In this paper we analyze the orthodox formulation of QM and argue that due to the choice of the concepts of ‘state’ and ‘system’ to present the postulates of QM, there has a been a metaphysical closure that has limited the development of the theory. We will argue that the basic postulates of QM imply the need to consider a metaphysics of entities that contradicts the formalism itself. In order to show this we will compare how the notion of entity is built in classical theories through the notion of invariance and in what sense a vector in Hilbert space does not follow these mathematical conditions. Finally, we claim that there is a main confusion responsible for regarding a vector in Hilbert space as an individual, namely, taking the formal equality in between multiple representations as a metaphysical identity.