Aristotle took issue with Plato’s account of knowledge, because it consisted of too much sugar and not enough vitamins and minerals. Although Aristotle agreed with Plato that the object of human knowledge must be the universal, he could not accept Plato’s theory of the transcendent forms. Plato denied that knowledge of physical objects in themselves was possible, because these things were constantly changing, and knowledge needed to be stable and grounded. Therefore, Plato separated the natures of physical objects from them and assigned their natures to a transcendent realm.

It is only in this separated condition through illuminated reason that one could come to know the universal forms or essences of things. It was only to the degree that the natural objects “participated” in or “imitated” the ideal forms that the objects were in any sense real. Aristotle objected to this notion and asserted that one could not actually separate the formal principle of any physical object from that object. The consequence would be no knowledge at all. Therefore, Aristotle guided our minds from the transcendent to the immanent as the necessary doorway to knowledge.

Aristotle argued that we do not need to separate the nature of an object from the object itself in order to understand the object’s formal principle. By insisting on this separation, we conflate how we know a thing with what the thing is. We come to know what a thing is purely by mental abstraction without any need of actually amputating the form from the object itself. This does not mean, however, that the essence of an individual thing exists only in the mind of the knower; it means that the mind apprehends the formal (universal) principle and abstracts it from the individual by observing what is similar or common among the particulars of its kind. 

Therefore, our attention must initially focus upon the objects of experience if we are to attain knowledge. Empirical study of natural objects must guide the process of exact thinking about such objects. Furthermore, the notion of the universal is the result of this exercise of the mind. However, though the universal exists as a mental abstraction and not a transcendent form, the formal principle or essence defined by the universal is nonetheless a real element of and concretely adheres within the individual itself. “Clearly, then,” stated Aristotle, “definition is the formula of the essence, and essence belongs to substances....” (Metaphysics 1031a, 13-15).

In other words, to say that all members of a class exhibit humanness is to articulate the mentally abstracted universal; to say a particular member within the class is human is to articulate that individual’s real essence or form existent within it. Thus, the essence or form of any object is the abstract universal actually at work in the physical particular. The insight one achieves by penetrating into the essence of a thing through this process of mental abstraction of the formal principle and consequent perception of the universal, Aristotle called knowledge.

Aristotle’s view of knowledge paved the way for natural science, that is, the study of nature and natural things as such, because he offered an account of natural objects that established their real ontological status. No longer were they an illusion per Parmenides or quasi-real per Plato, but fully real in themselves and the legitimate objects of scientific inquiry. Hence, for Aristotle, physics became the first among the natural sciences. The method of physics involved moving from the general to the specific. For instance, one might begin with the most general category of substance such as matter, and then continue to organic matter, to animal, to two-footed animal, and finally to rational animal or man. Each step would represent increasing specificity in knowing that particular thing with which we are dealing, not progressive awareness of different levels of reality.

Thus, Aristotle saw his method as truly scientific, and stood opposed to Plato’s theory that knowledge is the recollection of innate but forgotten perfect ideas once known in a heavenly preembodied existence. For Aristotle, the inquiry into the form and the essence of physical objects began and ended within the natural world. However, Aristotle was by no means a philosophical materialist who reduced all of  being to the physical. Though physics may have been the first science in a practical sense, Aristotle did not consider it the highest science. We will consider this highest science known as "Metaphysics" in our next post.

Blessings,

Arnie Gentile