If a religious person asks me to prove that god does not exist, I freely concede that I cannot do so. The best that I can do is to invoke the Laplacian principle that I have no need of hypothesizing god’s existence to explain things. But clearly most people feel that theydo need to invoke god in order to understand their lives and experience. So how can we resolve this disagreement and make a judgment about the validity of the god hypothesis?

Following a recent posting on atheism and agnosticism, I had an interesting exchange with commenter Mike that made me think more about this issue. Mike (who believes in god) said that in his discussions with atheists, they often were unable to explain why they dismissed god’s existence. He says: “I find that when asked why the ‘god hypothesis’ as Laplace called it doesn’t work for them, they often don’t know how to respond.”

Conversely, Mike was perfectly able to explain why he (and other believers) believed in god’s existence:

The reason is that we have the positive proof we need, in the way we feel, the way we think, the way we act, things that can’t easily be presented as ‘proof’. In other words, the proof comes in a different form. It’s not in a model or an equation or a theory, yet we experience it every day.

So yes, we can ask that a religious belief provide some proof, but we must be open to the possibility that that proof is of a form we don’t expect. I wonder how often we overlook a ‘proof’ – of god, of love or a new particle – simply because it was not in a form we were looking for – or were willing to accept.

Mike makes the point (with which I agree) that it is possible that we do not have the means as yet to detect the existence of god. His argument can be supported by analogies from science. We believe we were all bathed in electromagnetic radiation from the beginning of the universe but we did not realize it until Maxwell’s theory of electromagnetism gave us a framework for understanding its existence and enabled us to design detectors to detect it.

The same thing happened with neutrinos. Vast numbers of them have been passing though us and the Earth but we did not know about their existence until the middle of the 20th century when a theory postulated their existence and detectors were designed that were sensitive enough to observe them.

So electromagnetic radiation and neutrinos existed all around us even during the long period of time when no one had any idea that they were there. Why cannot the same argument be applied to god? It can, actually. But does that mean that god exists? I think we would all agree that it does not, anymore than my inability to prove that unicorns do not exist implies that they do. All that this argument does is leave open the possibility of a hitherto undetected existence.

But the point of departure between science and religion is that in the case of electromagnetic radiation and neutrinos, their existence was postulated simultaneously along with suggestions of how and where anyone could look for them. If, after strenuous efforts, they could still not be detected, then scientists would cease to believe in their existence. But eventually, evidence for their existence was forthcoming from many different sources in a reproducible manner.

What if no such evidence was forthcoming? This has happened in the past with other phenomena, such as in 1903 with something called N-rays, which were postulated and seemed to have some evidentiary support initially, but on closer examination were found to be spurious. This does not prevent people from still believing in the phenomenon, but the scientific community would proceed on the assumption that it does not exist.

In the world of science the burden of proof is always on the person arguing for the existence of whatever is being proposed. If that evidence is not forthcoming, then people proceed on the assumption that the thing in question does not exist (the Laplacian principle). It is in parallel to the legal situation. We know that in the legal context in America, the presumption is that of innocence until proven guilty. This results in a much different kind of investigation and legal proceedings than if the presumption were guilty until proven innocent.

So on the question of god’s existence, it seems to me that it all comes down to the question of who has the burden of proof in such situations. Is the onus on the believer, to prove that god exists? Or on the atheist to argue that the evidence provided for god’s existence is not compelling? In other words, do we draw a parallel with the legal situation of ‘presumed innocent until proven guilty beyond a reasonable doubt’ and postulate a principle ‘non-existence until existence is proven beyond a reasonable doubt’? The latter would be consistent with scientific practice.

As long as we disagree on this fundamental question, there is little hope for resolution. But even if we agree that the burden of proof is the same for religion as for science, and that the person postulating existence of god has to advance at least some proof in support, that still does not end the debate. The question then shifts to what kind of evidence we would consider to be valid and what constitutes ‘reasonable doubt.’.

In the next few postings, we will look at the kinds of evidence that might be provided and how we might evaluate them.