The Human Function
Aristotle defines the function of humans, so that the best good can be accounted for. To understand how the best good is defined, and how it is related to the function of humans, it is crucial to study the way Aristotle defines the best good.
According to Aristotle, a good is the end result that which everything seeks. Sometimes, the good of one end is the action that helps reach that end, however, in other cases, the product of an action is the good for that action. For example, the good in sleeping is sleeping itself, but the good in reading a bedtime story is sleeping, which is the product of the action, reading. Also, some ends require multiple actions, with each action having its own good. Due to this principle, Aristotle states that there must be one end for every action we do, and that this final end must be the highest good.
Aristotle has always referred to happiness as the highest good; He refers to happiness as "living and doing well" or "living in an excellent manner". Aristotle arrives at this definition for happiness by examining the instances in life where the notions of good arise, and notices that they are all in relation to some sort of activity or function. He furthermore assumes that because their body parts have a function, human beings must have a function as well. Therefore, on this idea, he concludes that in order to find the best good of a human being, he needs to find the function of a human being.
Specifically, Aristotle searches for the activity that is restricted to and characteristic of all humans. The first activity he indicates is living. Living seems to be that activity that is restricted to and characteristic of all...