Gilles Deleuze and Félix Guattari distinguish between the relativity of truth and the truth of the relative in their concept of partial observers. Unlike claims of a relativity of truth, for which truth is relative to different subject positions of human observers, the truth of the relative is inhuman, constituted by the experimental/experiential forces of the things themselves. Consider their conceptualization of perspectivism in light of quantum physics.
Heisenberg’s demon does not express the impossibility of measuring both the speed and the position of a particle on the grounds of a subjective interference of the measure with the measured, but it measures exactly an objective state of affairs that leaves the respective position of two of its particles outside of the field of its actualization, the number of independent variables being reduced and the values of the coordinates having the same probability. […] Perspectivism, or scientific relativism, is never relative to a subject: it constitutes not a relativity of truth but, on the contrary, a truth of the relative, that is to say, of variables whose cases it orders according to the values it extracts from them in its system of coordinates. […] In short, the role of a partial observer is to perceive and to experience, although these perceptions and affections are not those of a man, in the currently accepted sense, but belong to the things studied. […] Partial observers are forces. […] Partial observers are sensibilia. [What is Philosophy? (1994) pp. 129-131]