Notes on Mental Models and First Principles

02 Sep 2021

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Key concepts

A first principle is a proposition or an assumption on which true knowledge is based. In science, theories, methods, and laws are derived from first principles. Axioms and postulates are the first principles in mathematics.

“In every systematic inquiry (methods) where there are first principles, or causes, or elements, knowledge and science result from acquiring knowledge of these; for we think we know something just in case we acquire knowledge of the primary causes, the primary first principles, all the way to the elements.” – Aristotle

The opposite is reasoning by analogy: building knowledge and solving problems based on prior assumptions, beliefs and widely held best practices approved by majority of people.

First principles thinking asks: is it true?

Reasoning by analogy says it was done before, therefore, it is true.

There are many comparisons between analogous and first principles thinking. The coach and the play stealer, the chef and the cook, or the architect and the draftsman. You can see the hint. The former build something unique and the latter follow instructions.

A cognitive map is any visual representation of a person’s (or a group’s) mental model for a given process or concept.

A mind map is cognitive map consisting of a tree that represents a central topic and its subtopics.

A concept map is another type of cognitive map in which nodes represent concepts and are related through labeled, directed edges that illustrate relationships between them.

Methodologies

Best source

1. Five Whys

Wikipidia

An example of a problem is: The vehicle will not start.

  1. Why? – The battery is dead. (First why)
  2. Why? – The alternator is not functioning. (Second why)
  3. Why? – The alternator belt has broken. (Third why)
  4. Why? – The alternator belt was well beyond its useful service life and not replaced. (Fourth why)
  5. Why? – The vehicle was not maintained according to the recommended service schedule. (Fifth why, a root cause)

2. Questions method #1

  1. Clarifying 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?)

3. Questions Method #2

Method source

  1. Identify your goal
  2. List the obstacles
  3. Question these obstacles
  4. Find your first principles by answering the questions

4. Generic parts technique

There are two basic questions that you ask as part of this process:

  1. Can it be broken down further?
  2. Does my description of the object imply a use?

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