Scientific literacy concerns understanding the methodology of science at least as much as understanding scientific knowledge. More than this, it also requires an understanding of why the methodology of science delivers (or fails to deliver) epistemic credibility. To justify scientific claims as credible, it is important to understand how the nature of our reasoning is embodied in scientific methodology and how the limits of our reasoning are therefore the limits of our inquiry. This paper makes explicit how aspects of critical thinking, including argumentation and reasoning, underpin the methodology of science in the hope of making the development of scientific literacy in students more actionable.