Ibn Sina's Philosophical and Medical Ideas on Relation between Faculty of Rationality (Intellection) and Brain

Ibn Sina considers faculty of rationality as an abstract faculty which in performing its duty does not depend on any organ of body.Justifying his view, he uses several arguments concerning immateriality of human soul. Meanwhile he refers to the need of this faculty to three other faculties namely: sense, imagination and thinking which all have bodily organs. Moreover, in some cases, he says that disorder in faculty of rationality results from a weakness, fatigue or corruption in brain. Furthermore, as a physician, he regards head's and brain's disease as some causes which may disorder or stop rational thinking and he prescribes necessary medicines to cure them.In this paper first we will discuss Ibn Sina's philosophical and medical viewpoints concerning the faculty of rationality, then we will explain the relation between brain and faculty of rationality and analyse the positive or negative role of body organs – especially brain – in the act or this faculty. Finaly we will discuss how Ibn Sina's apparently different views in this relation, can be summed up.