In this paper we attempt to physically interpret the Modal Kochen–Specker (MKS) theorem. In order to do so, we analyze the features of the possible properties of quantum systems arising from the elements in an orthomodular lattice and distinguish the use of “possibility” in the classical and quantum formalisms. Taking into account the modal and many worlds non-collapse interpretation of the projection postulate, we discuss how the MKS theorem rules the constraints to actualization, and thus, the relation between actual and possible realms.Fil: de Ronde, Christian. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Filosofía ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Vrije Unviv...