Kuhn left many readers with the impression that his version of paradigm choice was not a process governed by reason. That impression was correct. This chapter examines the development of Kuhn’s thinking on paradigm choice during and after Structure, focusing on a philosophical challenge here called the “puzzle of promise”: how can paradigm choice be conceived of as rational if it is, as Kuhn claims, made in defiance of the evidence from problem solving? The chapter argues that later developments of Kuhn’s views elaborate a platform for solving this puzzle, but that he himself always clung to the view that paradigm choice is an arational process.

This chapter surveys several entry points through which science becomes legally relevant in WTO law and in trade disputes. It reviews the elaborate techniques of WTO panels and the Appellate Body to engage with scientific evidence in cases involving environmental and health risks. The chapter addresses the WTO’s expert consultation system and discusses the changing canons of deference afforded to WTO members in adopting science-based SPS measures. It extensively analyses the epistemic nature and significance of the two-stage standard of review, under which WTO dispute settlement bodies scrutinize the coherence of the reasoning provided by the risk assessor. The chapter concludes with identifying argumentative techniques in the WTO jurisprudence justifying adjudicatory conclusions concerning scientific evidence and arguments. It distinguishes reasoning methods built on scientific, intuitive, and legal rationality. The chapter also identifies an additional particular reasoning style, which utilizes concepts that are labelled as 'hybrid' benchmarks.

This chapter argues that downplaying science in the judicial inquiry has a fundamental impact on the ways in which legitimate and persuasive reasoning can be crafted. More particularly, not respecting the cognitive authority of science undermines the epistemic legitimacy of decisions. The central yardstick in this respect is not that using more science would necessarily result in better-reasoned judgments; rather, the legitimacy of judgments hinges on how adjudicators reflect on the scientific aspects of disputes in the reasoning. The chapter identifies four types of epistemic yardsticks with which international fora justify the acceptance or rejection of a particular science-based claim. The chapter differentiates between legal, scientific, hybrid, and intuitive reasoning styles, and discusses the benefits and trade-offs of each of them in terms of factual accuracy, epistemic non-arbitrariness, practical feasibility, and preserving the judicial monopoly over adjudication. The chapter also offers solutions for remedying applicable shortcomings, and offers recommendations for selecting a sound approach to scientific knowledge in the judicial reasoning under particular circumstances.