126 THE AMERICAN JOURNAL OF SOCIOLOGY
plant kingdom needs a name. We therefore call it " tree." When we say " tree," we connote the complicated process of elimination, of which the above is merely a hint. Each of the words descriptive of tree, as distinguished from other subjects of the plant kingdom, is a word that stands for an exclu- sion of some plant trait which does not belong to the plant tree.
Scientific judgments are comparisons of abstractions. Errors of judgment are very largely the result of thinking about "plant" what is true only of "tree " and of assuming for "tree" whatever is the case with "plant." As we rise from relatively simple to more and more complex concepts, this lia- bility is increased. In social science the danger is seldom absent, and few are the reasoning processes which entirely escape it. That old scapegoat, " the economic man," has borne ten thousand sins of this class."
Accordingly, abstraction is the chief working means for the construction of general ideas. Abstraction rests, however, upon analysis. The facts with reference to which general ideas are to be derived must first be separated into distinct components, before the process of elimination can begin. The scientific significance of abstraction rests partly on its own inherent value, and partly and chiefly upon its importance as component and assistant of other logical processes. One of the most important achievements of the analytical method is success in bringing out into distinct relief, above the mass of details that make up a complex fact, certain elements, to be held isolated for a while, in order that they may be subjected to close examination.
There is another decided advantage possible in combining analysis and abstraction, viz., following the analysis many sorts of abstractions may be made by the free choice of the investigator, and the one abstraction may be made to complement the others. (This is illustrated in the case of "health, wealth, sociability, knowledge, beauty, righteousness.")
Abstraction is of two primary sorts, viz.: (l) isolating (abstraction), (2) generalizing (abstraction).' The former of these is the more primary. To it the analytic method always leads in the first place. It is also presupposed in every generalizing abstraction. It does not follow, however, that the two are regularly consecutive gradations of development. On the contrary, iso- lating abstraction has its own independent value. In many cases it is impos- sible to advance beyond this form of abstraction. In others, generalizing abstraction, so far as it is possible, adds relatively little of importance. The essence of isolating abstraction consists in arbitrarily contemplating certain components of a complex object of knowledge as though they were entirely separated from other components.^
The crusades, e. g., manifested economic, ethnic, social, aesthetic, intellec-
' Fi</f American Journal of Sociology, March, 1897, pp. 744-5 ; review of Godkin.
'An illustration of (i) is Spencer's (a) sustaining system, (b) transporting system, (c) regulating system ; of (2) Giddings' "consciousness of kind"
3 E. g.. General Walker's abstraction of economics from ethics, etc., ('. e., contem-
