mode (from Latin modus, ‘way’, ‘fashion’), a term used in many senses in philosophy. In Aristotelian logic, it refers either to the arrangement of universal, particular, affirmative, or negative propositions within a syllogism, only certain of which are valid (this is often translated as ‘mood’ in English), or to the property a proposition has by virtue of which it is necessary or contingent, possible or impossible. In Scholastic metaphysics, it was often used in a not altogether technical sense to mean that which characterizes a thing and distinguishes it from others. Micraelius (Lexicon philosophicum, 1653) writes that ‘a mode does not compose a thing, but distinguishes it and makes it determinate.’ It was also used in the context of the modal distinction in the theory of distinctions to designate the distinction that holds between a substance and its modes or between two modes of a single substance. The term ‘mode’ also appears in the technical vocabulary of medieval speculative grammar in connection with the notions of modes of signifying (modi significandi), modes of understanding (modi intelligendi), and modes of being (modi essendi). The term ‘mode’ became especially important in the seventeenth century, when Descartes, Spinoza, and Locke each took it up, giving it three somewhat different special meanings within their respective systems. Descartes makes ‘mode’ a central notion in his metaphysics in his Principia philosophiae. For Descartes, each substance is characterized by a principal attribute, thought for mind and extension for body. Modes, then, are particular ways of being extended or thinking, i.e., particular sizes, shapes, etc., or particular thoughts, properties (in the broad sense) that individual things (substances) have. In this way, ‘mode’ occupies the role in Descartes’s philosophy that ‘accident’ does in Aristotelian philosophy. But for Descartes, each mode must be connected with the principal attribute of a substance, a way of being extended or a way of thinking, whereas for the Aristotelian, accidents may or may not be connected with the essence of the substance in which they inhere. Like Descartes, Spinoza recognizes three basic metaphysical terms, ‘substance,’ ‘attribute’, and ‘mode’. Recalling Descartes, he defines ‘mode’ as ‘the affections of a substance, or that which is in another, and which is also conceived through another’ (Ethics I). But for Spinoza, there is only one substance, which has all possible attributes. This makes it somewhat difficult to determine exactly what Spinoza means by ‘modes’, whether they are to be construed as being in some sense ‘properties’ of God, the one infinite substance, or whether they are to be construed more broadly as simply individual things that depend for their existence on God, just as Cartesian modes depend on Cartesian substance. Spinoza also introduces somewhat obscure distinctions between infinite and finite modes, and between immediate and mediate infinite modes.
Locke uses ‘mode’ in a way that evidently derives from Descartes’s usage, but that also differs from it. For Locke, modes are ‘such complex Ideas, which however compounded, contain not in them the supposition of subsisting by themselves, but are considered as Dependences on, or Affections of Substances’ (Essay II). Modes are thus ideas that represent to us the complex properties of things, ideas derived from what Locke calls the simple ideas that come to us from experience. Locke distinguishes between simple modes like number, space, and infinity, which are supposed to be constructed by compounding the same idea many times, and mixed modes like obligation or theft, which are supposed to be compounded of many simple ideas of different sorts.
See also DESCARTES, LOCKE, METAPHYSICS , PROPERTY , SPINOZ. D.Garb.