The dual-system theory, developed by psychologist Daniel Kahneman, proposes that there are two distinct systems of thought that operate in the human brain: system 1 and system 2.

System 1 thinking is fast, automatic, and unconscious, and is associated with emotions, intuitions, and gut feelings. It is responsible for many of the judgments and decisions that people make quickly and without much deliberation.

System 2 thinking is slower, more effortful, and more consciously controlled, and is associated with logic, analysis, and reasoning. It is responsible for many of the more complex and deliberate mental tasks that people engage in.

According to the dual-system theory, these two systems of thought operate in parallel and often influence each other, but they can also come into conflict. For example, a person might have an intuitive gut feeling about something that is contradicted by more logical and reasoned analysis.

The dual-system theory has had a significant impact on the field of psychology and has helped to shed light on the complex mental processes that underlie human decision-making.