In my previous blog entry I gave a quick introduction to Bayes’ theorem. In this blog entry I’ll show how Bayes’ theorem can be used in the service of theism.
When I put forth for the moral argument, I that argued that “If God does not exist, then objective morality does not exist” was likely true, and that it seems unlikely on atheism that objective morality exists. Another way to put it: “The probability that objective morality exists given that atheism is true is low.” With the conception of God I’m using, the existence of God entails that objective morality exists (God is morally good independently of human opinion), such that “The probability that objective morality exists given that God exists” is 100%. So we can construct a form of the moral argument that uses Bayes’ theorem and the following symbols:
- H is the hypothesis that God exists.
- ~H is the proposition that God does not exist (and thus that atheism is true).
- E is the evidence of objective morality.
- Pr(E|H) is the probability that objective morality exists given that God exists.
- Pr(E|~H) is the probability that objective morality exists given that atheism is true.
- Pr(E|~H) = 0.25
- Pr(H) = 0.5
- Pr(~H) = 0.5
- Pr(E|H) = 1