The roots of rationality

Functional accounts of mind, brain, and behavior have profoundly shaped thinking across many disciplines. Despite this common lens, the processes driving adaptive outcomes are often studied in isolation, leading to narrow and localized explanations. This paper brings together perspectives across fields by identifying six dynamics that enable agents to behave adaptively. These dynamics span multiple timescales and systems, including individual-level processes—thinking, learning, and development—and population-level processes—market selection, cultural evolution, and genetic evolution. We examine the reasons behind functional explanations of cognition and behavior, the conditions that foster rationality, and the interactions between adaptive processes. Our goal is to bring the cognitive, social, biological, and computer sciences into closer conversation by exposing researchers to a wide range of perspectives on adaptive decision-making.