ANALOGY, a term originally Greek. and which signifies an agreement or correspond ence in certain respects between things in other respects different. Euclid employed it to signify proportion, or the equality of ratios, and it has retained this sense in mathematics; but it is a term little used in the exact sciences, and of very frequent use in every other department of knowledge and of human affairs. In grammar we speak of the A. of language, i.e., the correspondence of a word or phrase with the genius of the language, as learned from the manner in which its words and phrases are ordinarily formed. A., in fact, supposes a rule inferred from observation of instances, and upon the application of which, in other instances not precisely, but in some respects, similar, we venture, with more or less confidence, according to the degree of ascertained similarity, and according to the extent of observation from which our knowledge of the rule has been derived. The opposite to A. is anomaly (Gr. irregularity); and this term is used not only in gram mar, but with reference to objects of natural history which in any respect are exceptions to the ordinary rule of their class or kind. In the progress of science, analogies have been discovered pervading all nature, and upon which conclusions are often based with great confidence and safety. Reasoning from A. indeed warrants only probable conclu• sions; but the probability may become of a very high degree, and in the affairs of life we Must often act upon conclusions thus attained. Reasoning from A., however, requires much caution in the reasoner. Yet even when its conclusions are very uncer tain, they often serve to guide inquiry and lead to discovery. Many of the most brilliant
discoveries recently made in natural science were the result of investigations thus directed. Where the proper evidence of truth is of another kind, arguments from A. are often of great use for the removal of objections. It is thus that they are employed by bishop Butler in his A. of Religion, Natural and Revealed, to the Constitution and Course of Nature. In law, reasoning from A. iniist'often, to a certain extent, be admitted in the application of statutes to particular cases. Upon similar reasoning, the practice of medicine very much depends. To discover the meaning composition, it is also often necessary; the sense of the author in a passage somewhat obscure being in some measure determined according to passages in which he has expressed himself more clearly. The application of this rule to the interpretation of Scripture is a point of dif ference between Protestants and Roman Catholics, the latter insisting upon the interpre. tation of difficult passages by ecclesiastical tradition and authority. The extension of it to the whole Scriptures, however, depends upon the admission of their inspiration; but this, when fully admitted, warrants a more confident use of analogical reasoning than in the case of the works, or even of a single work, of an uninspired author. Protestant theologians have very generally employed, with reference to this rule of interpretation, the phrase " A. of faith," deriving it from Rom. xii. 6; but the meaning of the expres sion in that verse is disputed. However, the reality of an A. of faith, and the right of reasoning from it, are not affedted by any criticism on that verse.