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An Introduction to First Principles Thinking


An Introduction to First Principles Thinking

Teddy Daiell shares an article designed to develop the practice of questioning every assumption you think you know about a given problem with first principles thinking. 

Short Description: Reduce a complex situation down to its core, objective facts, removing any subjective preconceptions and assumptions, and then employ reason and logic to reach novel conclusions.

Long(er) Description: “[Separate] the underlying ideas or facts from any assumptions based on them. What remains are the essentials. If you know the first principles of something, you can build the rest of your knowledge around them to produce something new.” (Farnam Street)

Related Examples:

Vehicle Design – Starting from last year’s model vs. the first principles of physics and chemistry.

Economic Forecasting – Relying on others’ forecasts vs. deriving your own conclusions from key drivers.

Creating a Workout / Fitness Program – Using a one-size-fits-all training program vs. learning the fundamentals of physical fitness and matching those to your personal goals and constraints.

Reframe Dominant Beliefs – “In a nutshell, the process begins with identifying an industry’s foremost belief about value creation and then articulating the notions that support this belief. By turning one of these underlying notions on its head—reframing it—incumbents can look for new forms and mechanisms to create value. When this approach works, it’s like toppling a stool by pulling one of the legs.”

Related Quotes:

“When you simply ignore the box and build your reasoning from scratch, whether you’re brilliant or not, you end up with a unique conclusion—one that may or may not fall within the box.” ~ Tim Urban

“Top-rung thinkers form hypotheses from the bottom up, by reasoning from first principles. When you reason from first principles, you do your best to ignore conventional wisdom and your own preconceptions, and you focus only on fundamental facts. You treat those core facts—the “first principles”—like puzzle pieces, and using only those pieces, you employ rationality to puzzle together a conclusion.” ~ Tim Urban

“I stress-tested my opinions by having the smartest people I could find challenge them so I could find out where I was wrong. I never cared much about others’ conclusions—only for the reasoning that led to these conclusions. Through this process, I improved my chances of being right, and I learned a lot from a lot of great people.” ~ Ray Dalio


Key points include:

  • Dimensionality Reduction
  • Orthogonality 
  • Interests vs. Positions


Read the full article, Mental Model Fundamentals: First Principles Thinking, on LinkedIn.