This article compares the approaches to practical philosophy of the two most significant Muslim philosophers of the classical period, al-Farabi (d. 950) and Ibn Sina (d. 1037). Initially, I will examine their classification of the practical sciences and show their formal differences, and then question whether these differences point to a fundamental disagreement about the source of practical knowledge. One of my conclusions is that al-Farabi clearly separated the intellectual and independent concept of practical philosophy from the religious sciences, whereas Ibn Sina's standpoint is religious-based, dependent, and partially covered by Islamic jurisprudence. As the latter emphasizes these various points in separate passages about the source...