What is the probability of god, assuming the concept of god is coherent? Many have argued for a probability. Others, including me, think that the notion of a probability of god is meaningless. This to me is done for two reasons: 1.) It is not as if there is some cosmic roulette wheel where god is one option and 2.) God either does or does not exist already so the “real” probability would be 0 or 1.

Suppose then that one assigns a null probability to god. How does one determine how reasonable it is to believe in one? It becomes hard to compare beliefs especially if one chooses to assign null probabilities to other beliefs such as fairies or whatever else. How does one compare?

  • yeah i'm sympathetic. i do something similar with 'existence' (don't ask me what that means)
    – user67302
    Aug 17 at 8:06

4 Answers 4


God either does or does not exist already so the “real” probability would be 0 or 1.

Not true. There are innumerable definitions of God. They range

  • From Spinoza's God = Universe ie pantheism
  • ... through panentheism — Spinoza is true but Mainstream Christianity is also true
  • Christian God
  • Pastafarianism — explicitly set up to invalidate it's own 'God'
  • Much much else not on this spectrum

So the real question about God is not whether He (she it) exists, but what do you mean when you use the word.

To use an analogy from logic: You can argue whether a formula is valid (always true), contradictory (always false) or conditionally true ie depending on the free variables.

But all this is itself conditional to the formula being well formed

To quote the physicist Pauli you can be right wrong and not even wrong.

Does God exist?

needs not Y/N but a P(auli) answer.

In any case, here's an unassailable probability argument why believing in something God-ish trumps not believing

All but five of the 263 centenarians we interviewed belonged to some faith-based community. Denomination doesn’t seem to matter. Research shows that attending faith-based services four times per month will add 4-14 years of life expectancy.

Blue Zone
Or wiki if you prefer...

  • I agree with you but I think this is missing the point of the question. I’ll edit the question and add “assuming the concept is coherent” to it. Aug 17 at 7:28
  • That's necessary of course but not sufficient. There are fairly well established concepts of God for which few would deny existence. Spinoza is an extreme which I gave. There are many others. In your case, from your multiple questions against God I'm guessing your God is a personal being who created the universe. But you need spell that out
    – Rushi
    Aug 17 at 7:29
  • What is a well established concept of god whose existence few would deny? Aug 17 at 7:36
  • Start with the 1st: Spinoza. The universe is non existent How often would you see this view? [One could make a case for it but that would be quite a fringe viewpoint]. Then there is Native American God is not a noun/ God is a verb. Etc etc
    – Rushi
    Aug 17 at 8:00
  • Even within Christianity, the God of Jesus, of Moses and of Adam are quite different
    – Rushi
    Aug 17 at 8:11

The purpose of probability is to reduce unknowns and imponderables to something intellectually manageable. I mean, when we roll a die our minds are incapable of assessing all the forces involved to determine an exact outcome. Probability merely puts limits on that unknowability, telling us we have a one-in-six chance of getting any particular outcome.

The point is that probability itself isn't going to help us on this issue; the divine (or whatever) can always exist in the error term.

Gods are one way people make meaning in the world; probabilities are another way that people make meaning. The social problem doesn't lie in the way one chooses to make meaning; it lies in that nihilistic urge to destroy the meanings that others try to make.


It is impossible to assign a meaningful probability to the truth of an idea such as the existence of some god. There are aspects of religion that you can assess logically. For example, you can be logically confident that if n religions are mutually contradictory, at least n-1 of them must be false. You can also feel justified in questioning the core beliefs of a church if they change with circumstances, which rather implies that they are not absolute truths. You can observe with some confidence that a person's religious beliefs are likely to be determined by the circumstances into which they are born and in which they are reared, which suggests that such beliefs are a matter of social conditioning. Given all that, you might be inclined to the view that a belief in god is superstitious nonsense, or you might be happy to accept your religious beliefs in the same way as you accept lots of other socially conditioned beliefs. Trying to decide whether to believe in god by allocating a probability to the idea is like trying to allocate a probability to statements such as 'it is important to exercise your vote', or 'Madonna is better than Beyonce', which are matters of belief rather than fact.

  • "Models which incorporate a particular powerful being of such and such description, which can be propitiated by prayer and oblation, and which shall be called So and So, reliably predict reality" is a perfectly good bit of falsifiable logical positivism. I think it's false, but it's fairly easy to measure its probability. Just propitiate as instructed, ask for thunderstorms, and compare the results to the null hypothesis. Voila, P(Thor) or whatever.
    – g s
    Aug 17 at 16:36
  • That wouldn’t measure the probability of the hypothesis though. It would just measure the probability of whatever outcome occurs by chance. P (E|H), not P (H|E). The latter is arguably nonsensical Aug 17 at 17:25
  • If only there was some formula which related one in terms of the other and measurable frequencies.
    – g s
    Aug 17 at 18:11
  • Creating a formula, even if coherent, doesn’t imply that it models reality. Bayes theorem wouldn’t work without priors, and it is nonsensical to talk about the priors of god. There is no evidence to suggest god exists. Aug 26 at 19:16

I'm assuming by "null probability" you don't mean "impossible" but rather "outside the scope of probabilistic analysis." We rely a lot of probability in the realm of scientific inquiry, but it's not the only way people understand the world and relate to it.

Pascal notwithstanding, most people who believe in God believe for non-probabilistic reasons--personal experience, for instance, or family tradition.

There are also non-probabilistic philosophical reasons for belief in God. One of the most famous is the (neo) Platonic argument. A brief sketch of it would be as follows:

  • It's easy to understand the existence of evil in the world--people pursue their own selfish interests, without regards to others, and random entropy has destructive consequences.
  • It's difficult, however, to understand how true good can exist in the world, and where it would come from.
  • It's possible (according to Plato) to experience true good, but not possible to explain it as a result of the ordinary elements of the world.
  • Therefore true good must have a source outside of the ordinary material world.
  • It makes most sense to attribute a single unified cause to all true good.
  • We call that unified source "God."

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