Abstract :
The author expresses agreement with the original paper, by M. Laviolette and J.W. Seaman (ibid., p.4-15), saying that probability is the only satisfactory measure of one´s personal uncertainty about the world. The reason for this emphatic statement is that there exist several axiom systems that produce, as theorems, the rules of probability. In particular, the author criticises the use of fuzzy logic as an alternative.<>