Book Summary: The Great Mental Models I

This book is a terrific guide for the mental tools to help us better navigate the challenges and decisions we face in our everyday lives. They will help us think clearer, reason better, and hopefully make better decisions.

The Great Mental Models Volume 1

The following are the passages I most enjoyed from the book The Great Mental Models, Volume 1 by Shane Parrish and Farnam StreetAll content credit goes to the author(s).


1. The Map Is Not the Territory.

This mental model helps us “understand how to better use maps to navigate and relate to the world we live in“. The goal of a map is to reduce or abstract reality, in order to make it easier for others to understand it. They are a way of sharing knowledge with others. Some key concepts on how to use maps effectively.

Reality is the ultimate update.

  • Understand the reduction/abstraction that’s taking place. A map is a “model” of reality.
  • Remember that maps are static, but life is dynamic and constantly changing. Update the map when needed.

Consider the cartographer.

  • Maps are subjective representations of reality.
  • They are captured through the perspective of the cartographer.
  • Consider the context, values, intentions, and potential biases under which the map was built.

2. Circle of Competence

This mental model helps us “understand the reach and bounds of our own knowledge“. The goal of a circle of competence is to help you understand how to build deep knowledge on a subject, as well as how to navigate and operate safely outside of your circle of competence.

Individuals who are operating within a circle of competence display deep knowledge on the subject. This deep “expert” knowledge equips them with the flexibility to adapt and respond to changes and challenges in reality.

A simple example is the difference between a cook and a chef. A cook can follow a recipe effectively, but might struggle when faced with new ingredients and challenges. A chef might be able to adapt effectively to adversity, because of their deeper knowledge of ingredients and the conditions required to create desirable outcomes.

In order to build a circle of competence:

  • Be deeply curious about something. (a topic, problem, skill or subject area)
  • Act on your desire to learn, experience, and reflect on the subject.
  • Monitor your track record or keep a journal of your own performance.
  • Reflect on your own performance. Give yourself feedback.
  • Solicit feedback from external, outside or experts perspectives.

3. First Principles Thinking

This mental model helps us clarify complicated topics or “problems by separating the underlying ideas or facts from any assumptions based on them”.

In my opinion, it’s fundamentally an exercise in thought decomposition and self-questioning. Common techniques include Socratic Questioning and the Five Whys in order to dig deep at the truths underlying an idea or issue.

Here are the key questions you can use in your own thought process:

  • Clarify your point of view
    • What exactly do I think?
    • Why do I think this?
  • Challenge assumptions
    • How do I know this is true?
    • What if I thought the opposite?
  • Look for evidence
    • How can I back this up?
    • What are the sources?
  • Consider alternate perspectives
    • What might others think?
    • How do I know I am correct?
  • Examine consequences and implications
    • What if I am wrong?
    • What are the consequences if I am wrong?
  • Question the original questions
    • Why did I think that?
    • What conclusions can I draw from my reasoning process?

4. Thought Experiments

This mental model provides us with a tool we can use to imagine and explore a possibility or a premise. A thought experiment works in line with the scientific method, and just as rigorous as well. It is a reasoning process by which we imagine the impossible, re-imagine what we already know, and derive new ideas.

The steps you can follow to perform a thought experiment include:

  1. Ask yourself a question.
  2. Conduct and collect background research.
  3. Construct a hypothesis.
  4. Test the hypothesis with a ‘thought’ experiment.
  5. Analyze the outcomes of the experiment and draw conclusions.
  6. Reevaluate the hypothesis and ask yourself new questions to explore.

5. Second Order Thinking

This mental model helps us think more deeper and more holistically about a possible action or scenario. Simply put, second order thinking is “thinking of the effects of the effects”.

It helps us anticipate and think through the implications of short term actions. It’s also commonly used in systems thinking, when modelling the cause-and-effect relationships at work in a system.

Two areas of your life you can leverage this mental model include:

  • Prioritizing long-term interests over immediate gains
  • Constructing effective arguments.

Prioritizing Long Term Interests

For example, rather than having that extra drink or staying out that extra hour, consider the impact that will have on your sleep and therefore your energy the next day. Rather than spend some money today to buy something you want, what would happen if you saved that money and left it to grow in a retirement fund. This type of thinking isn’t hard, but it’s not necessarily enjoyable to defer short term pleasures for longer term goals.

Constructing Effective Arguments

If you are ever trying to persuade or express yourself on a topic, it helps to think through the second order implications of what you are proposing. Start from your premise. Then ask yourself, “and then what would be likely to happen?” or “what would need to be true?”. This will help you anticipate potential obstacles that need to be addressed or identify gaps in your arguments. By proactively bridging these gaps, you will be able to demonstrate that you’ve thoroughly thought through the matter and be more effective in conveying your point of view.


I greatly enjoyed this book. The author does an incredible job in sharing us the mental tools and exercises that we can apply to make better decisions in our everyday lives.

All content credit goes to the author(s). I’ve simply shared the bits I’ve enjoyed the most and found most useful.

Cheers ’till next time!

Alberto

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