By rejecting Plato’s Theory of Forms, Aristotle clears the way for his empirical approach, which emphasizes observation first and abstract reasoning second. Aristotle received his philosophical education at Plato’s Academy, so it is natural that he would feel obliged to justify at length why he departs from the doctrines of his teacher. He provides detailed arguments against many of Plato’s doctrines in almost all of his major works, focusing in particular on the Theory of Forms.

In Aristotle’s view, the Theory of Forms is essentially an assertion of the superiority of universals over particulars. Plato argues that particular instances of, say, beauty or justice exist only because they participate in the universal Form of Beauty or Justice. On the contrary, Aristotle argues that universal concepts of beauty and justice derive from the instances of beauty and justice in this world. We only arrive at a conception of beauty by observing particular instances of beauty, and the universal quality of beauty has no existence beyond this conception that we build from particular instances. By saying that the particulars come first and the universals come after, Aristotle places emphasis on the importance of observing the details of this world, which stands as one of the important moments in the development of the scientific method.