Measures without Measurement: A Critique of Ruffino’s Institutional Approach to the Contingent A Priori

This paper presents three objections to Marco Ruffino’s account of contingent a priori truths. First, I argue that Ruffino’s “Philonous’ Objection” neglects what is widely considered the mark of perception—namely, perceptual constancies, which allow stable representations despite variable sensory input. Second, I show that Ruffino’s institutional approach to the contingent a priori faces challenges under both relational (ratio-based) and monadic (property-ascribing) interpretations of measurement statements: the former diminishes the need for stipulation, while the latter risks conflating stipulative acts with empirical measurement outcomes. Third, I contend that Ruffino’s account risks an unwarranted commitment to social constructivism about brute physical facts.