How To Think More Clearly: Mental Models For Dummies

Two young fish are swimming along when they happen to meet an older fish swimming the other way. The older fish nods and says, “Good morning boys. How’s the water?” The two young fish smile, nod, and continue on their way. As they glide through the water in silence, eventually, one of them turns around to the other and says, “What the hell is water?”

The point of this parable — first told by David Foster Wallace — is that the most obvious and important realities are often the most difficult to see.

This is true for many aspects of our lives. Some of our experiences are so automated, so basic, that we’re not always aware of them.

For example, when I ask my clients about the nature of their inner voice, they often tilt their heads, think about the question, and then proceed to tell me that they don’t have an inner voice. Then I ask, “who just told you that?”

We all have an inner voice, of course, but sometimes it’s so pervasive that it’s difficult to see — like two little fish swimming around the ocean looking for water.

Making sense of reality

Mental models are psychological explanations of how things work. They provide us with a new way to see the world, and as a result, help us to make sense of reality.

Mental models also improve how we think, helping us to simplify complexity and better understand life.

For example, supply and demand is a mental model that helps us to understand the workings of our economy. Occam’s Razor is a mental model that helps us to seek the simplest solutions to our problems.

It’s important to note, however, that mental models are not reality. They are simply a map of reality, and only provide a representation of how something works. This makes them imperfect, because, by default, they are reductions of what they represent.

If this is the case, how are mental models useful?

Because the world is far too complex to keep all of the details in our brains, so we use mental models to simplify this complexity into bite-sized chunks that are easier to understand.

Stop swinging your hammer

The quality of our thinking is proportional to the models at our disposal.Why? Because the more models you have, the more likely you are to use the right ones to help you to see reality.

Cultivating a broad base of mental models is therefore critical if you want to make better decisions and think more effectively.

However, most people don’t have a broad base of mental models. Instead, they take the one or two models they do have and look for problems to stick them into.

This is best explained by the old adage, “To the man with a hammer, everything looks like a nail.”

As many people know, the majority of projects require more than a hammer. That’s why you need a variety of tools at your disposal. Only then will you be able to get the job done right.

The same is true for thinking. The quality of our decisions depends on the mental models in our heads. The problem is, most people are stumbling through life with little more than a hammer.

When you don’t use mental models, strategic thinking is like using addition when multiplication is available to you.” — Gabriel Weinberg

A multidisciplinary approach

Having a variety of mental models at our disposal is particularly important when facing complex problems, as it provides us with an ability to see the world through multiple lenses.

Unfortunately, however, society tends to look at reality through a single lens, dividing it into discrete topics to make it more accessible for study.

Shane Parrish captures this nicely in his latest book The Great Mental Models:

Most of us study something specific and don’t get exposure to the big ideas of other disciplines. We don’t develop the multidisciplinary mindset that we need to accurately see a problem. And because we don’t have the right models to understand the situation, we overuse the models we do have, and use them even when they don’t belong.

For example, an economist will often think in terms of supply and demand. A behavioural psychologist will think in terms of reward and punishment.

Through their respective disciplines, these individuals only see part of the situation, the part of the world that makes sense to them.

None of them, however, see the entire situation unless they are thinking in a multidisciplinary way. In short, they have blind spots, big blind spots.”

To better navigate the complexities of life, and to help us to see our blind spots, we need what Charlie Munger — one of the most successful people in the world — calls, a “latticework of mental models” (see image below).

Example of a latticework — interlacing strips of material forming a lattice

A latticework is a great way to conceptualise mental models because it demonstrates the interconnected nature of knowledge. Reality is not comprised of a unique set of disciplines. We only break it down that way to make it easier to digest.

However, once we learn something, we need to place it back into the interconnected system from which it came. Only then can we begin to build an understanding of the whole. This, as Shane notes, “is the value of putting the knowledge contained in mental models into a latticework.”

Mental Models: 4 of the best to get you started

For an in-depth review of mental models, see “The Best Way to Make Intelligent Decisions” by Farnam Street (Shane Parrish) and “Learn How to Think Better and Gain a Mental Edge” by James Clear.

To get you started, however, here are 4 of the best:

1. Inversion

Inversion is one of the most powerful mental models. Its origins can be found in the word “invert,” which simply means, turn upside down. As a thinking tool, it helps to identify and eliminate obstacles to success by tackling them from the opposite end of the natural starting point.

For example, say you were going on a date and you wanted to make a good impression. Instead of asking yourself, “What three things will make me look good?” ask yourself, “What five things will make me look like an idiot?

The idea is, rather than thinking about what you want, consider what you’d like to avoid. Or as Charlie Munger once said, “All I want to know is where I’m going to die, so I’ll never go there.”

Inversion won’t give you the answer to every problem, but it will always improve how you think about it.

2. First principles

First principles thinking is one of the best ways to reverse-engineer complex problems. Often called reasoning from first principles, it is the act of boiling things down to their most fundamental truths.

This is done by separating the underlying ideas from any assumptions they might be based on. A first principle, therefore, is a basic assumption that cannot be deduced any further.

An excellent example of first principles thinking comes via entrepreneur Elon Musk. In an interview with Kevin Rose, Musk expertly explained how Space Xused first principles to innovate at low prices.

