British linguist, teacher, and proponent of neo-Firthian theory who viewed language basically as a social phenomenon.

Halliday obtained his B.A. in Chinese language and literature from the University of London and then did postgraduate work in linguistics, first at Peking University and later at the University of Cambridge, from which he obtained his Ph.D. in 1955.

In his early work, known as “scale and category linguistics,” Halliday devised four categories (unit, structure, class, and system) and three scales (rank, exponence, and delicacy) to describe language. He also did work on intonation (Intonation and Grammar in British English, 1967) and on discourse analysis (Cohesion in English, 1976). His later theory, sometimes called systemic linguistics, was that language has three functions: ideational, interpersonal, and textual.