Aristotle evaluated the subject-predicate discourse where a subject exemplifies a universal notion in different predication types. A subject is a particular example of a universal notion that a predicate creates. Aristotle suggested two different prediction types: essential and accidental (the qualities something has).
The former indicates that the subject’s predicate cannot change without the subject losing its very nature – the predication is essential to the existence of the subject. Meanwhile, accidental predication described the ability of the subject to change its characteristic predicate and remain itself. Thus, essential predication or a “said-of” relation indicates a subject belonging to a larger kind or group, while accidental predication or a “said-in” is a quality that a subject happens to have.
Aristotle then created a “four-fold division” into the categories of essential, accidental, both, or neither. A range of features can characterize any subject: when described, it becomes a primary substance, with the characteristics being secondary substances. Aristotle argues that because of the all-encompassing nature of the essential predicates, they have ontological primacy – if a concept of a cat did not exist, a cat named Becky would not either.
Ultimately, Aristotle concludes that the “soul is not separable from the body” and separates the souls into a nested hierarchy: nutritive, perceptual, and rational. Ibn Sina or Avicenna questions the framework, invoking his analysis of the soul and separating it into bodily faculties, rational-practical and rational-theoretical.
Unlike Aristotle, Avicenna states that souls may be imprinted with universal forms and acquire the form of whatever concept they apprehended. This approach seems more grounded than Aristotle’s ‘size-fits all idea of a soul being universal that is not subject to change. Both concepts hinge on complexity and individuality, but Aristotle concludes that no soul is unique, which seems self-contradict.