why is it not possible to prove a negative?

Question

loads of people were saying it in a question about the existence of god

Answer 1

This is from a scientific point of view. While the rest of the world believes or doesn't believe in things with little evidence, science needs hard empirical evidence before saying something is a fact-evolution is a theory and so is gravity, simply because the scientists don't have all the facts and explanations on these subjects. The problem with a negative like = God doesn't exist, how do you factually prove something doesn't exist. You can imply it does or doesn't exist but getting hard evidence on something negative would be very difficult. Remember science is very, very exacting.

Answer 2

The standard illustration goes like this:
I claim "there's no such thing as a black swan", and point to the fact that I've taken pictures of 10,000 swans and each of them was white.
However just because all the swans I've seen so far have been white is no reason to believe that the next swan I see will not be black.

The point is, you can only provide _evidence_ one way or another - whether it's the existence of black swans, evolution or God. There's no _evidence_ of the existence of God. That doesn't mean that God definitely doesn't exist - it can't be proved.

But how that helps the theist, I don't know. There are plenty of things that might exist even though we've never seen evidence of them - leprechauns, elves, Nessie, Bigfoot, the Flying Spaghetti Monster, etc. What makes God different?

Answer 3

In math and logic there is a standard method of proof 'reductio ad absurdum' where you assume a proposition is true, but if this leads to a contradiction or fallacy, you have disproved the proposition.
The classic example is euclid's proof of the infinity of primes.
On the other hand you cannot physically disprove the existence of god, mermaids, unicorns and other chimera as this would involve an infinite search. QEF

Answer 4

becasue in the real world negative lengths don't exist

Answer 5

Says who?

There is no letter Z in London.