This chapter argues that intelligence-related individual differences in thinking are largely the result of differences at the algorithmic level of cognitive control. Intelligence tests thus largely fail to tap processes at the reflective level of cognitive control. As understanding rational behavior necessitates understanding processes operating at both levels, an exclusive focus on intelligence-related individual differences will tend to obscure important differences in human thinking. The chapter explicates the difference between the algorithmic and reflective level of processing as they are understood in contemporary dual-process theories of cognition. Knowledge bases, both innate and derived from experience, also importantly bear on rationality. The term mindware is used to refer to these knowledge bases. The tripartite model of mind presented in the chapter explains why rationality is a more encompassing construct than intelligence. Rationality requires the proper functioning of both the reflective and the algorithmic mind.