In the early days of Space X, Musk was told that “battery packs are really expensive and that’s just the way they will always be.” Instead of settling for this answer, however, he broke the problem down into its fundamental parts.

First, he identified the material constituents of the batteries. Then he priced the materials on the London metal exchange and calculated the construction costs. As it turned out, the cost of building a battery from the bottom-up was only 13.3% of the original price.

By reasoning from first principles, Musk was able to cut through the fog of pre-existing beliefs to see opportunities others had missed.

3. Second-order thinking

Every action has a consequence, and each of these consequences has further consequences. These are called second-order effects.

Second-order thinking means thinking about these second-order effects. In other words, it means thinking about the effects of the effects.

This is a powerful thinking tool because things are not always as they appear. When we solve one problem, it’s often the case that we inadvertently create another one that’s even worse.

Second-order thinking, however, allows us to examine the long-term consequences of our decisions before we potentially make a bad call.

This process is best explained in terms of deficiencies. Here’s a great example from Shane Parrish’s latest book:

“We have been feeding antibiotics to livestock for decades to make the meat safer and cheaper. Only in recent years have we begun to realise that in doing so we have helped to create bacteria that we cannot defend against.”

In other words, instead of making meat safer, we have nurtured an army of dangerous, drug-resistant bacteria that have become part of our food chain.

Could these second-order effects have been avoided?

Yes. Anyone with a basic understanding of biology knows that organisms evolve and adapt, and those with shorter life cycles can do it more quickly. If second-order thinking was implemented, this situation could have been avoided.

4. Pareto Principle

Named after Italian polymath Vilfredo Pareto, who noticed that 80% of Italy’s land was owned by about 20% of its population, the Pareto Principle (also known as the 80/20 rule) states that, for many events, roughly 80% of the effects come from 20% of the causes.

For example:

  • 20% of your effort produces 80% of your gains.
  • 20% of your customers produce 80% of your profits.
  • 20% of your sources produce 80% of your happiness.

The point is to recognize that most things in life are not evenly distributed.

As such, to get better results, you should focus on the 20% that provides the greatest gains. In other words, focus on what works and do it better.

It should also be noted that mental models are not evenly distributed. There are thousands of mental models — some more useful than others — so you can implement the Pareto principle and use the 20% that work best for you.

Take away message

If you want to improve how you think, see the world more clearly, and ultimately, be more successful in life, look no further than mental models.

But let’s not kid ourselves. Mental models are not easily accessible. That’s why I wrote this article — in the hope of making them easier to understand.

I promise you this, however, once you start implementing mental models on a daily basis, the process will become more automated, internalized even. When that happens, it’s a complete game changer, and you can use mental models for everything.

Consider how you could implement the 4 models from this article on what you’ve just read:

  1. You could invert any potential gains from this post by asking yourself: “What might I lose by not implementing mental models into my life?”
  2. You could think about potential second-order effects if you were to implement mental models into your life. For example: “What practical impact might mental models have on my career, and how my this affect my home life?”
  3. You could reason from first principles about me, the author. Am I being honest? Do I have the required skills and knowledge to write this post? Is my reasoning sound?
  4. You could focus on the 20% that will give you the most gains. Maybe reasoning from first principles is particularly useful to you right now, and that’s your 20%.

My primary goal is to make mental models easier to understand, but also to make them more useful throughout our daily lives.

Why? Because they work. They work big time. And they will make a huge difference in your life if you use them on a daily basis.

My only ask is that you give it a shot.

Good luck on your mental model journey!

Liked this article? Check out for similar stories, and get the FREE program I developed to make remarkable changes in my recovery from 15 years of chronic heroin addiction.


  1. Mark

    Brian…. Really enjoyed the article and found it to be an eye-opener. However, something hit me in your closing, where you talk about starting to use mental models. I actually think that it’s impossible NOT to use mental models. I think that all our actions, thoughts, etc are based on some form of mental model. It’s just that some of them may be far from optimal, useful, etc….

    • Brian Pennie

      Hi Mark, thanks so much for the message but especially for your thoughts on starting to use the, You are so right. I will adjust that post.

  2. Vieer

    Nice Article! I’m definitely going to research it more with the intention to using mental models more.
    I’ve been positively inspired

  3. Lotanna

    Hello Brain
    I want to appreciate you for sharing this. This came at a right time as I am at a point in my life where I want to make big decisions on life and career. This really helped. I have always believed there should be systems and techniques one can adopt for better thinking. Please do point me in the direction of more books for it. Thanks again


Submit a Comment

Your email address will not be published. Required fields are marked *

You may like these

4 Ways To Help You Deal With Difficult People

4 Ways To Help You Deal With Difficult People

We are naturally drawn towards negativity. That’s why you’re standing here today. We evolved a bias towards negativity in order to survive. The cautious lived, the fearless died — it’s that simple. Consider your ancestors strolling through the jungle thousands of...

read more
A Simple Tool to Beat Smartphone Addiction

A Simple Tool to Beat Smartphone Addiction

Greg McKeown is a leadership expert, champion the lifestyle of essentialism, and New York Times Bestselling Author. I had the privilege of speaking to Greg last year. We discussed many topics including living in the moment, self-observation, and the hidden dangers of...

read more