Isaiah Berlin’s doctrine of objective pluralism has been criticised as amounting in fact to ethical and political relativism. Berlin has relied on two arguments in attempting to refute this charge, those from common intelligibility and from shared values. I propose that the former argument alone is sufficient to refute relativism, whilst the latter argument leads not to pluralism but to a broad or narrow monism, depending on the number of shared values, since it fatally undermines the strong sense of incommensurability which is the defining characteristic of pluralism as a distinct and radical doctrine. Alongside his view that values are commonly intelligible, Berlin retains a minimal ethical universalism, framed in terms of his concept of ‘negative liberty’, or freedom from unwarranted interference. Some have argued that this inviolable ‘core’ of human freedom constitutes a form of liberal universalism. Whilst I concede that Berlin’s objective pluralism does exhibit a decidedly Western character, I argue that his ‘core’ is in fact a rational and pragmatic assertion of the minimal conditions for any meaningful and sustainable human life, whatever its diverse forms, rather than an endorsement of any universalist claims of liberalism, even minimal ones. I further argue that the common intelligibility of values on which Berlin’s refutation of relativism can be thought convincingly to rest is possible only because there is an essence and continuity in human ideas of a kind which is denied by Quentin Skinner and the Cambridge School, and which enable the historical understanding we clearly can achieve.