In this article the author attempts to present Aristotle's argumentation against the universal fatalism, which is, in the view of fatalists, a necessary consequence of the universal application of the principle of bivalence to the contradictory propositions about the future state of affairs. This problem Aristotle examines in his De Interpretatione ch. 9, wich is the main issue here. Presentation flows trough three steps: 1. Aristotle's formulation of the problem, 2. Aristotle's presentation and criticism of the logical determinism and, finally, 3. Aristotle's libertarian solution of the problem. Author points out that through the history of interpretation of the problem there are different views. These views differ not only concerning the spirit of Aristotle's text or his final solution, but concerning the way in which he refuted the universal validity of the logical determinism and fatalism.