 Some authors interpret probabilities as generalized truth values (Reichenbach 1949, Leblanc 1983). According to this view, probability logic is just a particular kind of many-valued logic, and probabilistic validity boils down to ‘truth preservation’: truth (i.e. probability 1) carries over from the premises to the conclusion. Other logicians, such as Tarski (1936) and Adams (1998, 15), have noted that probabilities cannot be seen as generalized truth values, because probability functions are not ‘extensional’; for example, \(P(\phi\wedge\psi)\) cannot be expressed as a function of \(P(\phi)\) and \(P(\psi)\). More discussion on this topic can be found in Hailperin (1984).