Is Sen's capability approach an adequate basis for considering human development?

Sen's capability approach (SCA) has supported valuable work on Human Development (HD). It has brought attention to a much wider range of information on people's freedoms and well-being than in most earlier economic planning; but it also has troubling features and requires modification and enrichment. This paper first identifies the approach's components, the contributions of the HD Reports, and the doubts about whether SCA has a sufficient conception of human personhood to sustain work on HD beyond finding indices superior to GDP. It then examines SCA's central concepts. The concepts of capability and functioning lead us to consider both possibilities and outcomes, but their definition and use has been confusing. Besides Sen's opportunity concept of 'capability' we must distinguish skills and potentials; and distinguish levels and types of 'functioning'. To understand both consumerism and what can motivate and drive more humanly fulfilling development, we must elaborate different aspects and sources of 'well-being' and the content and requirements of 'agency', more than in Sen's chosen strategy. SCA's priority category of opportunity-capability must be read as a measure of personal advantage relevant in many public policy situations, rather than as a theory of well-being; and its concept of freedom must be partnered by concepts of reason and need.