Abstract
Metaphysical underdetermination arises when we are not able to decide, through
purely theoretical criteria, between competing interpretations of scientific theories with different metaphysical commitments. This is the case in which non-relativistic quantum mechanics (QM) finds itself in. Among several available interpretations, there is the one that
states that the interaction with the conscious mind of a human observer causes a change in
the dynamics of quantum objects undergoing from indefinite to definite states. In this paper,
we argue that there seems to be also a metaphysical underdetermination concerning London
and Bauer’s theory of measurement between two methods of phenomenological reduction:
the eidetic and the transcendental approaches. Recently, Steven French argued that both
methods can be combined in order to interpret London and Bauer’s formalism. However, in
this paper we argue that the eidetic one is the only viable phenomenological way to interpret
this particular theory of measurement in QM based on the formalism presented by London
and Bauer, hence breaking this phenomenological underdetermination.