Similarity and Analogy as a Leading Feature of Enquiry

Abstract

Similarity is partial identity: the characteristics of similar objects are in part identical and in part different. Not a single observable mark of one object need coincide with a mark of the other, and yet the marks of the one may be interrelated in exactly the same way as those of the other. Jevons² calls analogy a more deep-seated similarity; one might say, an abstract similarity. Analogy may in some circumstances remain quite concealed from direct sense observations and reveal itself only through comparison of conceptual interconnections between the marks of one object with the corresponding connections in the other. Maxwell³ not only defines analogy but also underlines those features of it that are most important for scientific enquiry, when he describes analogy as that partial similarity between the laws in one field and those in another, so that each illustrates the other. However, we shall see that Maxwell’s approach is not different from ours. Hoppe⁴ regards the concept of analogy as superfluous, since as with similarity in general it is merely a matter of conceptual agreement of certain marks in the objects between which analogy is found. Although this is correct, there are good grounds for taking analogy as a special case of similarity and distinguishing it from the general concept. Above all, it is the enquirer into nature who is driven to this view, since taking notice of analogies greatly furthers his work.

Reproduced from Ostwald, Annalen der Naturphilosophie, Vol. I, with amplifications.