Avicenna's Theory of Action

According to Avicenna’s picture of the principles of volitional acts, humans perceive the pleasure (utility/goodness) or pain (harm/badness) of a thing. Then they develop a desire or an interest to that thing, on the basis of which a will arises, and then the nerves or the agential faculties inherent in the muscles bring about muscular movements and hereby the act is done. This is a general picture the components of which can be gathered from different works of Avicenna, but these components are not prima facie—or even in fact—consistent. One important feature of Avicenna’s theory of action is that all the three of external faculties, (estimation) vahemah, and intellect (aql) play their role in the perception of pleasures, but each perceives a particular kind of pleasure in a particular manner. Moreover, Avicenna’s argument for the existence of volition and the role of estimation and practical reason in actions seems problematic.