ABSTRACT
Over the years, Cartwright’s views of quantum theory have changed twice. At first, she defended a version of quantum fundamentalism which was associated with a strong realistic interpretation of the wave functions of quantum mechanics. In 1975, she believed that quantum states and their superpositions belong to the ontological commitments of quantum theory, whereas mixtures do not (Cartwright 1975; 1983: 165, 169). The superpositions she took for real referred to states after measurements. Her argument was based on the theory of Daneri, Loinger, and Prosperi, according to which after a measurement a superposition dresses up as a mixture, in the sense that it makes the same statistical predictions (Daneri et al. 1962). According to this theory, measurement is an amplification process which ends up in thermodynamic equilibrium states with ergodic properties. The theory predicts quantum states that look classical even though they still are superpositions.2
