> It's not something that happens randomly, people choose to.
In Bayesian analysis, probability does not refer to the long-term frequency but instead to the subjective credence given to the event. Otherwise the probability of any one-off event would be undefinable. Therefore it follows that you need to have a prior over possible hypothesis in order to update your beliefs systematically according to the laws of probability theory. If it were known that Hikaru had cheated in the past, but typically does not, we might use a different prior (e.g. a Laplacian prior in this case); if we knew cheating to be dependent on some other measurable variable (e.g. the emotional state of the player), we would incorporate this into our evidence.
In Bayesian analysis, probability does not refer to the long-term frequency but instead to the subjective credence given to the event. Otherwise the probability of any one-off event would be undefinable. Therefore it follows that you need to have a prior over possible hypothesis in order to update your beliefs systematically according to the laws of probability theory. If it were known that Hikaru had cheated in the past, but typically does not, we might use a different prior (e.g. a Laplacian prior in this case); if we knew cheating to be dependent on some other measurable variable (e.g. the emotional state of the player), we would incorporate this into our evidence.