Abstraction is an epistemological term that refers to that act of the intellect which “abstracts” intelligibility from beings in the world. To obtain knowledge of something in the world by abstraction is to come to a knowledge of a universal essence from a particular object of experience. For example, when I look at a dog, my mind has the ability to know the abstract concept of dog from seeing a particular dog. The formation of this concept in my mind is that metaphysical act we call abstraction.
In this act, the mind has the ability to understand an object in different ways. One way the mind understands is by understanding an individual being as a whole. This is called a total abstraction. An example of this is when the mind abstracts “human” from an individual man. The mind, however, may also grasp one aspect of a man; perhaps the color of his skin, or the size of his head. After the act of abstraction, in the acts of judgment and reasoning, we may use these different abstractions to scientifically study various beings in the world.
In addition to the mind’s ability to perform a total abstraction or to grasp a particular aspect of a being, we may also distinguish between three levels of abstraction. These levels of abstraction correspond to the distance the abstraction is from the sensible world. For example, I have many ways to describe different aspects of a given being. I may grasp a thing’s materiality. I may also consider a being’s quantity. If I consider (scientifically) a thing’s biological classification, I am relying on the first level of abstraction. If I choose to quantify several natures or accidental properties of a thing, I am considering a thing according to second level abstraction. Scientifically, the discipline that makes use of second level abstractions is mathematics.
When one considers a thing materially, one is operating on the first level of abstraction. On this level, our mind grasps not only the abstract nature of a thing, but the concrete individual. First level abstraction concerns the concrete individual. Concepts formed at this level still contain properties of the sensible object. It may be tempting to say that this is the only thing the mind grasps about a being, but that would not be true.
Second level abstractions, or formal abstractions, take from another aspect of the sensible. In addition to understanding an objects sensible qualities, the mind also grasps quantity from the object known. We understand that there is a single individual we are speaking to rather than twenty individuals. The mind may consider a things extension in space or its continuous quantity. From this level of abstraction, we may group things according to their nature or we may quantify some beings accidental qualities. It is important to keep in mind that at this stage in the knowing process, the mind abstracts quantity from the object of experience rather than imposing quantity on a thing.
Finally, the level of abstraction most ignored by contemporary philosophers is that of third level abstraction. Third level abstraction considers a being as a being. On this level, we are not concerned with the size, shape or weight of a being. Nor are we concerned about the classification of this being into genus and species. Third level abstraction deals with a being completely removed from its sensible qualities. It is here that we find the basis for the study of metaphysics.
