Read my point about the status of the concept
of 'causality'. You are basically stuck with a circular argument in which that concept, plus 'existence' per se
is taken as 'given'. In the history of Philosophy, such a mechanistic view was countered by the 'idealism' movement in which, following Kant, no access to noumena
(things-in-themselves....independent realities) was the starting point. All 'things' were considered to be 'phenomena' or 'mental experiences' embedded in social communicative networks. Such networks (paradigms) 'shift' as what we call 'knowledge' progresses(Kuhn), and it is within the realm of such shifting that the political angle has its place.
I don't intend to re-iterate the point further. Reference to the copious literature on 'the sociology of knowledge' should alone be sufficient to underscore the point irrespective of philosophical objections to the simplistic 'realism' of 'physics' that you are clinging to.