For the baseline, “underlying” probability of the oracle’s request being declined. Roughly speaking, if you have never seen X happen, it does not mean that X will never happen (=has a probability of zero).
This assumes you’re a passive observer, by the way—if you are actively making a decision whether to accept or decline the request you can’t apply Bayesian probabilities to your own actions.
Your prior for what?
For the baseline, “underlying” probability of the oracle’s request being declined. Roughly speaking, if you have never seen X happen, it does not mean that X will never happen (=has a probability of zero).
This assumes you’re a passive observer, by the way—if you are actively making a decision whether to accept or decline the request you can’t apply Bayesian probabilities to your own actions.