Recent no-go theorems challenging the absoluteness of events have highlighted the possibility that dynamical facts in quantum theory are observer-relative. This thesis examines the metaphysical and conceptual foundations of quantum relativism, focusing on Relational Quantum Mechanics (RQM). It analyzes arguments for relativism through Wigner’s Friend and Extended Wigner’s Friend thought experiments, explores the link between relative physical facts and experiences, and offers the first metaphysical definition of "relative facts."

The thesis argues:

RQM supports a perspectival retro-determination of past events based on later acquisition of information;

Quantum relativists must also relativize facts about observers’ experiences;

the strongest arguments for relativism lead to unbounded higher-order relativity, precluding any absolute 'view from nowhere';

Only a metaphysical framework that relativized the composition of reality itself can accommodate such an unrestricted iteration.

These conclusions deepen our grasp of a thoroughly perspectival quantum world.