Why is it impossible to prove something DOESN'T exist?

Answer 1

Actually, it *is* possible to prove the non-existence of certain things. As others have pointed out, self-contradictory things are easily shown to not exist. Another possibility happens when the existence of something implies the detectability of that thing in certain circumstances. For example, I can demonstrate the non-existence of an elephant in my room by simple observation since an elephant in my room would be very observable. A similar thing can be done with certain subatomic particles which are *required* to show up in certain situations.

The impossibility comes in situations that are not self-contradictory, but where no situation will require the observation of the thing sought. For example, we cannot show that unicorns don't exist since we only have a finite ability to check for them, yet they could potentially be anywhere in an infinite universe. We might be able to demonstrate that unicorns don't exist on earth, though.

Answer 2

Existence is a matter of perception, we can only attempt to prove or even suspect the existence or non-existence of something we can perceive with our senses, augmented or normal, or by use of our intellect and imagination. Therefore since perception is a highly individual experience no one thing can ever be proven to exist or not exist as long as there is more than one observer. More than one observer introduces the necessity of interpretation and the communication of thoughts and perceptions; a task that is inherently open to misinterpretation and mistakes, casting doubt on any proof presented.

However, this said, the current definition of 'proof' as listed in the dictionary defines it as establishing truth or validity through persuasive or compelling argument. This would mean that it is possible to prove that anything either exists or does not, depending on how persuasive the speaker is, or how gullible the listener is.

You may also wish to consider some of the theories of modern science which state that the act of observing something changes it, in which case it would be something else and not the object you first assumed existed. Quantum theory states that if an object is not observed then it exists in all states at once, both existing and not existing and all states in between.

Hope I gave you some food for thought.

Answer 3

It depends on the definition of the thing whose existence is to be proven. If the thing, for instance, is "an odd number divisible by 2 with no remainder", we can easily disprove its existence.

If you are talking about material things, again, it depends on how we define things.

One problem we run into is that the definition of all things depends on language, and language is a set that cannot be both complete and definite (Godel's incompleteness theorem). Therefore, there is always room for doubt that the definition was correct.

In practical terms, though, we can usually make some headway.

You are right in assuming it's a difficult task, though. Spinoza tried to prove the existence / nonexistence of God, as did Aquinas (and for that matter, less rigourously, C.S. Lewis in his book "Mere Christianity"), and Spinoza either argued from faulty assumptions or concluded the answer was unknowable. Aquinas argued from the assumption that his conclusion was already true.

It's not adequate to start with statements like "You've got to believe in something", or "there HAD to be something before the first thing..." because many people don't believe, and prior cause is an element of the conclusion demanding proof; in one case it disproves a central tenet of the argument, and in another, the logic is faulty.

Answer 4

Because existence has relative meaning. Like with aliens. People say that there are aliens, and others say that there aren't. Because of the people that think there are, it is impossible. It is only possible to prove somehting exists. Just because you can't see it doesn't mean it's not there, but if you see it, well then there it is.

Answer 5

It is not impossible. The difficulty in doing so depends on the scope of the claim.

If the claim is "no socks exist in my sock drawer", You could prove that claim by producing your empty sock drawer.

If the claim is "no hobbits exist in my sock drawer", You could prove that claim by the same method as above.

If you make those same claims but applicable to the planet, the universe, or beyond... the difficulty becomes greater due to the impracticality of producing a planet or universe that is entirely and simultaneously free of the thing claimed not to exist.

Answer 6

Well, if something DIDN'T truly exist, there would be no need to prove or disprove its existence or non-existence in the first place.

For me to prove the existence of a thing, I would need to be able to perform at least one test on that thing to empirically determine its state of existence. If the thing doesn't exist in the first place, how can I perform a test on it? And if the thing is accessible to me whereby I can test it, isn't that in itself proof that it exists?

Therefore, there would be no need to prove it doesn't exist, when in fact it DOES exist. And if it exists, then it would by default be impossible to prove its non-existence. Likewise, if it didn't exist, it would be impossible to prove it DID exist.

SIDEBAR: To piggyback on another statement made here, it is intriguing to think that when we observe ANYTHING, it is not how that thing exists at that instant, but rather in the past. When we view stars, as we know, the light we see has actually left a given star years, decades, centuries, millenia, or eons (etc...) ago.

In this Einsteinian vein, if I look at the coffee cup on my desk, for instance, the light that illuminates that cup took SOME period of time, however short, to reach my eye (and THAT information takes some amount of time to be processed by my brain). In effect, EVERYTHING we see is in the [very recent] past, but is still an articial re-creation, only an IMAGE of an object located in reality, therefore, not the reality itself. Everything we see is, in effect, instant replay processed by our amazing brains.

SIDEBAR 2: There are concepts which may not "exist," but only because their existence is logically impossible. For example, boiling ice, or the aforementioned "married bachelor" are absurdities, given the strictures of our language. Akin to this is the age-old question "Could God create a rock which is too heavy for him to lift?" It's an inappropriate question, because it is logically fallacious.

Love, Jack

Answer 7

Anything we see, feel, smell, hear, and then on a more subtle level, we experience emotionally, and our imagination and fantasies, none of this comes from nothing. There's a source for every memory, dream, feeling, fantasy, whatever...it all comes from somewhere, sometime. Just because we can't remember it, dosn't mean it dosn't exist. So it is impossible to prove that "someTHING" does not exist..if it didn't exist, it wouldn't be someTHING....isn't there a word for this situation?

Answer 8

Religious people argue that, although they cannot prove that god exists, atheists cannot prove that god does not exist. This argument is inherently faulty.

It is logically impossible to prove that an object or event does not exist. However, it is the essence and the backbone of science to provide evidence that something does exist. If something exists, such as energy, matter or space, it manifests itself to us by objective evidence. We can measure such manifestations or we can take objective images of them.

It is axiomatic in the affairs of man, and steeped in common sense that, whoever makes a claim, has to prove its validity. The burden of proof is always on the person making the claim. Extraordinary claims require extraordinary proof.

If a person should claim that the moon is made of green cheese, he has to prove that the moon actually consists of green cheese, instead of rock, as established by previous, hard, factual, objective evidence. It is logically impossible and absurd to demand that, whoever does not accept the claim that the moon is made of green cheese, should disprove the claim.

Answer 9

It is impossible to prove something doesn't exist because lack of evidence does not serve as evidence. Just because you've never seen a million dollars, doesn't mean it doesn't exist.

Answer 10

It goes both ways. People often times has to prove something does exist as well. There are only a certain amount of absolute truths in this world and there are a multitude of believed truths. The important thing is knowing the Truth.