The course introduces students to the philosophies that have both generated architectural designs since the early 20th century, as well as those which allowed criticism of prevailing work. These will be placed in the context of wider social, political and economic concerns that marked the 20th Century, and the start of the 21st. Lectures will introduce the main trends of thought of the period, which include evolutionism, Marxism, existentialism, structuralism and environmentalism. Case studies of the works of key architectural writers are undertaken in seminars. The course will enable students to categorize architectural works from the period according to the philosophy or ideas they embody, and to critically appreciate the strengths and limitations of those ideas.