ABSTRACT
Probability is an important element in clinical medicine, especially when research employs randomised clinical trials. Hence, some familiarity with it and the statistical techniques that are derived from it are important. The probability theory is philosophically rich. The logical interpretation is the least well understood outside mathematics and philosophy. Its fundamental tenet is that probability is a logical (mathematical) relation among propositions. Four broad interpretations of the probability calculus have been explicated over the last century: logical, frequency, subjective and propensity. Most of the writings on the interpretation of probability have focused on the difference between frequency and subjectivist interpretations. The chapter draws an analogy with geometry, using the history of geometry to draw out what is meant by, "The key observation is that on this interpretation the mathematical calculus does not contain any specification of its connection to the empirical world.".
