It has become somewhat a commonplace in recent political philosophy to remark that all plausible political theories must share at least one fundamental premise, ‘that all humans are one another's equals’. One single concept of ‘basic equality’, therefore, is cast as the common touchstone of all contemporary political thought. This paper argues that this claim is false. Virtually all do indeed say that all humans are ‘equals’ in some basic sense. However, this is not the same sense. There are not (...) one but two concepts of basic equality, and they reflect not a grand unity within political philosophy but a deep and striking division. I call these concepts ‘Equal Worth’ and ‘Equal Authority’. The former means that each individual’s good is of equal moral worth. The latter means that no individual is under the natural authority of anyone else. Whilst these two predicates are not in themselves logically inconsistent, I demonstrate that they are inconsistent foundation stones for political theory. A theory that starts from Equal Worth will find it near impossible to justify Equal Authority. And a theory that starts from Equal Authority will find any fact about the true worth of things, including ourselves, irrelevant to justifying legitimate action. This helps us identify the origin of many of our deepest and seemingly intractable disagreements within political philosophy, and directs our attention to the need for a clear debate about the truth and/or relationship between the two concepts. In short, my call to arms can be summed up in the demand that political philosophers never again be allowed to claim ‘that all human beings are equals’ full stop. They must be clear in what dimension they claim that we are equals—Worth or Authority. (shrink)