System 2

In Daniel Kahneman's "Thinking, Fast and Slow", System 2 refers to reasoned, conscious thought process, for example weighing up options for a holiday or deciding what kind of ball to pitch in a game before actually throwing it. It is on contrast to System 1, which is the faster more unconscious reactions. System 2 is relatively slow, but open to explanation, communication and discussion. In AI, traditional symbolic AI corresponds most closely to human System 2 thinking.