When we speak of the White House or of Khrushchev or of the bomb dropped at Hiroshima, our words are specific and designate the concrete. They identify things or persons or events, and have only one application. Such specific, concrete words are, of course, indispensable. At the same time, if we were limited to such words, we would suffer a handicap that might well be fatal to the development of knowledge. We could make remarks about one or a few specific and concrete items, but the more of them we tried to comment about, the more of our time we would have to spend simply in naming the items. No remark about human beings in general would be possible without naming all of them individually.
We handle this problem by an obvious but fundamentally important process. That is, we note likes and unlikes, similarities and differences; we see patterns or groups or classes or combinations of items. And then we name or otherwise identify what seem to belong together, and talk about the items named collectively. Thus we can speak of men and women without naming them individually; and we can speak of states, politicians, voters, purposes, and so on. We can think in terms of classes or categories or types rather than in terms of the multitude of separate items involved.
Four words are important in describing and understanding this process and the benefits derived. They are abstraction, classification, concept, and generalization. Our purpose now is to explore their meaning and significance, and the interrelationships among them.