 A triple \(\langle W, \mathbf{A}, \Pr\rangle\) satisfying these three principles is called a (finitely additive) probability space. From these principles it is possible to derive many illuminating theorems. For example, the degree of belief assigned to the contradictory proposition must equal zero. Furthermore, if \(E\) entails \(F,\) then \(\Pr(E)\leq \Pr(F)\). Finally, for any proposition \(E\in\mathbf{A}\) we have that \(0\leq \Pr(E)\leq 1.\)