Taking our point of departure in Kant’s book Zum ewigen Frieden, we note a seeming paradox which we believe has a wider application to legal states as such: while a legal state is supposed to impose strict duties, we only appear to have a loose duty to establish such a state. In order to investigate this seeming paradox, we will recapitulate what Kant says about strict and loose duties and examine in which terms he describes the perpetual peace. We will thus argue that perpetual peace is a loose duty. We will consider Kant’s reasons for this and endeavour to show through his parallel between individuals and states that the duty states have to enter a legal state is the same duty individuals have to enter this state. Finally, we will consider in what ways the above-mentioned paradox is only apparent and what this means for Kant’s philosophical position.