I think itโs highly subjective and intuition-based for most people. For a very basic moral claim X, you would just ask: โHow likely does X seem to me?โ And then the probability that occurs directly to you is what you go with.
You might consider arguments for or against, but ultimately just pick a number directly for many claims. For other claims, you might derive them from others, e.g. multiplying (conditional) probabilities for each premise in an argument to get the probability of the conclusion (or a lower bound on it).
I think itโs highly subjective and intuition-based for most people. For a very basic moral claim X, you would just ask: โHow likely does X seem to me?โ And then the probability that occurs directly to you is what you go with.
You might consider arguments for or against, but ultimately just pick a number directly for many claims. For other claims, you might derive them from others, e.g. multiplying (conditional) probabilities for each premise in an argument to get the probability of the conclusion (or a lower bound on it).