In his work On Interpretation, he maintained that the concept of "universal" is apt to be predicated of many and that singular is not. For instance, man is a universal while Callias is a singular. The philosopher distinguished highest genera like animal and species like man but he maintained that both are predicated of individual men. This was considered part of an approach to the principle of things, which adheres to the criterion that what is most universal is also most real. Consider for example a particular oak tree. This is a member of a species and it has much in common with other oak trees, past, present and future. Its universal, its oakness, is a part of it. A biologist can study oak trees and learn about oakness and more generally the intelligible order within the sensible world. Accordingly, Aristotle was more confident than Plato about coming to know the sensible world; he was a prototypical empiricist and a founder of induction. Aristotle was a new, moderate sort of realist about universals.
In his work On Interpretation, he maintained that the concept of "universal" is apt to be predicated of many an,d that singular is not. For instance, man is a universal while Callias is a singular. The philosopher distinguished highest genera like animal and species like man but he maintained that both are predicated of individual men. This was considered part of an approach to the principle of things, which adheres to the criterion that what is most universal is also most real. Consider for example a particular oak tree. This is a member of a species and it has much in common with other oak trees, past present and future. Its universal, its oakness, is a part of it. A biologist can study oak trees and learn about oakness and more generally the intelligible order within the sensible world. Accordingly, Aristotle was more confident than Plato about coming to know the sensible world; he was a prototypical empiricist and a founder of induction. Aristotle was a new, moderate sort of realist about universals.