A Simple Introduction to Mental Models

This article is an excerpt from my book The Decision-Making Blueprint.

“Why did the chicken cross the road?”

According to biologist Robert Sapolsky, the answer to that question will depend on the expert you ask1. For example:

  • A biologist might say: “The chicken crossed the road because it saw a potential mate on the other side.”
  • A kinesiologist might say: “The chicken crossed the road because the muscles in its legs contracted and pulled its leg bones forward.”
  • A neuroscientist might say: “The chicken crossed the road because the neurons in its brain fired and triggered it to move.”

Interestingly, all of these experts are correct. But at the same time, none of them are seeing the entire picture. And that’s because all of them are looking at the question through the lens of their unique expertise.

Mental Models

A mental model is a representation of how something works. It’s a concept, framework, or worldview stored in your mind that you use to interpret, simplify, and understand the world. For example:

  • Second-Level Thinking is a mental model that helps you identify subsequent consequences before they happen.
  • Incentives is a mental model that helps you understand what motivates people.
  • Entropy is a mental model that helps you understand how everything in life moves from order to disorder.

Mental models guide your perceptions, thoughts, and actions. They are the thinking tools your mind uses to explain reality, solve problems, and make decisions.

The Limitations of Expertise

The quality of your decisions depends on the mental models in your mind. If you have a lot of mental models—a big toolbox—you’re better equipped to perceive reality accurately and find solutions to problems.

Most of us, however, don’t have a big toolbox to pick and choose from. Instead, we default back to just a few tools again and again. Usually, these are mental models related to our discipline and expertise.

A biologist will tend to think in terms of evolution. A kinesiologist will tend to think in terms of mechanisms of movement. And a neuroscientist will tend to think in terms of the nervous system and the brain.

The more you master a particular mental model, the more you’ll start applying it everywhere. You’ll cram reality into your model of it. And so what looks like expertise can actually become a limitation.

As the proverb goes: “If all you have is a hammer, everything looks like a nail.”

Expanding Your Toolbox

If your set of mental models is limited, so is your ability to find solutions. To make wise choices, you have to collect a wide range of mental models. In other words, you have to have a well-equipped decision-making toolbox.

The good news? Acquiring new thinking tools is straightforward. Once you learn a mental model, you can’t unlearn it. And from that point forward, you can use it anytime you want to shift your perspective and find new solutions.

What’s more, you don’t have to master every idea from every discipline to become a great thinker. If you can just get a firm grasp of a few fundamental models, you’ll develop a remarkably accurate and useful picture of reality.

In the articles below, I cover the most widely applicable mental models. I hope you’ll find them useful!


  1. Behave: The Biology of Humans at Our Best and Worst by Robert M. Sapolsky

Mental Models Articles