Probability theory is the body of knowledge that enables us to reason formally about uncertain events. The populist view of probability is the so-called frequentist approach whereby the probability of an uncertain event a, written P(a), is defined by the frequency of that event based on previous observations. For example, 48.78% of all babies born in the UK (2007-2011) are girls; suppose then that we are interested in the event a: ‘a randomly selected baby is a girl’. According to the frequentist approach P(a)=0.4878.