Inference is elementary and ubiquitous: Cognition always goes beyond the data. Thinking—including problem solving, decision making, judgment, planning, and argumentation—is here defined as the deliberate application and coordination of one’s inferences to serve one’s purposes. Reasoning, in turn, is epistemologically self-constrained thinking in which the application and coordination of inferences is guided by a metacognitive commitment to what are deemed to be justifiable inferential norms. The construction of rationality, in this view, involves increasing consciousness and control of logical and other inferences. This metacognitive conception of rationality begins with logic rather than ending with it, and allows for developmental progres...