 The locality of physical interactions defines the preferred basis. As described in Section 3.5, only localized states of macroscopic objects are stable. And indeed, due to the extensive research on decoherence, the problem of preferred basis is not considered as a serious objection anymore, see Wallace 2010a. Singling out position as a preferred variable for solving the preferred basis problem might be considered as a weakness, but on the other hand, it is implausible that out of a mathematical theory of vectors in Hilbert space one can derive what our world should be. We have to add some ingredients to our theory and adding locality, the property of all known physical interactions, seems to be very natural (in fact, it plays a crucial role in all interpretations). Hemmo and Shenker 2020 also argued that something has to be added to the Hilbert space structure, but viewed the addition of a locality of interaction postulate as the reason that Ockham’s razor does not cut in favour of the MWI. Note, that taking position as a preferred variable is not an ontological claim here, in contrast to the options discussed in the next section.