Aristotle on Perfect and Imperfect Sense Activities

Aristotle seems to think that a sense such as sight or taste can work imperfectly in certain conditions, for example, when it is dark, or the perceiver is ill. This article addresses the question of how he can account for imperfect sense activities as well as for perfect sense activities. The answer proposed is that Aristotle’s account is based on a certain understanding of the sense as a capacity: he defines the sense as a capacity for exercising a perfect (i.e., successful) activity rather than any activity whether perfect or not. In developing this answer, the article shows how Aristotle incorporates the conditions for a perfect activity into the definition of a sense and how he explains an imperfect activity by reference to a failure to satisfy some of these conditions. This discussion also helps to understand the reasons why Aristotle might think that a sense is not infallible about its proper sensible objects in all conditions.