How to define and understand the idea of a socially “just society”? This question has many answers; my view is that such a society entitles every member to a set of basic ‘capabilities’: the abilities or powers that a person has to function in society. Philosopher Martha Nussbaum and economist Amartya Sen pioneered this ‘capability approach’ in the 1908s and 1990s. Today, it has become an important alternative to theories which look for the answer in terms of resources (such as money), or subjective views of well-being. But which are these basic capabilities? The longer answer is contained in my version of the capability theory of justice.
I call my version an ‘agency-based’ capability theory, since the foundational thought is this: the most basic thing is the ability to function as an ‘autonomous agent’; a person who is free and able to make her own choices in life. A pre-study for this view was worked out in relation to Nussbaum’s and Alan Gewirth’s theories, in . The full statement of the agency-based capability theory is in my book . A core chapter of that book was published separately as an article . The book contains separate chapters on distributive principles (sufficientarianism and its rivals), on socio-economic capabilities, political capabilities and civil capabilities. N.B. I did more work on autonomous agency, outside the direct context of the capability approach. see under the Theme ‘Freedom, Autonomy and Liberalism’.
I also wrote some general reflections about the capability approach:
- The important question who should select a ‘capability list’, philosophers or rather a democratic public forum, is addressed in [2, 13].
- The question whether a just society should realize functionings for its citizens, instead of capabilities, is the topic of .
- The concept of ‘human dignity’ in the capability approach (in particular Nussbaum’s version of it) is discussed in .
Finally, I extended the capability theory of justice to a few particular topics which interest me:
- the question of private property : do we have a basic capability to hold property? If so, what is its basis and scope?
- financial market regulation : which capabilities are important on financial markets?
- ecological obligations to future generations : do we have them, and if so, can we understand them in capability terms?
- competition law : which capabilities are central to understand competition law’s regulation of markets?
Reviews of other capabilities books are contained in [1, 7].
Publications ‘The Capability Approach to Social Justice’
 ‘New Directions for the Capability Approach: Deliberative Democracy and Republicanism’, in: Res Publica. A Journal of Moral, Legal and Social Philosophy 15 (4)(2009): 421-428. Book review essay of John. M. Alexander, Capabilities and Social Justice. The Political Philosophy of Amartya Sen and Martha Nussbaum (Ashgate, 2008); David A. Crocker, Ethics of Global Development. Agency, Capability, and Deliberative Democracy (Cambridge University Press, 2008). DOI/PDF.
 ‘The Foundations of Capability Theory: Comparing Nussbaum and Gewirth’, co-authored with Marcus Düwell, in: Ethical Theory and Moral Practice 16 (3)(2013): 493-510. DOI/PDF
Reprinted in: Meisch, Simon, Lundershausen, Johannes, Bossert, Leonie, Rockoff, Marcus (eds.). Ethics of Science in the Research for Sustainable Development. (Baden-Baden: Nomos, 2015).
 ‘Human Dignity in the Capability Approach’, in: Marcus Düwell, Jens Braarvig, Roger Brownsword, Dietmar Mieth (eds.), The Cambridge Handbook of Human Dignity (Cambridge: Cambridge University Press, 2014), 240-249. DOI/PDF.
 Review of Freedom, Responsibility and Economics of the Person, by Jérȏme Ballet, Damien Bazin, Jean-Luc Dubois and François-Régis Mahieu, in: Ethics 126 (1)(2015), 196-200. DOI.
 ‘Ecological Rights of Future Generations: A Capability Approach’, in: Gerhard Bos & Marcus Düwell (eds.), Human rights and Sustainability. Moral Responsibilities for the Future (London: Routledge, 2016), 151-165. WEB/PDF.
 Capabilities in a Just Society. A Theory of Navigational Agency (Cambridge University Press, 2018). 264 pp. ISBN 9781108473262. DOI.
 ‘Selecting a List: The Capability Approach’s Achilles Heel’, in: Enrica Chiappero-Martinetti, Siddiq Osmani, Mozaffar Qizilbash (eds.), The Cambridge Handbook of the Capability Approach (Cambridge: Cambridge University Press, 2020), pp. 188-205. DOI/PDF.