Decision-making is argued to be intrinsically embedded in the historical emergence of probability and statistics, as well as in the justification for their inclusion as school mathematics subjects. In this article I investigate the role of decision in probability and statistics in both the current and upcoming Chilean upper secondary school mathematics curricula. Drawing upon Fairclough’s model for Critical Discourse Analysis, I analyse selected texts as examples of broader discourse practices, in particular, I focus in assumptions, modalities, and intertextualities. They evidence the role of decision-making as legitimation of the subject matter and as a mediator of agency by teachers and students. I claim there is a shift towards less appeal to authority in legitimising the curriculum, and an increasing responsibility of students in the educational process.