ABSTRACT and ABSTRACTION. The term abstract is sometimes used as a noun to denote a summary or digest of a document. Such an abstract is usually obtained by selecting what is essential and omitting the rest. Speaking generally, the process of abstraction is usually a process of selection of some part or aspect of a complex whole, and of consequent neglect of the rest. The result of such a process of "withdrawal" (in the twofold sense of selecting a part and neglecting the rest) is commonly described as abstract.
In logic, e.g., abstract terms are distinguished from concrete terms, the latter denote objects consisting of a whole complex of attributes and standing in various relations, whereas the former designate some quality or relation isolated or abstracted from its concrete context. For instance, "motor" and "relative" are con crete terms, whereas "motion" and "relationship" are abstract terms. But there are degrees of abstraction—the selection may be less or more restricted, and the consequent neglect more or less extensive. This may be readily seen if one passes in review such a series of terms as, say, "the horse that won the Derby in 1927," "race-horse," "horse," "quadruped," "animal," "life." Of these terms only the last would be called abstract, but really all the terms in the series except the first are obtained by abstraction. In fact all general terms, or common nouns, are the result of abstraction. That is why some of the earlier logicians and psy chologists applied the epithet abstract to what are now usually called general concrete terms. It is just a matter of convenience and convention that only the more abstract terms are now called abstract, the less abstract terms being called general.
In the past too much stress used to be laid on the negative side of abstraction, that is, on the mere neglect of certain parts or aspects of the concrete whole. It is now realized more fully that the process is mainly positive in character. It is a process of posi tive selection, not merely one of omission, though of course it involves omission. The relative stress on the positive and the negative sides of the process of abstraction really varies consider ably. When the process is merely spontaneous, or not deliberate, the negative character of abstraction is probably more prominent; when it is deliberate, that is, a process of voluntary attention, the positive phase is the more marked.
Abstraction is of great importance for all real knowledge, es pecially for science and philosophy. The aim of all scientific knowledge is the discovery of laws expressing the relation or correlation between various aspects of reality, such as mass and gravitation, volume and pressure, or temperature and volume; and it is by processes of abstraction that these phases of reality are isolated and followed up. (A. Wo.)