IDENTITY (ML. identitas, sameness, from identicus, same, from Lat. idem, same). THE LAW OF. The principle that in any train of thought, such as a syllogism, there must be running through all the differences of contents a oneness of meaning, in which is found the consistency of the phrase of thought. This definition leads to the consideration of the dispute about the mean ing of identity. Some have maintained that it is undifferentiated sameness, and that the differences which are found among similar things are accre tions of unlikenesses around the core of sameness. Others have maintained that no two objects of consciousness are exactly alike, and that identity is not undifferentiated likeness, but a likeness in difference or a differentiated likeness. The debate centres around the conception of philosophical atomism. It is possible by abstraction to obtain an idea of some quality which is the element of likeness between several objects, and which can he thought as itself undifferentiated. Take color, for instance. In all the different colors, such as red, green, and yellow, can we find by abstraction some one element which is undifferentiatedly alike? Suppose we say that it is that quality of the visual sensation which is due to the stimulus of (relatively) homogeneous light vibrations. (See Corm.) Even the answer does not seeure undifferentiated likeness. That quality thus pro duced is not one quality, but it is "at least 160 spectral color qualities" (Titchener), each irredu cible to any other. But even these are not sharp ly defined against each other. Although we can
not distinguish all the differences, there is every reason to suppose that there are differences which. though they affect our experience, we are not attentively aware of. There is a continuum of color. (See CONTINUITY. LAW oF.) If so. there is no undifferential sameness of color. although there is a sameness which we recognized in the differences. There is a oneness in all the reds, which oneness we cannot isolate, although ire can recognize. So there is a oneness in all color. uni solable hut distinguishable and recognizable. What is true of color is true of everything else. Atomistic explanation of color is false to fact. Undifferentiated sameness is not offered by ex perience. Hence an identity might be defined as an unisolable hut distinguishable oneness of attri butes in objects which at the same time might present a multiplicity within the same attributes. For the atomistie views of identity, consult James, Principles of Psychology (Ne• York, 1893) : for the opposite view, Bradley. Principles of Logic. books i., ii. (London. 1883) ; also the discussion between James and Bradley in Mind, new series, vol. ii. (London. 1893) ; Bradley. Appearance and Reality (see index for pertinent passages) (Lon don, 1897) ; llosanquet. Logic (see index for pertinent passages) (London. 1888) : Fullerton. Sameness and Identity (Philadelphia. 1890) ; also the authorities referred to under LOGIC; KNOWL EDGE, THEORY OF,