Which answer would you prefer: 1. “This medicine works better than a placebo”, or: 2. “I estimate the chance that this medicine will work in your case to be 60%”? These two answers reflect a two and a half century lasting dispute between two statistical methods, ‘classical’ (frequentist) and Bayesian. The first is regarded to be more scientific, the latter played a major part in solving many of history’s most important problems, like deciphering coded messages in WO II and predicting disasters. Nowadays many computer programs incorporate Bayes’ theorem to handle experiential knowledge.