In a classical system, properties about the system can be represented as subsets of the phase space. They combine following the usual set-theoretic operations. Consequently the propositional structure associated to properties about a classical system follows the rule of classical logic. Motivated by Bohr's ideas that, the empirical content of a quantum physics is accesible only through classical physics, it is possible to interpret properties about the system in a different way. Concretely, we can encode the properties in an intuitionistic structure. In this work, we study a modal interpretation of quantum systems founded in this intuitionistic approach.