This article deals with the position of Aristotle and Diodorus Cronus about logical necessity. It shows that Aristotle rejects logical necessity, by denying the universal application of the principle of bivalence, in order to preserve the value of deliberation. Secondly, it shows that Diodorus is led to fatalism due to his defense, based upon his modal notions, of the thesis according to which there are types of events logically contingent, but that still all particular events of the world are necessary.El presente artículo se ocupa de las postura de Aristóteles y Diodoro Crono en torno a la necesidad lógica. Allí se muestra que Aristóteles rechaza la necesidad lógica, mediante la negación de la aplicación universal del principio de bivalen...