 Apparently, we are living in a quantum world since everything is constituted by atomic and subatomic particles. Hence classical physics seems merely to be a useful approximation to a world which is quantum mechanical on all scales. Such a view, which many modern physicists support, can be called quantum fundamentalism (Zinkernagel 2015, 2016). It can be defined as a position containing two components: (1) everything in the Universe is fundamentally of quantum nature (the ontological component); and (2) everything in the Universe is ultimately describable in quantum mechanical terms (the epistemological component). Thus, we may define quantum fundamentalism to be the position holding that everything in the world is essentially quantized and that the quantum theory gives us a literal description of this nature. The basic assumption behind quantum fundamentalism is that the structure of the formalism, in this case the wave function, corresponds to how the world is structured. For instance, according to the wave function description every quantum system may be in a superposition of different states because a combination of state vectors is also a state vector. Now, assuming that both the quantum object and the measuring apparatus are quantum systems that each can be described by a wave function, it follows that their entangled state would likewise be represented by a state vector. Then the challenge is, of course, how we can explain why the pointer of a measuring instrument enters a definite (and not a superposition) position, as experience tells us, whenever the apparatus interacts with the object. In a nutshell this is the measurement problem.