This article reports a rhetorical discourse analysis of learner perspectives on language diversity in a contemporary South African high school. Based on four group discussions with Grade 12 isiXhosa, Afrikaans and Engli~h-speaking learners, the analysis traces two interrelated clusters of argument. In the first, a liberal discourse of individual freedom and human rights is mobilised to argue against a language order where languages are made compulsory, or forced upon people. We show that this argument was employed inconsistently: it only extended to languages other than English. To understand how this dilemmatic use of liberal ideas was justified, we trace a second line of argument. This is the construction of English as a universal language and, consequently as neutral, necessary and unifying; a language of 'rational choice' for all South Africans. Based on these arguments, language diversity -or the formal recognition and empowerment of languages other than English -was problematised as both violating individual rights of choice and a public order characterised by the mutual and universal understanding afforded by the universality of English. Supporting English-only practices in the school was thus presented as itself a liberal gesture, allowing not only the continued racialisation of isiXhosa, but also a rhetoric of racial blame: isiXhosa speakers, when they use their language in public, were blamed for instigating racial tension and misunderstanding in the school.