you have an empty shoebox in front of you (lid off!).

Can you say with absolute 100% certainty that:

- there are no elephants in it? YES, you can.

- there is no life in it all? NO - realistically you could not sterilise and microscopically examine it (and you'd need to be in a clean room..)

Between that silly example of a shoebox and finding bigfoot/nessie/aliens, there is obviously a wide range of different criteria - in many cases it will be impossible (or extraordinarily difficult or prohibitively expensive), but not all.. Just depends on exactly what you are trying to prove.. (and where)

[Lilly]

I think people over complicate this. Basically, if there is no evidence that something exists then you have to go with nonexistence. You don't *prove* something doesn't exist per say, rather the lack of evidence demonstrates for nonexistence. If one suddenly gets evidence that something does indeed exist then you've essentially *proven* its existence. In other words, one proves 'existence' not 'nonexistence'.

[shrooma]

Theories can be debated, and theories are not " existence" .

Now facts are a different story.

.

I think you just proved that your sense of humour doesn't exist.

do I win a prize or anything....?

:-)

[SHaYap]

not :

to prove something 'doesn't' exist , we only have to disprove that it 'does' exist

then ?

to disprove something 'doesn't' exist , we only have to prove that it 'does' exist

yes ? or :

to disprove something 'does' exist , we only have to prove that it 'doesn't' exist

then ?

to prove something 'does' exist , we only have to disprove that it 'doesn't' exist

~edit : I don't remember

Edited February 24, 2013 by third_eye

[Sakari]

.

I think you just proved that your sense of humour doesn't exist.

do I win a prize or anything....?

:-)

Your reply looked serious enough to me.....Considering so many say the same thing, and hate " skeptics " or any debate at all.

If it was in humor, ( we do not spell it with a " u " after the " o " ) it must have been that " dry English " style. Us Americans never did get that.

And no, you do not win a prize.

And also, my reply is mostly in humor.

Edited February 24, 2013 by Sakari

[shrooma]

how to prove the blue square in your hand doesn't exist-

1) look at your hand.

2) is there a blue square there?

3a) yes.

3b) no.

4a) the blue square exists.

4b) the blue square doesn't exist.

.

can I have my prize now, I want to go to bed?

:-)

[Sakari]

not :

to prove something 'doesn't' exist , we only have to disprove that it 'does' exist

then ?

to disprove something 'doesn't' exist , we only have to prove that it 'does' exist

yes ? or :

to disprove something 'does' exist , we only have to prove that it 'doesn't' exist

then ?

to prove something 'does' exist , we only have to disprove that it 'doesn't' exist

~edit : I don't remember

Above reply gives me a head ache.

[shrooma]

Your reply looked serious enough to me....

.

nope, it was definitely in jest. slightly barbed maybe, towards the way some people on this site have a rigid, 'i'm right, so you're wrong' attitude that discourages proper discussion, but done in jest nonetheless.

[Sakari]

.

nope, it was definitely in jest. slightly barbed maybe, towards the way some people on this site have a rigid, 'i'm right, so you're wrong' attitude that discourages proper discussion, but done in jest nonetheless.

As said, see so many like that, that are " serious"....

Sorry, my bad.

[Professor T]

I think people over complicate this. Basically, if there is no evidence that something exists then you have to go with nonexistence. You don't *prove* something doesn't exist per say, rather the lack of evidence demonstrates for nonexistence. If one suddenly gets evidence that something does indeed exist then you've essentially *proven* its existence. In other words, one proves 'existence' not 'nonexistence'.

I think anyone of any Faith would diagree with that if the question of existence was about their god.

And we can't dis-prove Faith now can we. It's a viscious circle.. It sure makes interesting reading sometimes though.

Edited February 24, 2013 by Professor T

[_Only]

A good way to prove something doesn't exist is by proving that it's not possible.

[Rlyeh]

It's easier if the attributes are mutually exclusive then logic alone dictates it doesn't exist, eg, a square circle.

[White Crane Feather]

You can not, it is just a scape goat phrase......

Good read:

Let's sum up. If "you can't prove a negative" means you can't prove beyond reasonable doubt that certain things don't exist, then the claim is just false. We prove the nonexistence of things on a regular basis. If, on the other hand, "you can't prove a negative" means you cannot prove beyond all possible doubt that something does not exist, well, that may, arguably, be true. But so what? That point is irrelevant so far as defending beliefs in supernatural entities against the charge that science and/or reason have established beyond reasonable doubt that they don't exist................... http://www.psychologytoday.com/blog/believing-bull/201109/you-can-prove-negative

Rediculous. Yes you cannot proove a negative this is true.. Double negatives always have problems, but rational people do not need the aggregate to dictate truth by plural reasoning to what they know is true. Some things do not lend themselves to repeatability through demand.

[SHaYap]

particles or waves ?

[ali smack]

Prove what doesn't exist?

[eight bits]

First, it depends on what you mean by "proof." Two of the most famous early proofs, both attributed to Euclid, are non-existence results. There is no largest prime integer, and there is no pair of integers whose ratio squared is two. Impossibility proofs remain commonplace. Kenneth Arrow shared the 1972 (Memorial) Nobel Prize in Economics, in large part for a result called, sensibly enough, "Arrow's Impossibility Theorem." There is no voting scheme which has all of a short list of "reasonable" properties you might want in a "democratic" voting method.

The expression is also used when a certain method will surely fail to produce any negative result, but might produce a positive one. For example, the usual kind of frequentist statistics never advocates accepting the null hypothesis, but sometimes supports the alternative, usually positive hypothesis. So, you literally "can't prove a negative," the truth of the null hypothesis, by those methods. Similarly, it is obvious that brute-force search will never clinch the non-existence of Bigfoot (you'd have to look everywhere simultaneously), while it might catch one. What is less obvious is that brute-force search isn't the only way to approach the problem.

What people mostly complain about is that it is difficult to establish non-existence, while easy to fantasize about an investiagtion that yields an example. So, you wouldn't even know where to begin to accumulate evidence that Bigfoot doesn't exist, but you can imagine somebody showing up with one if such a thing does exist.

Well, that's not very interesting. Of course it's easier to fantasize doing something than it is actually to do just about anything.

I understand the frustration of, say, atheists, when challenged that "You can't prove God doesn't exist." One correct and responsive rejoinder would be "I have never denied the theoretical possibility, but we are debating how likely it is that you, so very particularly, have the faintest rational basis for asserting not only that he exists, but that at one time, he disliked his people eating scallops wrapped in bacon, but that's OK by him now."

It would be also admissible for an atheist to reply "I cannot show God's non-existence because I have different standards for showing things than you do. I demand evidence. If instead, and like you, I allowed faith to substitute for evidence, then I assure you, my faith in God's non-existence would shine forth as brightly as your own."

B&M about the non-existent impossibility of establishing true negatives with the same confidence that true affirmatives are often established is balonious. Under no circumstances ought any story about why somebody has paltry evidence be confused with actual evidence favoring the person's position.