Modern science is based partly on the ability to always doubt. Rather than things being true or false, they are somewhere on a scale of likelihood. Virtually every advance in science has been and will be replaced by better theories as instruments and observations improve. There is not a single thing that science believes is 100% certain. Not one. This is why I don't like the death penalty and don't think it is ever appropriate.

Having said that, I agree with your view of 12 angry men. I too thought that reasonable doubt had been established.