Sensation and Reason

Aristotle said that the senses provide informa- tion about the environment: sight, hearing, taste, touch, and smell. Unlike earlier philosophers (such as Empedocles and Democritus), Aristotle did not believe objects sent off tiny copies of themselves (eidola). Rather, he thought that perception was explained by the motion of objects that stimulate one of the senses. The movement of environmen- tal objects creates movements through different media, and each of the senses is maximally sensitive to movements in a certain medium. For example, seeing results from the movement of light caused by an object in relation to the sensory abilities of the eye. In this way, Aristotle explained how we could actually sense environmental objects without those objects sending off physical copies of themselves. Unlike Plato, Aristotle believed we could generally trust our senses to yield an accurate representation of the environment.

Common Sense and Reason. As important as sensory information was to Aristotle, it was only the first step in acquiring knowledge. In other words, sensory experience is a necessary, but not a sufficient, ele- ment in the attainment of knowledge. In the first place, each sensory system provides isolated information become an oak tree, but it cannot become a frog or an olive tree. In other words, the purpose, or entele- chy, of an acorn is to become an oak tree. Nature is characterized by the change and motion that occurs as objects are slowly transformed from their poten- tialities to their actualities—that is, as objects move toward their final causes or purposes, such as when an acorn becomes an oak tree. Aristotle also saw the final cause, or purpose, of something as its essence.