Aristotle laid the foundations of the philosophy of science in his Posterior Analytics. The early Stoics also did serious work in the field, but then it languished for almost a millennium and a half until the mid-thirteenth century, when Parisian scholastics took up the subject again. This chapter presents one of the most original thinkers of the second half of the thirteenth century. He was active at the University of Paris in the 1260s and 1270s, where he was known as Boethius de Dacia or Boethius Dacus. The core of Boethius' solution is a substitution of causal relationships for ordinary things as an answer to the question what scientific knowledge is knowledge of and what scientific propositions are about. The way Boethius conceived of science, the rule-governed disputations held in the arts faculty were the perfect preparation for doing serious science. The disputants were trained in maintaining consistency and in sticking to the rules of each particular type of disputation.