In this paper, I discuss the possibility of reading the description of promise presented by Reinach in The Apriori Foundations of the Civil Law under the light of Husserl’s Ideas I. In order to present my argument, first, I briefly present the phenomenological method proposed by Husserl in Ideas I highlighting eidetic reduction. Second, I present the Reinachian description of social acts emphasizing the act of promising. Third, and finally, I try to demonstrate that the Reinachian description of the social (...) act of promising is the description of a universal and necessary relation, a synthetic and a priori statement and corresponds to the idea of promise. (shrink)