Reasoning from first principles is expensive: it burns time, annoys experts, and forces you to say “I don’t know” in rooms that reward confidence. Use it when stakes are high and analogies are lying—new physics, new markets, new cost structures—not when you’re choosing between two mature SaaS vendors.
This list moves from philosophical roots (what the idea is) to modern application (Musk, Feynman, Munger) so you can steal the technique without cosplaying genius.
Philosophical Roots
Aristotle on first principles (Metaphysics excerpts)
Aristotle · Primary Document
The original formulation—first causes from which everything else follows.
Feynman Lectures on Physics (selected)
Richard Feynman · Speech
Feynman's ability to derive from scratch rather than memorise—teaching as first-principles demonstration.
Modern Application
Elon Musk interviews on physics reasoning
Various · Interview
How Musk frames cost analysis and manufacturing decisions from material physics up.
Poor Charlie's Almanack
Charlie Munger · Book
Multidisciplinary reasoning as variant of first-principles across domains.
Thinking, Fast and Slow
Daniel Kahneman · Book · Amazon
Why analogy (System 1) dominates and when first-principles effort (System 2) is worth the cost.