As we have seen, the first stage or step in the process of Thought is that called Perception, which we have considered in the preceding chapter. Perception, as we have seen, is the process by which we gain our first knowledge of the external world as reported to us by the channels of sense. The Perceptive faculties interpret the material which is presented to us by the senses. Following upon Perception we find the processes resulting from the exercise of the group of faculties which are classified under the general head of Understanding.
Understanding is the faculty, or faculties, of the mind by means of which we intelligently examine and compare the various _percepts_, either separating them by analysis, or else combining them by synthesis, or both, and thus securing our general ideas, principles, laws, classes, etc. There are several sub-phases of Understanding which are known to psychologists and logicians as: (1) Abstraction; (2) Conception or Generalization; (3) Judgment, and (4) Reasoning, respectively. In this chapter we shall consider the first of these sub-phases or steps of Understanding, which is known as “Abstraction.”
Abstraction is that faculty of the mind by which we abstract or “draw off,” and then consider apart, the particular qualities, properties, or attributes of an object, and thus are able to consider _them_ as “things” or objects of thought. In order to form _concepts_ or general ideas, from our _percepts_ or particular ideas, we must consider and examine two common points or qualities which go to make up _differences and resemblances_. The special examination or consideration of these common points or qualities result in the exercise of Abstraction. In the process of Abstraction we mentally “draw away” a quality of an object and then consider it as a distinct object of thought. Thus in considering a flower we may _abstract_ its qualities of fragrance, color, shape, etc., and think of these as things independent of the flower itself from which they were derived. We think of _redness_, _fragrance_, etc., not only in connection with the particular flower but as _general qualities_. Thus the qualities of redness, sweetness, hardness, softness, etc., lead us to the abstract terms, _red_, _sweet_, _hard_, _soft_, _etc._ In the same way courage, cowardice, virtue, vice, love, hate, etc., are abstract terms. No one ever saw one of these things–they are known only in connection with objects, or else as “abstract terms” in the processes of Thought. They may be known as qualities, and expressed as predicates; or they may be considered as abstract things and expressed as nouns.
In the general process of Abstraction we first draw off and set aside all the qualities which are _not common_ to the general class under consideration, for the concept or general idea must comprise only the qualities common to its class. Thus in the case of the general idea of horse, size and color must be abstracted as non-essentials, for horses are of various colors and sizes. But on the other hand, there are certain qualities which _are common to all horses_, and these must be abstracted and used in making up the concept or general idea.
So, you see, in general Abstraction we form two classes: (1) the unlike and not-general qualities; and (2) the like or common qualities. As Halleck says: “In the process of Abstraction, we draw our attention away from a mass of confusing details, unimportant at the time, and attend only to qualities common to the class. Abstraction is little else than centering the power of attention on some qualities to the exclusion of others…. While we are forming concepts, we abstract or draw off certain qualities, either to leave them out of view or to consider them by themselves. Our dictionaries contain such words as purity, whiteness, sweetness, industry, courage, etc. No one ever touched, tasted, smelled, heard, or saw purity or courage. We do not, therefore, gain our knowledge of these through the senses. We have seen pure persons, pure snow, pure honey; we have breathed pure air, tasted pure coffee. From all these different objects we have abstracted the only like quality, the quality of being pure. We then say we have an idea of _purity_, and that idea is an abstract one. It exists only in the mind which formed it. No one ever saw _whiteness_. He may have seen white clouds, snow, cloth, blossoms, houses, paper, horses, but he never saw _whiteness_ by itself. He simply abstracted that quality from various white objects.”
In Abstraction we may either (1) abstract a quality and set it aside and apart from the other qualities under consideration, as being non-essential and not necessary; or we may (2) abstract a quality and hold it in the mind as essential and necessary for the concept which we are forming. Likewise, we may abstract (1) all the qualities of an object _except one_, and set them aside that we may consider the _one_ quality by itself; or we may (2) abstract the one particular quality and consider it to the exclusion of all its associated qualities. In all of these aspects we have the same underlying process of considering a quality apart from its object, and apart from its associated qualities. The mind more commonly operates in the direction of abstracting one quality and viewing it apart from object and associated qualities.