 Most people use the term ‘aql to describe the capacity that enables a person to discern which deeds are virtuous and which are not by means of deliberation. This first sense is very close to Aristotle’s conception of prudence. Similarly, Islamic theologians use this term to refer to those actions that are accepted or repudiated in general or by the majority. More important for our purposes in this article are the different senses of the term in the Aristotelian corpus. According to al-Fārābī, in Posterior Analytics 2.19, ‘aql is understood as a faculty of the soul by means of which certainty about necessary, true, and universal premises is attained. Premises of this kind are not arrived at by means of syllogisms, but are present in the subject in a prior way, either by nature or without one being aware of how these premises were acquired. Hence, this faculty is some part of the soul by which humans have access to the first principles of the theoretical sciences. I shall refer to this use of the term in detail in the final section of this article (al-Fārābī LI: 5–9; OI: 69–70).