The Capability Approach: Sen, Nussbaum, and Development as Freedom

When we want to know whether a society is just or whether a life is going well, what should we measure? Income? Wealth? Reported happiness? The capability approach, developed by the Indian economist and philosopher Amartya Sen (b. 1933) and the American philosopher Martha Nussbaum (b. 1947), answers differently: what matters is what people are actually able to be and to do — the real freedoms they have to live the life they have reason to value. It is one of the most influential contributions to political philosophy and normative economics in recent decades, at the frontier between the two disciplines.

1. “Equality of What?” — The Starting Critique

The inaugural question was posed by Sen in a 1979 lecture, “Equality of What?”. Every egalitarian theory of justice wants to equalize something — but what? Sen examines and rejects the two great answers then available.

The first is utilitarianism (and welfarism): assessing well-being by utility — pleasure, satisfaction, or preference fulfillment. Sen objects that this measure is blind to adaptive preferences: those who live in deprivation tend to adjust their desires downward, declaring themselves “satisfied” with very little. To measure justice by subjective satisfaction legitimizes inequality, since the oppressed have learned not to want what is denied them.

The second answer is resourcism — assessing justice by the possession of resources or “primary goods,” as in John Rawls’s theory. Here Sen’s objection is one of conversion: different people convert resources into achieved lives in very unequal ways. A person with a disability, a pregnant woman, or someone living in a harsh climate needs more resources to reach the same level of functioning. Equalizing resources does not equalize real freedoms.

2. Amartya Sen: Functionings, Capabilities, and Freedom

Sen’s alternative shifts the focus to two key concepts. Functionings are a person’s concrete achievements — being well nourished, being healthy, being educated, taking part in public life, having self-respect. A capability is the set of combinations of functionings a person can actually achieve — that is, her real freedom to choose among different ways of living. The distinction is decisive: two people with the same income can have very unequal capabilities, depending on age, gender, disability, or social context.

This perspective grounds his rereading of development. In Development as Freedom (1999), Sen argues that development is not measured by GDP growth but by the expansion of substantive freedoms — income is only a means, not an end. Earlier, in Poverty and Famines (1981), he had shown that great famines rarely stem from an absolute drop in food supply but from the collapse of entitlements — the legal and economic mechanisms by which groups can claim food; hence his famous thesis that mass famines do not occur in functioning democracies with a free press.

In The Idea of Justice (2009), Sen proposes a comparative justice, not a transcendental one: against the Rawlsian ideal of designing perfectly just institutions, he defends a theory aimed at identifying and reducing manifest injustices, inspired by Adam Smith and Condorcet. Consistently with this, Sen refuses to fix a definitive list of capabilities: which capabilities matter and how to weigh them is, for him, a question to be settled by democratic public reasoning, not by the philosopher.

3. Martha Nussbaum: The Central Capabilities List

It is precisely here that Martha Nussbaum diverges productively from Sen. Trained in the Aristotelian tradition, she gives the approach a stronger and more universalist normative grounding, anchored in the notion of human dignity. For Nussbaum, it is possible and necessary to specify a list of ten central capabilities that every just society must secure for each person above a minimum threshold:

1. Life (of normal length); 2. Bodily health; 3. Bodily integrity; 4. Senses, imagination, and thought; 5. Emotions; 6. Practical reason (planning one’s own life); 7. Affiliation (living with and toward others, having the social bases of self-respect); 8. Other species (relation to nature and animals); 9. Play; 10. Control over one’s environment (political and material).

Two of these — practical reason and affiliation — are “architectonic”: they organize and pervade all the others. The list is meant to be a partial specification of justice, a set of social minimums compatible with different conceptions of the good life.

Nussbaum also deepens two themes. On the emotions, she holds that they are not irrational impulses but evaluative judgments (appraisals) charged with cognitive content — fear, compassion, and indignation contain assessments of what matters, so that an ethics without emotions is blind. And she extends the approach beyond the human: in Frontiers of Justice (2006), she applies it to disability, national belonging, and non-human animals, which also have capabilities to be respected.

4. Sen or Nussbaum? The Open List and the Specified List

The difference between the two defines the approach’s internal debate. Sen keeps the list open: he emphasizes freedom, agency, and the democratic process of choosing the relevant capabilities, avoiding the risk of imposing a conception of the good life from above. Nussbaum defends the specified list: without a defined minimum content, she argues, the approach has no way to ground concrete claims of justice or to protect the most vulnerable. The risk of the first path is indeterminacy; that of the second, paternalism. The tension is less a flaw than the theoretical engine of the field.

5. Applications and Critiques

The approach has had notable practical impact. Sen collaborated with the economist Mahbub ul Haq in creating the Human Development Index (HDI), adopted by the United Nations from 1990 onward, which combines income, education, and life expectancy — a concrete attempt to measure development by something more than GDP.

The critiques cluster on three fronts. Some point to an excessive individualism: by focusing on each person’s capabilities, the approach is said to struggle to thematize structures, classes, and relations of power. There is the indexing problem: how to weigh and compare heterogeneous capabilities (health versus political participation) without a common metric? And there is the charge of paternalism, directed above all at Nussbaum: who has the authority to fix the universal list without reimposing a particular conception of flourishing? These controversies have not weakened the approach — on the contrary, they have made it one of the liveliest fields of contemporary political philosophy and welfare economics.

Essential Readings

• Amartya Sen, “Equality of What?” (1979); Development as Freedom (1999); The Idea of Justice (2009).
• Amartya Sen, Poverty and Famines (1981); Inequality Reexamined (1992).
• Martha Nussbaum, Women and Human Development (2000); Frontiers of Justice (2006); Creating Capabilities (2011).
• Martha Nussbaum, Upheavals of Thought: The Intelligence of Emotions (2001) — for the theory of emotions.

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