The capability approach evaluates lives, policies and social arrangements by asking a deceptively simple question: what is this person actually able to do and to be? Its two working terms are functionings — the states and activities a person has achieved, such as being nourished, being literate, moving about safely, taking part in the life of the community — and capabilities, the set of alternative combinations of functionings genuinely open to the person. A capability is thus a real freedom, an opportunity set rather than an outcome; the achieved functioning is one point selected from it.
The distinction carries the whole argument. Two people may be equally undernourished, one because there is no food and the other because she is fasting; their functioning is identical, their capability set is not, and any evaluation that cannot separate the destitute from the ascetic is evaluating the wrong thing. Developed by Amartya Sen from the late 1970s and given philosophical scope by Martha Nussbaum, the approach reframes development as the expansion of freedoms rather than the accumulation of goods, and it reframes poverty as capability deprivation rather than low income.
Functionings, capabilities and the informational base
Every theory of justice picks an informational base — the facts it treats as relevant when comparing lives. Sen's contribution was largely a critique of the bases in use, launched in his Tanner Lecture question, equality of what? Utility, income and primary goods each answer differently, and each, he argued, misses something a plausible evaluation cannot afford to miss. The capability approach proposes instead a space of functionings and the freedoms to attain them, and it is deliberately incomplete: it names the space in which comparisons should be made without dictating a single weighting of the dimensions within it.
The critique of income, utility and resources
Against income metrics, Sen observes that money is instrumental. The same rupee income buys mobility for a person who can walk and buys much less for a person with a disability who must hire transport, and the same income buys a different degree of participation in a rich society than in a poor one. Income tells us about means; capability is about ends.
Against utility, the objection is adaptive preferences. Subjective satisfaction is a survivor's device: those long deprived learn to want little, to scale their expectations to their prospects, and to report contentment. Sen's classic illustration is drawn from post-famine morbidity surveys in India, in which populations with objectively poor health, particularly women, reported themselves in good health while better-served populations reported more ailments. A metric built on reported satisfaction rewards resignation and penalises awareness.
Against resourcism — Rawls's index of primary goods — the objection is that equal bundles of resources produce unequal freedom, because human beings differ in what they can do with a bundle. Justice as fairness distributes the means to freedom; the capability approach insists on looking at the freedom itself.
Conversion factors
The mechanism producing that unevenness is the set of conversion factors that translate resources into functionings. Personal factors include age, metabolism, illness and disability. Social factors include public services, discrimination, gender norms, caste, the quality of schooling and the rule of law. Environmental factors include climate, terrain, sanitation infrastructure and the epidemiological setting. A bicycle converts into mobility only where roads exist, where a woman is permitted to ride and where she has learnt to. Conversion factors explain why identical entitlements yield systematically unequal outcomes, and they direct attention away from the individual's endowment towards the institutional and normative environment.
Agency, public reasoning and Nussbaum's list
Sen refuses to legislate a definitive list of valuable capabilities, holding that the selection and weighting of dimensions is a matter for public reasoning by the people concerned. This links the approach to his account of democracy: people are agents who deliberate and act, not patients to be provisioned, and open discussion is itself the procedure by which the relevant freedoms are identified.
Nussbaum diverges here. Grounded in an Aristotelian account of human flourishing and dignity, she specifies ten central capabilities — life, bodily health, bodily integrity, senses and imagination, emotions, practical reason, affiliation, relation to other species, play, and control over one's political and material environment — and treats each as a constitutional threshold below which no citizen should fall, with no trade-offs permitted between them. Her version is a partial theory of political justice; Sen's is a comparative evaluative framework. She also foregrounds gender, care and disability more explicitly than Sen's earlier work.
Operationalisation, and its limits
The best-known partial operationalisation is the Human Development Index, devised by Mahbub ul Haq with Sen's involvement, which combines longevity, education and income. Sen has always described it as a crude device — a counterweight to gross domestic product rather than a measure of capability — and the approach has since generated the Multidimensional Poverty Index, the Gender Inequality Index and a large body of participatory work on dimension selection.
The Indian illustration
Indian deprivation is where the approach earns its keep. High growth has coexisted with poor nutrition, immunisation and schooling outcomes, so income and functioning diverge visibly. Deprivation is patterned by caste, where discrimination in schools, labour and credit markets is a social conversion factor; by gender, where restrictions on mobility, early marriage and intra-household distribution restrict women's freedoms independently of household income; and by region, where Kerala's early achievements in literacy and health at modest income levels, contrasted with faster-growing but less socially provisioned states, became the standing evidence in Drèze and Sen's work that public action on capabilities is not a luxury awaiting prosperity.
Critics reply that the approach is indeterminate — without a list or fixed weights it cannot rank states of affairs; that capability sets are unobservable, so applied work quietly falls back on functionings; that it is individualistic, treating structures only as conversion factors rather than as relations of exploitation; and that Marxist critics find it silent on how inequality is produced rather than merely distributed.
For the UPSC answer
Anchor the answer on the functioning–capability distinction and use it to show why income, utility and primary goods each supply the wrong informational base, naming adaptive preferences as the decisive objection to utility. Bring in the three conversion factors to explain unequal freedom from equal resources, then mark the Sen–Nussbaum divergence over listing versus public reasoning, which examiners reward. Close with Indian material — the growth–nutrition gap, caste and gender as social conversion factors, the Kerala contrast — and register the criticisms of indeterminacy and measurement so the answer reads as evaluation rather than endorsement.
References & further reading
- Sen, A. (1985). Commodities and Capabilities. North-Holland.
- Sen, A. (1999). Development as Freedom. Oxford University Press.
- Nussbaum, M. C. (2000). Women and Human Development: The Capabilities Approach. Cambridge University Press.
- Nussbaum, M. C. (2011). Creating Capabilities: The Human Development Approach. Harvard University Press.
- Drèze, J. and Sen, A. (2013). An Uncertain Glory: India and Its Contradictions. Princeton University Press.
- Robeyns, I. (2017). Wellbeing, Freedom and Social Justice: The Capability Approach Re-Examined. Open Book Publishers.