Relations (philosophy)

Relations are ways in which things, the relata, stand to each other. Relations are in many ways similar to properties in that both characterize the things they apply to. Properties are sometimes treated as a special case of relations involving only one relatum. In philosophy (especially metaphysics), theories of relations are typically introduced to account for repetitions of how several things stand to each other. The concept of relation has a long and complicated history. One of the interests for the Greek philosophers lay in the number of ways in which a particular thing might be described, and the establishment of a relation between one thing and another was one of these. A second interest lay in the difference between these relations and the things themselves. This was to culminate in the view that the things in themselves could not be known except through their relations. Debates similar to these continue into modern philosophy and include further investigations into types of relation and whether relations exist only in the mind or the real world or both. An understanding of types of relation is important to an understanding of relations between many things including those between people, communities and the wider world. Most of these are complex relations but of the simpler, analytical relations out of which they are formed there are sometimes held to be three types, although opinion on the number may differ. The three types are (1) spatial relations, which include geometry and number, (2) relations of cause and effect, and (3) the classificatory relations of similarity and difference that underlie knowledge. Similar classifications have been suggested in the sciences, mathematics, and the arts. An important distinction is between internal and external relations. A relation is internal if it is fully determined by the features of its relata. For example, an apple and a tomato stand in the internal relation of similarity to each other because they are both red.