This article employs an analytical-descriptive and, to a certain extent, a comparative methodology to examine the prominent views of Muslim philosophers regarding practical reason and its origins as rooted in Aristotle's works. Then, a novel explanation of Avicenna's opinion regarding the cognitive or stimulating nature of practical reason based on his principles of psychology is presented and briefly contrasted with Farabi's opinion. The role of practical reason in Avicennian ethics is subsequently examined in light of the dual meanings of practical wisdom in his works. The findings of this study indicate that Avicenna, based on his foundations in the separation of faculties, never attributed a single action to two faculties in an essential and primary manner. Consequently, the perception of reasonable generalities is an essential act of theoretical reason, and the perception of particulars is an essential act of the animal soul's faculties. Therefore, Avicenna does not consider practical reason to be a cognitive faculty. The essential act of practical reason is the inference of the beauty or ugliness, and goodness or badness of partial acts as evidenced by perceptual faculties. This function of practical reason has a negative preliminary role for practical wisdom as science and a positive, stimulating role for practical wisdom as a virtue. However, one should not overlook the other significant function of practical reason in producing moral propositions generally accepted by the common people.