Although we can trace some aspects of the capability approach back to, among others, Aristotle, Adam Smith, and Karl Marx (see Nussbaum 1988, 1992, 2020; Sen 1993a, 1999: 14, 24; Walsh 2000), it is economist-philosopher Amartya Sen who pioneered the approach and philosopher Martha Nussbaum and a growing number of other scholars across the humanities and the social sciences who have significantly developed it. The capability approach purports that freedom to achieve well-being is a matter of what people are able to do and to be, and thus the kind of life they are effectively able to lead.