Theories in Social Anthropology I: Classical Evolutionism (Tylor, Morgan, Frazer, Maine, McLennan), the Three Schools of Diffusionism, Boas's Historical Particularism, Malinowski's Functionalism, and the Structural-Functionalism of Radcliffe-Brown, Firth, Fortes, Eggan and Parsons

The evolutionists of the second half of the nineteenth century asked how human institutions had come to be as they were, and answered that all societies pass through the same stages of development in the same order, from the simple to the complex, because the human mind is everywhere the same ("psychic unity") and responds to similar conditions in similar ways; contemporary "primitive" peoples therefore showed the earlier stages through which civilised peoples had passed. Their method was the comparative method — arranging customs gathered from travellers, missionaries and administrators from all over the world into a sequence — and the doctrine of survivals, customs that persist beyond the stage in which they had a use and so reveal the past. Edward Burnett Tylor (Researches into the Early History of Mankind, 1865; Primitive Culture, 1871) defined culture, divided history into savagery, barbarism and civilisation, made animism the origin of religion, and in 1889 ("On a Method of Investigating the Development of Institutions") used statistical "adhesions" between customs across 350 societies — to which Francis Galton objected that similarities might come from diffusion rather than independent development ("Galton's problem"). Lewis Henry Morgan, a lawyer of Rochester who studied the Iroquois (League of the Iroquois, 1851) and collected kinship terminologies worldwide (Systems of Consanguinity and Affinity, 1871), set out in Ancient Society (1877) seven "ethnical periods" — Lower, Middle and Upper Savagery, Lower, Middle and Upper Barbarism, and Civilisation — each begun by a technological invention (fire and fishing; the bow and arrow; pottery; the domestication of animals in the Old World and irrigated maize in the New; iron smelting; the phonetic alphabet and writing), with a parallel evolution of the family from promiscuity and the consanguine and punaluan families to the syndyasmian, the patriarchal and the monogamian, and of property and government; Engels built The Origin of the Family, Private Property and the State (1884) on it. James George Frazer (the syllabus's "Fraser"), the most famous of the armchair anthropologists, never did fieldwork; in The Golden Bough (1890; twelve volumes by 1915) he traced the evolution of thought from magic through religion to science, and he compiled Totemism and Exogamy (1910). Henry Sumner Maine, a jurist who served in India, compared Roman, Hindu and European law in Ancient Law (1861) and Village Communities in the East and West (1871), argued for the priority of the patriarchal family and traced the movement "from status to contract". John Ferguson McLennan, a Scottish lawyer, argued in Primitive Marriage (1865) — where he coined "exogamy" and "endogamy" — that early humans lived in promiscuous hordes, that female infanticide caused a shortage of women and hence polyandry and marriage by capture (surviving as mock capture in wedding rites), that kinship was first traced through women, and he introduced totemism (1869–70). J.J. Bachofen (Das Mutterrecht, 1861) had proposed an original matriarchy. The school's weaknesses were evident by 1900: its stages were conjectural history, its sequences unilinear, its values ethnocentric, and its evidence uncritically gathered; the reaction took two forms, diffusionism and Boas's historical particularism, and after Malinowski the field replaced the armchair.

