Socrates believed that there is no gap between ethical knowledge and action because human knowledge causes realization of actions. In addition to criticizing Socrates’ theory, Aristotle considered that the reason of gap between ethical knowledge and action is weakness of free will. Unlike Socrates, Avicenna was not seeing knowledge as the enough condition of action. Also unlike Aristotle, he believed that the effect of desire on free will is not the reason of gap between ethical knowledge and action while he believes that the free will caused by rational knowledge is led to realization of ethical action. To illustrate the gap between ethical knowledge and action, he mentions several internal and external reasons which prevent realization of rational knowledge in human. Therefore, if knowledge is based on weaknesses such as illusion and fantasy and not made of reason, action will not be realized and if it is realized, it will be unethical. In addition, by having rational commentary from verses and narrations, Avicenna provides evidence for his statements and finally he believes that factors such as real worshiping, governance of reason on other powers and realization of certain knowledge will remove the gap between ethical action and knowledge.