Cats and Frogs

I was recently asked why we non-theist/atheist types maintain that it is not necessary to “prove a negative”.  The challenge emerged after someone had asserted that:

            (the atheist) argument is based on two premises

1.    There is no evidence for God

2.    Atheists are not under any burden to prove no God exists

Here’s my response:

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It's not so much about proving a negative as proving something that is not falsifiable. Say we had a very large number of boxes in front of us. Before we open any, I make the claim that at least one of the boxes contains a cat. You, on the other hand, say that you don't know what is in the boxes. We then open 100 boxes and not one of them contains a cat. Instead each and every one of them contains a small frog.

We now reassess our predictions. You say that the boxes might all contain frogs, while I stick with my cat theory. Then we open a thousand more boxes. They all contain frogs.

We both have the opportunity to reassess our theories. You say that the boxes probably all contain frogs, while I stick with the idea that one box contains a cat.

We open a million boxes and they all contain frogs. Hopefully, you get the idea now. I'm now sounding a bit silly to still be hoping for a cat.

How many more boxes do we need to open to prove that I am wrong about the cat? All of them?

Ah, I say, but perhaps there was a tiny cat inside one of the frogs, we don't know for sure that that is impossible. So we start cutting up the frogs. How many frogs do we need to dissect? All of them?

Ah, I say, but do we know that that was all the boxes? Perhaps there were boxes that we didn't see or that got moved while we were paying attention to the ones we were opening.

So long as I stick to my guns, you can't prove that none of the boxes contains a cat, and I haven't even started redefining what cat means yet.

Now think of "cat" to mean "god" and "frog" to mean "nature or rational science" and perhaps you'll understand why we don't feel obliged "to prove a negative".

I really do hope this helps.