Skip to main content
Heuristics

System 1 and System 2 (Dual Process Theory)

Dual-process accounts distinguish fast, automatic, intuitive System 1 from slow, deliberate, analytical System 2. Taleb argues that reasoning errors often arise when we believe we are using System 2 while relying on System 1.

THE IDEA

The Shortcuts

Thinking and reasoning have shortcuts that can contribute to our crippling shallowness. These defects in reasoning have been cataloged and investigated by a powerful research tradition represented by a school called the Society of Judgment and Decision Making (the only academic and professional society of which I am a member, and proudly so; its gatherings are the only ones where I do not have tension in my shoulders or anger fits). It is associated with the school of research started by Daniel Kahneman, Amos Tversky, and their friends, such as Robyn Dawes and Paul Slovic. It is mostly composed of empirical psychologists and cognitive scientists whose methodology hews strictly to running very precise, controlled experiments (physics-style) on humans and making catalogs of how people react, with minimal theorizing. They look for regularities. Note that empirical psychologists use the bell curve to gauge errors in their testing methods, but as we will see more technically in Chapter 15, this is one of the rare adequate applications of the bell curve in social science, owing to the nature of the experiments. Examples include judgments about a flood in California and the confirmation bias discussed in Chapter 5. These researchers have mapped our activities into (roughly) a dual mode of thinking, which they separate as “System 1” and “System 2,” or the experiential and the cogitative. The distinction is straightforward.

System 1, the experiential one, is effortless, automatic, fast, opaque (we do not know that we are using it), parallel-processed, and can lend itself to errors. It is what we call “intuition,” and performs these quick acts of prowess that became popular under the name blink, after the title of Malcolm Gladwell’s bestselling book. System 1 is highly emotional, precisely because it is quick. It produces shortcuts, called “heuristics,” that allow us to function rapidly and effectively. Dan Goldstein calls these heuristics “fast and frugal.” Others prefer to call them “quick and dirty.” Now, these shortcuts are certainly virtuous, since they are rapid, but, at times, they can lead us into some severe mistakes. This main idea generated an entire school of research called the heuristics and biases approach (heuristics corresponds to the study of shortcuts, biases stand for mistakes).

System 2, the cogitative one, is what we normally call thinking. It is what you use in a classroom, as it is effortful (even for Frenchmen), reasoned, slow, logical, serial, progressive, and self-aware (you can follow the steps in your reasoning). It makes fewer mistakes than the experiential system, and, since you know how you derived your result, you can retrace your steps and correct them in an adaptive manner.

Most of our mistakes in reasoning come from using System 1 when we are in fact thinking that we are using System 2. How? Since we react without thinking and introspection, the main property of System 1 is our lack of awareness of using it!

Recall the round-trip error, our tendency to confuse “no evidence of Black Swans” with “evidence of no Black Swans;” it shows System 1 at work. You have to make an effort (System 2) to override your first reaction. Clearly Mother Nature makes you use the fast System 1 to get out of trouble, so that you do not sit down and cogitate whether there is truly a tiger attacking you or if it is an optical illusion. You run immediately, before you become “conscious” of the presence of the tiger.

Emotions are assumed to be the weapon System 1 uses to direct us and force us to act quickly. It mediates risk avoidance far more effectively than our cognitive system. Indeed, neurobiologists who have studied the emotional system show how it often reacts to the presence of danger long before we are consciously aware of it—we experience fear and start reacting a few milliseconds before we realize that we are facing a snake.

Much of the trouble with human nature resides in our inability to use much of System 2, or to use it in a prolonged way without having to take a long beach vacation. In addition, we often just forget to use it.

When to use it

  • In financial trading, compare a gut judgment (System 1) with an explicit analysis (System 2), checking the evidence, assumptions, and limits of any model used.

  • During emergency response, fast System 1 reactions are crucial for immediate safety, but after the crisis, System 2 debriefing helps identify and correct errors.

  • In product design, understanding that users often rely on System 1 can help create intuitive interfaces, while System 2 supports complex tasks.

FROM THEORY TO EVERYDAY LIFE

In practice

01

The Tiger Scenario

When encountering a shape that might be a tiger, System 1 triggers immediate fear and running without conscious analysis. This quick reaction is beneficial for survival but can lead to false alarms if the shape is actually a harmless shadow.

02

Round-Trip Error

Confusing 'no evidence of Black Swans' with 'evidence of no Black Swans' is a classic System 1 error. The automatic assumption that absence of proof is proof of absence requires effortful System 2 reasoning to override.

✳

A MOMENT TO REFLECT

Put it to work.

  1. Think of a recent decision where you relied on gut feeling. Was it correct? Could a slower, more analytical approach have improved the outcome?

  2. In what situations is it beneficial to override your System 1 intuition with System 2 reasoning?

  3. How might you design your environment to encourage more System 2 thinking in areas where mistakes are costly?

Connected ideas

Another lens can bring the same problem into focus.

References

  1. Thinking, Fast and Slow — Daniel Kahneman (2011)
  2. Blink — Malcolm Gladwell (2005)

CONTINUE THE CONVERSATION

Source texts

  • The Black Swan The Impact of the Highly Improbable With a new section On Robustness and Fragility (Nassim Nicholas Taleb)
← More heuristics