The Great Mental Models vol.1 summary

Book: The Great Mental Models vol. 1 by Shane Parrish

Mental models are representations of how the world works, and this volume focuses on avoiding mistakes, identifying reliable knowledge, solving problems, and forecasting.

Main ideas:

Avoid mistakes

The map is not the territory: know the limits of your mental tools

• A map is a necessarily reduced representation of a complex territory.
• It’s useful to make some predictions.
• But you need to be aware of the limitations of your maps.

Circle of competence: stay in it

• Define the boundaries of your knowledge to avoid making decisions in areas you’re not enough knowledgeable.
• Your circle of competence is the field you studied most of your life, in which you have a long history of successful decisions taken pretty fast and with high confidence, and in which you know quite precisely what you don’t know and what can’t be known.
• Watch out for the shallow, basic knowledge that often gives the illusion of competence.

Acquiring wisdom: change your perspective, accept constructive critics, and get closer to the consequences

• First challenge: perspective. Our context, beliefs, and point of view limit us.
• Second challenge: ego. We fear being criticized.
• Third challenge: distance from consequences. We correct ourselves faster when we burn ourselves than when we see others burning themselves.

Identifying reliable knowledge

Falsifiability: the first step to real knowledge

• Falsifiability is a characteristic of a statement meaning that we can prove or disprove if it’s true.
  “I have a shirt in my suitcase” is a falsifiable statement, because we can open the suitcase, and check if it’s true or false.
• “God exists” is an unfalsifiable statement, because there is no way to tell if it’s true or not by direct observation.
• A theory must be falsifiable to be scientific. And then experimentation allows to confirm or deny if this theory was true.
• Unfalsifiable theories are not real knowledge. You can’t rely on unfalsifiable theories to make predictions. They are wishful thinking.

Correlation does not imply causation

• Correlated things may or may not be linked.
• Even if they are really linked, we don’t know which one is causing the other, and maybe they are actually connected to a third thing.
  • Student pot smoking is correlated with bad academic results. We might intuitively think that pot may have a negative effect on results. But having bad results can also actually be the cause for smoking pot. Or the two might reinforce each other. Or maybe a third element, like their general unhappiness in life, is the cause of both of these things. Low happiness can come from a variety of factors.
• The real links, causations, are sometimes harder to discover and they may be highly dependant on the individuals.
• Therefore, we must be prudent when we discover a correlation. Correlation is only the first step before a scientific experiment to determine the real links if there are any.

Solving problems

First-principles thinking: Going back to fundamentals

• Going back to fundamentals to find better ways to solve a challenge.
• Questions to ask yourself:
  • Why do I think that?
  • What exactly do I think?
  • How do I know this is true?
  • Can I list the opposing arguments?
  • What are the sources and pieces of evidence?
  • What might others think?
  • How do I know I am correct?
  • What if I am wrong?
  • What are the consequences if I am?
  • Why did I think that in the first place?
  • Was I correct?
  • What conclusion can I draw from the reasoning process?

Thought experiment

• Try to anticipate in your head the outcome of an experiment, with as much rigor as possible.
• It allows you to detect the limits of your circle of competences

Forecasting

Second-order thinking: anticipate the chain of consequences

• It helps focus on long-term benefits, and also to construct better arguments

Probabilistic thinking: evaluate the probability of all possible outcomes

• Instead of trying to forecast what will be the future, evaluate the probability of all possible futures.
• You need to identify what matters and check your assumptions.

Handling uncertainty

Inversion: avoid the things that lead to what you don’t want

• When there are too many possibilities and a lot of uncertainties, explore all the situations you don’t want.
• List how you might end up in them, and list what to avoid doing.
• Don’t try to be brilliant, try to avoid mistakes.

Occam’s Razor: Simple explanations are usually better

Hanlon’s Razor: incompetence, not malice

• Never attribute to malice that which is adequately explained by stupidity.
• Laziness, incompetence or bad incentives are more often the cause of problems than bad intentions.

Necessity and sufficiency

• Buying a lottery ticket is necessary but not sufficient to win.