Why do people say you can't prove a negative? (Serious Question)?

Question

Where did this meme come from? Why is it so widely spread among atheists? (Before you attack me, I'm an atheist)

I'm taking "You can't prove a negative" to mean "You cannot prove a proposition whose main logical connective is a negated existential quantifier."

However, that second statement is completely false. There are plenty of provable propositions that are negatively existentially quantified. For example, it is provable that there are no round squares. It's also provable that there are no natural numbers greater than all other natural numbers.

Am I misinterpreting the statement "You can't prove a negative" or do people simply regurgitate the meme because it seems supports their argument?

Personally, I think we should all reject "You can't prove a negative" in favor of Burden of Proof considerations. Can anybody enlighten me? Thanks in advance.

Answer 1

You CAN prove a negative, at least in certain logical situations (for example, it is a common proof showing at the square root of two is not rational).



However, what you're referring to is that you can't EMPIRICALLY prove a negative.

You have to empirically show the existence of whatever phenomenon you're talking about.
You can't "prove" that this phenomenon doesn't exist, rather, it is assumed not to exist unless someone can demonstrate that it does. Null/Alt hypotheses in other words.



In a purely statistical sense, saying "it is provable that there are no round squares," means that, in the physical world, you accept that there are no round squares without proof......if someone were to claim that round squares exist, this would require empirical proof.

Hope that helps.

Answer 2

IS it provable that there are no round squares?

You can't prove non-existence as you cannot check every bit of the universe at the same time to confirm something material does not exist. This, I believe, is what people mean when they say you can't prove a negative. You can try to prove it through reasoning (like with round squares), but you can't actually show that there isn't one out there somewhere. What do we really know about the universe?

I do agree that it is not correct to say we can't prove a negative. Perhaps "we can't prove this negative" would be more appropriate.

Answer 3

a million. Many negatives statements could be shown. "no one in this room has glasses" could be incredibly ordinary to instruct as an occasion. 2. Extinction isn't a damaging assertion. that's not even a sentence.

Answer 4

Balaam's has it right on the money. It doesn't work with (some) things subject to logical proof, but in the empirical world it holds.

In any case, as used in this particular arena, the phrase is just a shorthand for 'you can't prove (empirically) that a deity doesn't exist' - something that is regularly required to counter those who feel that God's non-disprovability is somehow evidence of his existence.

CD

Answer 5

There are what are called "logical fallacies" and you can find them listed in various websites that deal with the topic.

What it is referring to are claims that try to prove something through a lack of evidence or no evidence. People in religion do this all the time:

"The Bible doesn't say you can use musical instruments in church, therefore it is wrong."

This is an example of the logical fallacy of trying to prove something through a negative.

"The Bible does not condone birthday celebrations, so they are wrong and a sin"

What's funny is when you use this logic against them in regards to something they believe.

.

Answer 6

Those of us who've had formal training in rhetoric recognise that technically, you can't prove a negative, you can only prove an improper hypothesis.

"There are no round squares" is not a proper hypothesis, even if it is true. The proper hypothesis version of it is "squares are not round" which is, in fact, a positive assertion.

"God does not exist" is not a negative assertion. It warrants discussion.

The first part of it, of course, is the definition of god.

If you claim there are no omnipotent, omnipresent, omniscient, omnibeneficient deities, I agree wholeheartedly.

However, if you say that there does not exist in the whole of the world a minimum of one species with superior technology to our own that would allow said species to meet the definition of god outside of Abrahamic religions, I strongly disagree.

By the way-
EVERY two dimesional square is, indeed, round, if by round you mean possessing a curve, not spherical. This is because a plane curves.

Answer 7

"I know the myth of "you can't prove a negative" circulates throughout the nontheist community, and it is good to dispel myths whenever we can. As it happens, there really isn't such a thing as a "purely" negative statement, because every negative entails a positive, and vice versa. Thus, "there are no crows in this box" entails "this box contains something other than crows" (in the sense that even "no things" is something, e.g. a vacuum). "Something" is here a set restricted only by excluding crows, such that for every set S there is a set Not-S, and vice versa, so every negative entails a positive and vice versa."

Answer 8

You can prove negatives (in as much as you can prove anything), you just can't prove a universal negative. I could say that there is no such thing as blue speckled rocks, but since we'll never catalog every rock in the universe, we'll never be certain that there are no blue speckled rocks. For that matter, you can't really prove anything. There is always a possibility, however small, that you're wrong on some given topic. It may be incredibly unlikely, but it's still there.

Answer 9

Many theists reject burden of proof. They don't seem to understand it.

However, it is true that without being internally inconsistent, a negative cannot be proven 100%.

I can't prove the earth ISN'T hexagonal. But I can prove the earth is relatively spherical.

Answer 10

A negative. There are no round circles. That is not a negative. zero is not a negative. You can't prove something doesn't exist. You can create a model to see if something exists and find that it doesn't.

IE Is man made of clay?
Disect a human body.
Nope.

Man is not made of clay.