Building on its core of central concepts and normative commitments, the capability approach can be developed into more specific capability theories. As Robeyns (2017, chapter 1) argues, some specifications are necessary to make, such as what the purpose of the theory is, what capabilities or functionings are normatively relevant, and whether to focus on capabilities or functionings. Other specifications are optional in the sense that whether we need them depends on the particular capability theory we are developing, including how to weigh different capabilities against each other and what other normative concerns that the theory should take into consideration. In this section, we explain some of the choices that need to or can be made when developing a capability theory.