First principles thinking: how to decide starting from fundamentals

When Elon Musk decided to build reusable rockets, everyone told him it was impossible. The cost of a rocket was around 65 million dollars — the market said so, suppliers confirmed it, and the aerospace industry had been repeating it for decades. But Musk didn't accept the market price as fact. He asked: what is a rocket made of? Aluminum, titanium, carbon fiber, copper. How much do these materials cost per kilogram? Two percent of the final price. Ninety-eight percent of the cost was industrial structure, not physics.

This is first principles thinking. Not asking "how much does a rocket cost?" but "why does it cost so much?". Not accepting the conventional answer, but breaking the problem down to its fundamental elements and rebuilding from there.

Deciding by analogy vs. deciding from first principles

Most of our decisions happen by analogy. We look at what others have done in similar situations and do the same. "My colleagues are buying houses, so I should buy a house." "Other startups in the sector do this kind of marketing, so I'll do the same." "My parents made this choice, so it's the right choice."

Analogy is efficient. It saves time and reduces uncertainty. But it has a fatal flaw: it only works if conditions are identical. And conditions are never identical. Your financial situation isn't your colleague's. Your product isn't the other startup's. Your parents' world isn't your world.

First principles thinking asks: "What is actually true in this situation?" Not what others think, not what past experience suggests, but what are the fundamental facts to start from.

First principles and DAMM: a powerful combination

The DAMM framework becomes even more effective when combined with first principles thinking. The idea is simple: decompose the decision into its fundamental elements, then apply DAMM to each element separately.

Take the example of buying a house. The surface-level question is: "Should I buy a house or not?" Analogical thinking answers by looking at what others do. First principles thinking breaks the decision into fundamental elements.

Element 1: Location. Where do you want to live for the next 5-10 years? Not where your friends live or where it's "logical" to go, but where your lifestyle works best. Delimitation here asks: which areas would put daily quality of life at risk (extreme commuting, isolation, unsustainable costs)?

Element 2: Financial capacity. Not "how much mortgage can I get from the bank" (analogy), but "what monthly payment can I sustain even if I lose my job for six months?" Margin answers this question directly.

Element 3: Life plans. Not "people my age buy houses" (analogy), but "is my professional and personal trajectory compatible with a twenty-year property commitment?" Asymmetry reveals that if the answer is uncertain, the potential cost of being locked in exceeds the benefit of ownership.

Element 4: Market timing. Not "prices always go up" (analogy), but "what is the price-to-rent ratio in this specific area?" The Minimum Move might be renting for a year in the target area before buying.

The entrepreneur example

Second example: starting a business. Analogical thinking says: "90% of startups fail, so it's too risky." But this statistic hides everything. Which startups fail? Why? In which sector? With what cost structure?

First principles thinking decomposes the decision differently. What problem do you want to solve? Does someone have this problem enough to pay for a solution? Can you build a minimal version of the solution with the resources you have? Each question reveals hidden assumptions that analogical reasoning covers under generic statistics.

Applying DAMM to these elements: Delimitation identifies the real boundary — perhaps it's not "don't start the business" but "don't invest more than X euros and Y months before having your first paying customer." Asymmetry measures what you gain if it works vs. what you lose if it doesn't, on each element separately. The Minimum Move becomes: validate the idea with 10 potential customers before leaving your job.

The practical method

To apply first principles thinking to your decisions, follow these steps:

1. **Identify hidden assumptions.** Write down the decision and then ask yourself: "What am I assuming to be true without having verified it?" Each assumption is a point to examine.

1. **Break it down into fundamental elements.** Don't treat the decision as a single block. Separate it into its components: financial, emotional, temporal, relational, professional.

1. **Verify each element independently.** For each component, look for real data, not opinions. Not "they say the housing market goes up," but "what has the price trend been in this area over the last 10 years?"

1. **Apply DAMM to each element.** Each component has its own Delimitation, its own Asymmetry, its own Margin, its own Minimum Move. The overall picture that emerges is far more nuanced than a simple "yes or no."

Why this approach works

First principles thinking combined with DAMM works because it attacks two cognitive weaknesses simultaneously. First principles eliminate decisional conformism — the tendency to copy others without analyzing your own situation. DAMM eliminates paralyzing fear — the tendency not to decide because risk seems enormous when the decision is one indivisible block.

By decomposing and protecting each element, the impossible decision becomes a series of manageable steps. You're no longer deciding "the future of your life." You're deciding the next step for each component. And that is exactly how the best decisions get made.