Unwanted Arbitrariness

I propose a new fundamental principle in ethics: everyone who makes a choice has to avoid unwanted arbitrariness as much as possible. Unwanted arbitrariness is defi ned as making a choice without following a rule, whereby the consequences of that choice cannot be consistently wanted by at least one person. Other formulations of this anti-arbitrariness principle are given and compared with very similar contractualist principles formulated by Kant, Rawls, Scanlon and Parfit. The structure of arbitrariness allows us to fi nd ways to avoid unwanted arbitrariness. The two most important implications of the anti-arbitrariness principle are discussed: non-dictatorship and non-discrimination.