The diffusionists answered the evolutionists that humans are not very inventive, that important inventions were made once or a few times, and that cultural similarities are better explained by borrowing and migration (diffusion) than by parallel independent development. They divided into three schools. The British or "heliocentric" school held the most extreme view: Grafton Elliot Smith, an anatomist who had studied Egyptian mummies (The Ancient Egyptians, 1911; The Migrations of Early Culture, 1915; Human History, 1930), argued that civilisation — agriculture, metallurgy, mummification, megaliths, sun worship and kingship — arose once, in Egypt about 4000 BCE, and spread across the world with the "Children of the Sun", the title of W.J. Perry's book of 1923; W.H.R. Rivers, turning from evolutionism, explained Melanesian society by successive migrations in The History of Melanesian Society (1914). The German-Austrian or Kulturkreis ("culture circle") school was more systematic. Friedrich Ratzel (Anthropogeographie, 1882–91) set out the criterion of form — similar objects without a functional reason for similarity must be historically connected; Leo Frobenius introduced the Kulturkreis (1898); Fritz Graebner (Methode der Ethnologie, 1911) formalised the criteria of form (quality) and quantity — the more elements two cultures share, the likelier their connection — and later of continuity; and Father Wilhelm Schmidt of the Society of the Divine Word in Vienna, founder of the journal Anthropos (1906), arranged the world's cultures into a small number of culture circles spreading in sequence — primitive (hunter-gatherers), primary, secondary and tertiary — and argued in Der Ursprung der Gottesidee (twelve volumes, 1912–55) for a primitive monotheism (Urmonotheismus) among the simplest peoples. The American school was the most cautious and the most empirical. It limited diffusion to demonstrable historical contact within regions, mapped traits by culture areas — geographical regions sharing a common set of culture traits, an idea introduced by Otis Mason (1895) and systematised by Clark Wissler (The American Indian, 1917; Man and Culture, 1923) — and in Wissler's "age-area" hypothesis inferred that traits found over the widest area around a culture centre are the oldest, since they have had longest to spread; Alfred Kroeber (Cultural and Natural Areas of Native North America, 1939) refined the culture area with the "culture climax" of greatest intensity, and Edward Sapir (Time Perspective in Aboriginal American Culture, 1916) set out methods for inferring history from distributions. Diffusionism declined because its historical reconstructions could not be tested and its view of cultures as assemblages of traits ignored how the parts fit together — the point on which functionalism was built — but diffusion itself remains one of the mechanisms of culture change, and the culture area is still in use.

Franz Boas (1858–1942), trained in physics and geography in Germany, turned to anthropology after his winter among the Inuit of Baffin Island (1883–84) and built American anthropology at Columbia University from 1899. In "The Limitations of the Comparative Method of Anthropology" (1896) he attacked the evolutionists' method: similar customs can arise from different causes and by different historical paths (the principle of convergence), so they cannot be lined up into universal stages until the history of each has been established. Each culture is the product of its own particular history — its environment, its borrowings, its internal developments — and must be studied in its own terms, inductively, by long fieldwork, collecting texts in the native language, before any generalisation is attempted. Marvin Harris later named this position "historical particularism" (The Rise of Anthropological Theory, 1968). Boas's other contributions were as large. He founded cultural relativism, the demand to understand each culture by its own values; he attacked racial determinism with his measurements of immigrants' children in New York (1910–12), whose head form changed with environment, and with The Mind of Primitive Man (1911), which denied any hierarchy of mental capacity between races; he established the four-field discipline and the American Anthropological Association (1902); he made language central, directing the Handbook of American Indian Languages (1911); and his long collaboration with George Hunt produced the Kwakiutl texts from which the potlatch is known. His students became American anthropology: Alfred Kroeber, Robert Lowie, Edward Sapir, Alexander Goldenweiser, Paul Radin, Ruth Benedict, Margaret Mead, Melville Herskovits, Ella Deloria and Zora Neale Hurston. The criticism of historical particularism is that its caution became a refusal to generalise, leaving a mass of ethnographic detail without theory; the neo-evolutionists (Unit VIII, next chapter) and Harris were its sharpest critics.

