Since Martha Nussbaum's (2006) influential inclusion of animals into her version of the capabilities approach (CA), the CA has developed as the most influential theoretical framework for thinking about the extension of justice to nonhumans (for example Schlosberg 2007, Armstrong 2012, Fulfer 2013, Kortetmäki 2017). Yet this discursive paradigm has moved the discussion away from questions of distribution which, as already mentioned, are especially salient in the environmental context. Because it has become so influential, I would like to explain why I do not frame my own account in terms of capabilities – in particular because the CA could provide us an account of wellbeing. Let us begin with a quick survey of the literature that extends justice to nonhumans within this framework (see for a more extensive overview Holland and Linch 2016).

Initially proposed by economist and philosopher Amartya Sen (1999, Nussbaum and Sen 1993), the CA has been extensively developed by Nussbaum (2000, 2006, 2011) and it was quickly adopted by a number of contributors – often referred to as capability theorists. Rather than focusing on the distribution of some material goods themselves, the focus of the CA lies on the functionings – that is, doings and beings – and the capabilities – that is, opportunities or freedoms to achieve these functionings – of humans. The provision of these capabilities, which require different inputs depending on the individual in question, are at the heart of its concern. In other words, capability theorists are concerned with the opportunities that individuals need to live fully functioning – or flourishing – lives. The main departure from Sen's less-specified initial framework was Nussbaum's proposal of a ‘set of human capabilities’; each of which should be enabled for each person to at least a minimum threshold as a matter of justice. She lists the following as what she considers ‘central human capabilities’:

• life

• bodily health

• bodily integrity

• senses, imagination, and thought

• emotions

• practical reason

• affiliation

• other species

• play

• control over one's environment (politically and materially) (2006, pp. 76– 7)

Moreover, central to Nussbaum's version of the CA is that she understands it as a sufficientarian – that is, minimum threshold-based – account of justice within the Rawlsian understanding of political liberalism.