Two modes of thinking

Tags: psychology thinking

In Thinking, Fast and Slow [1], Daniel Kahneman states that there are two "modes" of #thinking:

  1. System 1: the instant, unconscious, automatic system
  2. System 2: the deliberate, thoughtful, rational system

System 1 dictates the vast majority of our decision making and behavior because System 2 thinking requires a lot of energy and is tiring; therefore, our brain only engages in System 2 thinking when called upon to do so.

System 1 is also heavily subject to significant cognitive biases and operates on heuristics and patterns more than it does logic or reason.

The consequence of this is that much of people's behavior is biased and can often appear irrational or illogical.


  1. Kahneman, Daniel. Thinking, Fast and Slow. 1st ed. New York: Farrar, Straus and Giroux, 2011.