Isaiah Berlin’s humanistic liberalism is still an influential theory and an implacable antidote against extremism and fanaticism in all their guises. The author of this article notes that one of the main contributions of this theoretician born 100 years ago consists in gaining awareness that there is a multiplicity of values in plural societies which cannot be reduced to a single principle, or a universal permanent combination of values applicable to all individuals and all practical cases. However, Berlin’s defence of value pluralism is in no way a gratuitous concession to relativism or scepticism. Without a doubt, there is a role reserved for reason in moral conflicts. However, “reasonable” discrimination between values is much more context-dependent, even on an individual scale, than what moral, political or religious “rationalist” conceptions assume.