The comparative method is the systematic juxtaposition of two or more cases — societies, regions, institutions, communities or periods — in order to discover which features occur together, which vary independently, and therefore which can plausibly be treated as causes of which. Sociologists cannot randomise villages, assign religions or withhold industrialisation from a control group. What they can do is find cases that already differ in the relevant respect and hold as much else constant as the world allows. Comparison is thus not an optional embellishment on description; it is the discipline's structural substitute for the experiment, and the logic of the two is the same even though the control is achieved by selection rather than by manipulation.
The method also performs a second, less formal service. Comparison denaturalises the familiar. Arrangements that appear inevitable inside one society — the conjugal household, the wage contract, the individual as the unit of rights — become visible as variables once a society organised otherwise is set beside them. Much of what sociology knows about its own categories it learned by finding places where they do not apply.
Durkheim's rules
Émile Durkheim made comparison the centre of sociological method. Since the sociologist has no laboratory, he argued in The Rules of Sociological Method, the only available proof is indirect experiment, and its instrument is the method of concomitant variation — the demonstration that two phenomena vary together across a series of cases in a manner too regular to be accidental. Durkheim preferred this to crude agreement or difference because concomitant variation does not require that all other conditions be identical, only that the covariation be systematic and that a plausible mechanism connect the terms.
He added rules of procedure. Compare only phenomena of the same social species, since institutions belonging to societies of different types are not commensurable. Establish the normal form of an institution for that species before diagnosing pathology. And prefer comparison of successive states of the same society, or of closely related societies, over promiscuous ranging across the ethnographic record. His practice followed the precept: Suicide compares Protestant with Catholic regions, married with unmarried, peacetime with political crisis, treating the covariation of rates as the evidence for integration and regulation as causes.
Mill's methods and the two basic designs
Durkheim was adapting John Stuart Mill. Mill's method of agreement examines cases that share an outcome and searches for the single antecedent they also share; his method of difference examines cases alike in most respects but differing in outcome, and searches for the antecedent present in one and absent in the other; the joint method combines them, and concomitant variation extends the logic to matters of degree. Mill himself doubted that these instruments could work on societies, because social causation is plural and conjunctural — the same outcome may arise by several routes.
Modern comparative design restates the pair as strategies of case selection. Przeworski and Teune distinguished the most-similar systems design, which takes cases alike in context — neighbouring Indian states, Scandinavian welfare regimes — so that the few remaining differences carry the explanatory weight, from the most-different systems design, which takes cases sharing an outcome despite maximal contextual variation, so that whatever they still share stands out. Along another axis, comparison may be cross-national, cross-cultural (comparing communities rather than states, as in anthropological sampling) or diachronic, comparing the same unit across periods — the form Comte called historical and Radcliffe-Brown urged as the anthropologist's discipline against speculative evolutionism.
Weber's comparative sociology of religion
Max Weber used comparison to a different end. His question was why rational bourgeois capitalism arose in the modern West and nowhere else, and his answer required not correlations across many cases but the construction of contrasts. In The Protestant Ethic and the Spirit of Capitalism and then across the studies of Confucianism and Taoism, Hinduism and Buddhism, and ancient Judaism, he asked what each civilisation possessed and what it lacked: China had literacy, cities, markets and a rational bureaucracy but a this-worldly ethic of adjustment; India had rigorous rationality in thought but, in Weber's reading, an ethic bound to caste duty and rebirth that turned salvation away from methodical worldly labour. The method is comparison by ideal type — an intentionally one-sided construct against which cases are measured — and its purpose is to identify the historically unique conjuncture rather than a general law. Weber's account of Indian religion has been substantially criticised for relying on textual sources and understating mercantile and artisanal practice, but the comparative architecture remains a model.
Comparison within India
India is itself a comparative field, and its sociologists have exploited this. Irawati Karve compared kinship across northern, southern, central and eastern zones to show that a single civilisation sustains structurally opposed systems of marriage and descent. M. N. Srinivas built the concept of the dominant caste by comparing villages in which numerical strength, landholding and ritual rank combined differently. Comparison of states — Kerala against Uttar Pradesh on literacy, fertility and women's status, or Punjab against Bihar on agrarian transformation — has become the standard way of arguing that public action and social structure, not aggregate income alone, drive social development. Because these units share a constitution, a currency and much law, they approximate a most-similar design more closely than most cross-national work can.
The problems
Four difficulties recur. The first is small N and many variables — the cases available are few and the candidate causes many, so several rival explanations remain compatible with the evidence; Ragin's response was to formalise comparison as the analysis of configurations rather than of independent variables. The second is conceptual non-equivalence: caste, class, household, religion and even unemployment do not mean the same thing across settings, so a comparison of identically named measures may compare nothing. The third is Galton's problem, Francis Galton's objection that societies are not independent trials, since similarities may result from diffusion, conquest or shared ancestry rather than from functional necessity — a correlation across colonised societies may record the colonising power, not a sociological law. The fourth is ethnocentrism in the categories themselves: when the framework is derived from one civilisation and others are scored on their distance from it, comparison degenerates into ranking, which is the standing charge against evolutionary and modernisation typologies.
For the UPSC answer
Establish at the outset that comparison substitutes for the experiment by selection rather than manipulation. Give Mill the logic of agreement and difference, Durkheim the method of concomitant variation with his rules on social species and the normal, and Weber the comparison of civilisations through ideal types. Name the designs — most-similar and most-different, cross-national, cross-cultural, diachronic — and illustrate with Indian material, either Karve's kinship zones or the Kerala and Uttar Pradesh contrast. Reserve the last paragraph for the four limitations, and be sure to name Galton's problem and conceptual non-equivalence, since these separate an informed answer from a generic one.
References & further reading
- Mill, J. S. (1843). A System of Logic, Ratiocinative and Inductive. London: John W. Parker.
- Durkheim, É. (1895). The Rules of Sociological Method.
- Radcliffe-Brown, A. R. (1951). The Comparative Method in Social Anthropology. Journal of the Royal Anthropological Institute, 81.
- Przeworski, A. and Teune, H. (1970). The Logic of Comparative Social Inquiry. New York: Wiley.
- Smelser, N. J. (1976). Comparative Methods in the Social Sciences. Englewood Cliffs: Prentice-Hall.
- Ragin, C. C. (1987). The Comparative Method: Moving Beyond Qualitative and Quantitative Strategies. University of California Press.