Aristotle, the greatest of the Ancient Greek philosophers, taught that moral reasoning was based upon the telos, or a thing’s end or purpose. The telos tells us why it exists. Once we know the purpose of a thing, we can evaluate it. You cannot say if a thing is good or bad if you have no understanding of its purpose. For instance, if the pocket watch is too heavy to be comfortably carried and is a bit too large to fit in most pockets and does not keep time well, we would say that it is a bad watch. From these facts, we can form an evaluative judgment, but only if we know its telos or purpose.