The defence of ethical universalism can be grounded in assertion that discussion, if it is to be meaningful, assumes the validity of some minimal agreement in principles. If, however, it is a fundamental fact that the participators in the discussion of ethical questions are (at least potentially) all people, then the principles of that discussion will have universal validity. Hume’s Law, which in this study is examined in detail and precisely formulated, does not allow us to seek a generally valid basis for ethical discussion exclusively in the domain of factual assumptions. This means that the universal validity of some basic evaluative ethical principles must be recognised.