In this article, we examine ways in which critics of liberalism come to adopt, without acknowledgement, ‘liberal’ forms of public reason in responding to homogenising tendencies of fundamentalist doctrines. We focus on the divergent approaches of John Gray and Slavoj Žižek, arguing that the former upholds a comprehensive form of liberalism, while the latter upholds a political form popular among policy makers who endorse a ‘fundamentalism’/‘extremism’ dichotomy. We argue that the latter fails to recognise that ‘philosophical’ unreasonableness often translates into political unreasonableness. Examining these non-liberal approaches not only indicates the apparent value of reason as reciprocity, it also supports a long-held charge against liberalism: that it is not able to uphold its promise of accommodating radical forms of diversity.