burden of proof

This will be short.

"Burden of proof" refers to an argument where one side has to prove their point, and if they don't, then the other side wins. For instance, in court a considered innocent until proven guilty. The burden of proof is laid on the prosecution.

This concept is often introduced into proof-of-god debates, laying it on theists. The assumption is that unless the theist can prove God exists, a normal person observing the conversation, who has heard all the facts and logic, would chose to not believe in God.

In some way this might make sense. In general, it is more probable that something does not exist because there are more things that aren't than things that are. Plus, in our model of the universe we probably start with a blank slate and then introduce objects.

However, this is simply an argument debating a certain unknown. If neither side can prove it one way or the other, do we not simply leave it as unknown? If I can't prove to you that light is a wave, and you can't prove it's a particle, then we leave it up in the air!

In the case of God though, there are rather dire consquences if you chose not to believe in him and find out you're wrong. So 'unknown' does not mean we leave the subject to rest.