The present article is an attempt to reassess Aristotelian philosophy by dealing with his axiology. For this purpose first axiology is introduced as a kind of rigorous knowledge and then its relation with the other two types of philosophical knowledge, that is, ontology and epistemology is explained. Then it is illustrated that values such as goodness and beauty are the same as the formal and final causes in axiological explanation of any object and that, at least in nature, the goodness and the final cause of any object are real and thus internal to the nature of the object itself. In contrast, opposite values such as beauty / splendour and good / bad, etc.only exist in relation to us. The claim is that such values do not have objective being. From an epistemological point of view, values are recognized through their formal cause, that is, their universal form. In Aristotelian axiology, the concept oftelos is a fundamental one which shows that Aristotle’s philosophical thoughts constitute a coherent system.
This coherent system enabled Aristotle to claim that values have ontological and epistemological aspects just like object and knowledge. He considers values, objects and knowledge as hierarchical. In other words, every object is granted a status in such a hierarchy of evaluation and this has its roots in the concept oftelos.Aristotle, as a philosopher and as an evaluator, could not be free of evaluation in ontology and epistemology.With the same approach, the article, in its second part will demonstrate that telos in Aristotelian ethics is favourable perfection which human beings are endeavouring to achieve. In this way humans should make sure of the domination of reason, that is, rationality should govern their behaviour.