 The precise chronology of al-Fārābī’s works is difficult to establish. He wrote treatises devoted to the explanation of Plato and Aristotle, commentaries and paraphrases of Aristotle’s works, and other treatises where he develops his own philosophical thought unifying his metaphysical and cosmological views with his psychology, and even with his political philosophy. His views concerning psychological and epistemological matters appear in several places within his treatises. Hence, it is necessary to consider several works where he clarifies and completes his thoughts on the matter. The Principles of Existing Things, also known as The Political Regime (Kitāb al-siyāsa al-madaniyya), and The Principles and Opinions of the People of the Virtuous City (Mabādi’ ārā’ ahl al-madīnah al-fāḍilah), are some of al-Fārābī’s major works where he deals with psychological topics such as the nature of the soul, its cognitive capacities, and the doctrine of the intellect. Furthermore, there is another important treatise where al-Fārābī directly deals with the intellective faculty, namely, The Treatise on the Intellect (Risālah fi’l-‘aql). This work shows signs of the influence of Aristotle’s doctrine of the soul and its interpretation by Alexander of Aphrodisias. In fact, M. Geoffroy (2002: 191–231) contends that al-Fārābī probably never read a complete translation of Aristotle’s On the Soul but knew it through Alexander’s treatises, mainly the On the Intellect. Al-Fārābī addresses epistemological topics such as the understanding of scientific knowledge and the nature of demonstration and certitude mainly in the Book of Demonstration (Kitāb al-burhān) and the Book on the Conditions of Certitude (Kitāb Šara’iṭ al-yaqīn). In order to cover the diversity of psychological and epistemological matters in al-Fārābī’s works, this article is divided as follows: