Political action is unpredictable because it unfolds among a plurality of independent actors. This unpredictability generates a fundamental puzzle: If an actor cannot know where her initiative will lead, what motivates and guides her in her doings? The aim of this paper is to develop and defend the solution to the puzzle that we can find in the thought of Hannah Arendt, namely the idea that political action is – or should be – motivated and guided by principles, principles like (...) justice, equality, or honour. Such principles must be distinguished from goals because they do not designate a specific state of affairs, but are general ideas that allow for diverse implementations. I show that this distinction is of great practical importance for the actors involved, since their outlook and their attitude towards others will differ depending on whether they see their activity as aimed at a goal or as guided by a principle. (shrink)