Notes from reading the book series The Great Mental Models.

Contents

• Volume 1: General Thinking Concepts
  • The map is not the territory
  • Circle of competence
  • First principles thinking
  • Thought experiment
  • Second-order thinking
  • Probabilistic thinking
  • Inversion
  • Hanlon’s razor
  • Occam’s razor
• Volume 2: Physics, Chemistry and Biology
  • Physics
    • Relativity
    • Reciprocity
    • Thermodynamics
    • Inertia
    • Friction and Viscosity
    • Velocity
    • Leverage
  • Chemistry
    • Activation Energy
    • Catalysts
    • Alloying
  • Biology
• Volume 3: Systems and Mathematics

Volume 1: General Thinking Concepts

The map is not the territory

Maps (models, representations, examples, etc.) are reductions of reality. Maps are also affected by the biases of the creator.

Circle of competence

Within our circles of competence, we know exactly what we don’t know.

First principles thinking

Also known as reasoning from first principles. You separate the facts from the assumptions based on them. First principles thinking identifies the elements thar are non-reducible.

Socratic questioning can be used to establish first principles (this could be very useful when writing a paper…):

1. Clarify your thinking and explaining the origins of your ideas (why do I think this? What exactly do I think?).
2. Challenging assumptions. (How do I know this is true? What if I thought the opposite?).
3. Looking for evidence. (How can I back this up? What are the sources?).
4. Considering alternative perspectives. (What might others think? How do I know I am correct?).
5. Examining consequences and implications. (What if I am wrong? What are the consequences if I am?).
6. Questioning the original questions. (Why did I think that? Was I correct? What conclusions can I draw from the reasoning process?).

If your “whys” result in a statement of falsifiable fact, you have hit a first principle. If they end up with a “because I said so” or “it just is”, you know you have landed on an assumption that may be based on popular opinion, cultural myth, or dogma. These are not first principles.

So when we start with the idea that the way things are might not be the way they have to be, we put ourselves in the right frame of mind to identify first principles.

This is related to creativity. Develop your own ideas and thoughts.

Thought experiment

Second-order thinking

Probabilistic thinking

Inversion

Hanlon’s razor

Never attribute to malice that which is adequately explained by stupidity. (Wikipedia)

Hanlon’s Razor is meant to help us perceive stupidity or error, and their inadvertent consequences. It says that of all possible motives behind an action, the ones that require the least amount of energy to execute (such as ignorance or laziness) are more likely to occur than one that require active malice.

I liked this summary of the model. It’s not necessarily stupidity, but rather laziness, seeking the shortest path to completion, or lack of deep thought (e.g., when writing text replies such as emails or chat), that is often the reason why people do bad or stupid things. This model helps to understand this and can actually increase sympathy and understanding towards others.

Occam’s razor

Simple explanations are more likely to be true than complicated ones.

From Wikipedia: “…problem-solving principle that recommends searching for explanations constructed with the smallest possible set of elements”. “Also known as the principle of parsimony or the law of parsimony”.

Keep it simple. Important in work. Analyses, interpretations, presentations, etc.

Volume 2: Physics, Chemistry and Biology

Volume 3: Systems and Mathematics