Bronislaw Malinowski (1884–1942), a Pole trained in physics and philosophy at Kraków who came to anthropology through Frazer's Golden Bough and studied under Seligman and Westermarck at the London School of Economics, created both the modern method of fieldwork and the theory of functionalism. His Trobriand monographs — Argonauts of the Western Pacific (1922), Crime and Custom in Savage Society (1926), Sex and Repression in Savage Society (1927), The Sexual Life of Savages (1929) and Coral Gardens and Their Magic (1935) — showed every institution working with every other in the living whole of a society. His theory, set out in A Scientific Theory of Culture (published in 1944, after his death), is biological and psychological: culture exists to satisfy human needs. There are basic needs — metabolism, reproduction, bodily comforts, safety, movement, growth and health — each met by a cultural response (commissariat, kinship, shelter, protection, activities, training, hygiene); derived or instrumental needs created by culture itself — economic organisation, social control, education, political organisation; and integrative or synthetic needs — knowledge, magic, religion, art and play — that give the whole its coherence. The unit of analysis is the institution, analysed by its charter, personnel, norms, material apparatus, activities and function. The function of any cultural element is the part it plays in satisfying needs, and every element has one — which his critics called the axiom of "universal functionalism". Malinowski's legacy is the intensive, participant fieldwork of a year or more in the native language that became the discipline's hallmark, the insistence on the native's point of view, and a generation of students at the LSE — Raymond Firth, Edward Evans-Pritchard, Isaac Schapera, Audrey Richards, Hortense Powdermaker, Meyer Fortes, Edmund Leach, Jomo Kenyatta. The criticisms are that functionalism reduced culture to biology and psychology, could not explain change or conflict, treated every trait as useful, and studied societies as if they had no history or colonial context.

A.R. Radcliffe-Brown (1881–1955), a student of Rivers and Haddon at Cambridge who worked in the Andaman Islands (1906–08; The Andaman Islanders, 1922) and in Western Australia, and taught at Cape Town, Sydney, Chicago and Oxford, built structural-functionalism on Durkheim's sociology rather than on psychology. He aimed at "a natural science of society" (his 1937 Chicago lectures, published in 1957) that would compare societies to discover general laws. Social structure is "the network of actually existing social relations" between persons, persisting as a structural form while individuals come and go; social organisation is the arrangement of activities. Function, by analogy with an organism, is "the contribution which a partial activity makes to the total activity of which it is a part" — the part a custom plays in maintaining the structure — so that a society is a functional unity, and customs are explained by the structure they sustain, not by their history (which he dismissed as conjectural) or by individual needs. His essays, collected in Structure and Function in Primitive Society (1952), analysed the mother's brother in South Africa (1924), joking relationships (1940), totemism, sanctions and the kinship systems of Australia and Africa (African Systems of Kinship and Marriage, 1950). Raymond Firth (1901–2002), Malinowski's successor at the LSE and the ethnographer of Tikopia (We, the Tikopia, 1936), distinguished social structure — the enduring framework of relations — from social organisation — the "systematic ordering of social relations by acts of choice and decision" within it (Elements of Social Organization, 1951), so bringing choice and change into the model. Meyer Fortes (1906–83), the ethnographer of the Tallensi of Ghana (The Dynamics of Clanship, 1945; The Web of Kinship, 1949), developed descent group theory ("The Structure of Unilineal Descent Groups", 1953), with the concept of complementary filiation and the developmental cycle of domestic groups, and edited African Political Systems (1940) with Evans-Pritchard. Fred Eggan (1906–91), Radcliffe-Brown's student at Chicago, combined structural-functional analysis with the American concern for history in Social Organization of the Western Pueblos (1950) and proposed the method of "controlled comparison" (1954) — comparing societies within one region with a shared history, so that differences can be related to specific causes. Talcott Parsons (1902–79), the Harvard sociologist, gave structural-functionalism its general theory of action in The Structure of Social Action (1937) and The Social System (1951): every social system must meet four functional prerequisites — adaptation, goal attainment, integration and latency (pattern maintenance), the AGIL scheme — and orientations to action are described by five pairs of "pattern variables" (affectivity–affective neutrality, diffuseness–specificity, particularism–universalism, ascription–achievement, collectivity–self orientation). The criticisms of structural-functionalism were those of functionalism — the neglect of change, conflict, history and the individual — and Evans-Pritchard's 1950 Marett lecture, which called social anthropology a kind of historiography rather than a natural science, opened the turn to meaning.