Securing the objectivity of relative facts in the quantum world

Abstract

This paper compares and contrasts relational quantum mechanics (RQM) with a pragmatist view of quantum theory (DP). I first explain important points of agreement. Then I point to two problems faced by RQM and sketch DP?s solutions to analogous problems. Since both RQM and DP have taken the Born rule to require relative facts I next say what these might be. My main objection to RQM as originally conceived is that its ontology of relative facts is incompatible with scientific objectivity and undercuts the evidential base of quantum theory. In contrast DP?s relative facts have all the objectivity we need to accept quantum theory as scientific knowledge. But a very recent modification to RQM has successfully addressed my main objection, bringing the two views into even closer alignment.