 Aristotle, an apprentice of Plato, was another early and influential philosopher, who argued that ethical knowledge is not "certain" knowledge (such as metaphysics and epistemology), but is "general" knowledge.Because it is not a theoretical discipline, a person had to study and practice in order to become "good"; thus if the person were to become virtuous, he could not simply study what virtue "is", he had to "be" virtuous, via virtuous activities.To do this, Aristotle established what is virtuous