Education for sustainable development (ESD) and higher education for sustainable development (HESD) are complex, multidisciplinary fields of enquiry, drawing on concepts and terms from different disciplines and languages. Although the fields are advancing in their acceptability within educational systems worldwide, they are currently struggling to achieve sought-after graduate and societal outcomes such as environmentally-responsible or sustainability-focussed-citizenship. The research described in this article explores the possibility that miscommunication or misunderstanding of basic concepts within these fields is contributing to slow progress towards their objectives. We used a philosophical hermeneutic analysis to explore how the terms 'competence' and 'capability' are used within selected ESD/HESD papers. We identify substantial internal contradictions and inconsistencies with respect to differences between learners' abilities and their willingness to perform these abilities, and to the educational context in which these outcomes are sought. We emphasise the importance of linking educational objectives with pedagogical approaches to teaching and assessment.