DEDUCTION (Lat. deducere, to draw out). A particular aspect of the reasoning process; its counterpart is induction (a.v.I. Many logicians have represented deduction and induction a.s op posed operations, hut a careful attention to the nmvement of thought in shows that such a representation is only partially true. De duction is the recognition of the of a gene•el principle in some partienler en se. For instance, when heat is known In be a mode of motion, the recognition that therefore the laws of motion reculate the phenomena of heat is a deduction. Induction is the reeognition of a parti•ular phenmnenon or group of phenomena as involving a general principle. For instance, when a study of the phenomena of beat to the recognition that they are regulated by the general laws of motion, it is said that an in duction has been made. The difference is one concerning the point of departure in the psycho logical process of reasoning. If we begin with a knowledge of a law, and then recognize this law as obtaining in a special case, we make a deduction. If we begin with some special cases and in these cases recognize a law, we make an induction. In this sense, induction and deduc tion are opposed. processes. But it is clear that to recognize a previously known law as control ling a new phenomenon (deduction) is only the obverse aspect of the recognition of this new phenomenon as involving that definite law (induc tion). Every deduction from a known principle to a new case is logically also at the same time a new induction of the general principle from the new ease taken in conjunction with the old eases. Psychologically, this is not true. That is, often the process of reasoning is psychologi cally nothing more than the process of applying a familiar verbal predicate to a new perception or idea by virtue of some association between the two. But such a predicate cannot be justified, if it is questioned, without an explicit statement of some general principle and an indication that the object perceived or ideated comes this principle; and if it is still further disputed whether the principle holds in this particular case, the only resource left is to make an induc tion from this and other similar cases to the general principle. In other words. induction is involved in every deduction, although, as a matter of psychological fact, it is not generally made with every deduction. Our psychological thought-movements are usually very elliptical when judged from the point of view of logic. but
logic approves of the elliptical processes, if the omitted elements. when restored, help make a. total process which is either inductive or deduc tive, according as it. starts with the particular facts and reaches the general law or rice versa ; and a complete logical process which psychologi cally runs in one direetion can always be psycho logically reversed without prejudice to its logical validity. Wherever an induction is justified, an obverse deduction is justifiable. and rice •ersg. •Transeendental deduction' is a lialinical term in Kant's philosophy, designating a justification of the claim which a priori eonceptiens make of being applicable to any possible objects of experi ence. See LOGIC (where a bibliography is given), and SYLLOMS11.
DEE (Lat. Dera, 0Wolsb Dubr-Duin, water of the goddess. Ir. goddess, Corn. dug, 13ret. doe; conneeted with Lat. dews, !Alb. di'raR. OPruss. dei(ras. Skt. dera. god). A river in Eng land and Wales, draining parts of the counties of Merioneth. Denbigh, Flint, and Shropshire, and the west of Chester (Map; Wales, C 3). it ends in a tidal estuary of the Irish Sea. 13 miles long. and 3 to G miles broad. From the city of Chester. which it almost eneirelen, a canal seven miles long connects the river with the estuary. Its course is 90 miles long, and among its chief trib utaries are the Treveryn and Alwyn. Canals temneet the Dee with the rivers of central Eng land. The aneient BriIons held its waters sacred.
DEE. The name of two rivers in Scotland. The larger rises in five wells, 4000 feet above the sea, in the neighborhood of Ben Macdhui (Slap: Scotland, F 2). After flowing 12 miles south-southeast, it is joined by the Geauley, 129-1 feet above sea-level, tumbles through a narrow chasm, called the Linn of Dee, runs east-north east through Aberdeenshire and a small part of Kincardineshire, and ends in the North Sea at the harbor of Aberdeen. In its course of 90 miles, it receives the Lui, ]Mick, Fcugh, etc. On its banks is Balmoral Castle. The smaller Dee rises near the northern boundary of Kirkcudbright shire (Map: Scotland, D 5). For the first forty miles, it flows southeasterly, then westerly, fall ing into the Solway Firth at Kirkcudbright Bay. It is about 50 miles long and navigable for the last seven miles. The Dee is noted for its sal mon, which are superior in hue and size to those of most rivers in the south of Scotland.