This work takes as a starting point that Luis Recaséns Siches' "logic of the reasonable" theory is a predecessor of contemporary theories of legal argumentation such as Robert Alexy's one. Nevertheless, this work does not address this general thesis; its approach is more specific: to compare "balancing" and "equity" as the key concepts of what both authors Understand as "reasonableness". This paper aims to throw light on what meaning should be given to "reasonable" within legal argumentation. In this regard, this paper evidences that Recasens' Understanding of "reasonable" is comparable to Alexy's model only on the surface and that Recasens' model possesses two distinctive significant contributions which may be useful to show the way towards a lighter meaning of "reasonable" within legal argumentation.