[Apartheid law in South Africa] appears to be a clear and even extreme instance of that discrimination between different individuals which seems to me to be incompatible with the reign of liberty. The essence of what I said [in The Constitution of Liberty] was really the fact that the laws under which government can use coercion are equal for all responsible adult members of that society. Any kind of discrimination — be it on grounds of religion, political opinion, race, or whatever it is — seems to be incompatible with the idea of freedom under the law. Experience has shown that separate never is equal and cannot be equal.

"Conversation with Systematic Liberalism," Forum (September 1961).