Marshall McLuhan

McLuhan's central claim — 'the medium is the message' — is a theory of technology's origin as much as a theory of communication. By 'medium' he means any extension of a human faculty: the wheel extends the foot, clothing extends the skin, the electric circuit extends the central nervous system. The 'message' of each technology is not what it carries but what it does to the ratio of the senses and to social organization. The alphabet, by reducing speech to phonetic symbols, created a visual, linear, sequential mode of thought that made individualism, nationalism, and scientific abstraction possible. The electric medium, which operates at the speed of light and is non-sequential, reverses that tendency — hence his famous paradox of the 'global village', simultaneous and tribal.

For McLuhan, technologies have a trajectory independent of the intentions of their inventors, because they operate at the level of the nervous system before any conscious processing occurs. The origin of a technology's effects, in his framework, is the human body — specifically the particular faculty being extended — and the reorganization it imposes on all other faculties when it is amplified. He identified four laws that govern any technology or medium, which he called the 'tetrad': what does it enhance? what does it render obsolete? what does it retrieve from the past? and what does it reverse into when pushed to its limit? These four questions constitute a kind of morphology of technical artifacts that locates the origin of each technology in the sensory and cognitive economy it disturbs.