Free Agent Skill
First Principles
Rebuild a problem from fundamental truths (physics, economics, unit costs, what's actually true regardless of convention) rather than by analogy to how things are normally done — the reasoning style associated with Elon Musk's approach to manufacturing cost problems and Richard Feynman's approach to physics problems.
Use when: the user is reasoning by analogy or precedent ("that's just how it's done," "industry standard is..."), is stuck because "everyone knows X isn't possible," or is pricing/costing something and the number seems anchored to convention rather than to actual inputs. Not a fit for problems that are genuinely about social convention or law, where precedent is the actual substance of the answer.
Install this skill
- Create a folder named `first-principles`.
- Save the skill content below as `SKILL.md` inside that folder.
- Place the folder in `~/.codex/skills/` for Codex, `.cursor/skills/` for Cursor or `.claude/skills/` for Claude Code.
- Describe the task normally. Your agent loads the skill when its description matches.
---
name: first-principles
description: Rebuild a problem from fundamental truths (physics, economics, unit costs, what's actually true regardless of convention) rather than by analogy to how things are normally done — the reasoning style associated with Elon Musk's approach to manufacturing cost problems and Richard Feynman's approach to physics problems. Use this whenever the user is reasoning by analogy or precedent ("that's just how it's done," "industry standard is..."), is stuck because "everyone knows X isn't possible," or is pricing/costing something and the number seems anchored to convention rather than to actual inputs. Not a fit for problems that are genuinely about social convention or law, where precedent is the actual substance of the answer.
---
# First Principles
Reasoning by analogy is usually fine and fast — most of the time, doing
what's normally done is a reasonable shortcut built on real accumulated
knowledge. First-principles reasoning is for the specific moments when
the analogy is the thing holding a wrong answer in place.
## The technique
1. **State the claim being taken for granted.** Usually something like
"X costs/takes/requires Y" where Y is treated as fixed. Say it plainly:
"the assumption here is that ___."
2. **Ask why that's true, one layer down.** Not "is it expensive" but
"what specifically makes it expensive — which inputs, at what
quantities, at what price?" Keep asking "why is *that* true" until you
hit something that's actually fundamental (raw material cost, a
physical constraint, a real regulatory requirement) rather than
another layer of "because that's how it's usually done."
3. **Rebuild the estimate from the fundamental layer up.** If you costed
out the raw inputs at their actual prices, what would this cost? This
number is often wildly different from the conventional number —
that gap is the interesting part, and it's exactly the gap Musk
pointed at with rocket manufacturing costs and battery costs.
4. **Explain the gap.** If the first-principles number is much lower than
the conventional one, the gap is usually markup, inefficiency,
regulatory capture, or a coordination problem — name which one, because
that's what tells you whether the gap is closeable.
5. **Check you haven't thrown away something real.** Precedent sometimes
encodes hard-won knowledge, not just inertia (this is why circle of
competence matters — see `mental-models`). Before concluding "this
should be way cheaper/faster/different," ask what the incumbent
approach might know that the rebuild is missing.
## Output
Show the layer-by-layer "why is that true" chain explicitly, not just the
final rebuilt number — the chain is what makes the conclusion trustworthy
rather than just a different unsupported guess.
More free skills
Prompt Refiner
Turns a vague request into an executable brief without silently inventing missing requirements.
Decision Framer
Separates the real choice from noise, then tests options against explicit criteria and uncertainty.
Meeting to Actions
Converts messy notes into decisions, owned actions, deadlines and unresolved questions.
Calibrated Forecasting
Turn a vague prediction or unstated confidence level into an explicit, calibrated probability estimate, following the practices Philip Tetlock found separated "superforecasters" from everyone else — breaking questions into sub-questions, checking base rates, updating in small increments as new information arrives, and tracking predictions against outcomes.
Decision Memo
Structure a real, consequential decision as a written narrative memo in the style Jeff Bezos used at Amazon — full sentences and paragraphs rather than bullet points, forcing the logic to be checked rather than gestured at, plus explicit classification of whether the decision is reversible (a "two-way door") or not (a "one-way door").
Feynman Teachback
Test and build genuine understanding of a concept using the Feynman technique — explain it as simply as possible, notice exactly where the simple explanation breaks down, and treat that break point as the thing to actually go learn.
Focus and Tradeoffs
Cut a bloated plan, roadmap, or list of priorities down to the one or two things that actually matter, in the tradition associated with Steve Jobs's product focus — "innovation is saying no to a thousand things."
Jobs to Be Done
Diagnose what "job" a customer is actually hiring a product, service, or workaround to do, using the Jobs-to-be-Done framework (Clayton Christensen's "progress in a specific circumstance," Bob Moesta's forces-of-progress and switch interview, Tony Ulwick's job statements and desired-outcome scoring).
Mental Models
Apply Charlie Munger's "latticework" approach — a small set of cross-disciplinary thinking tools (inversion, second-order effects, incentives, circle of competence, opportunity cost, base rates) to frame a vague or general problem.
Moat Analysis
Assess whether a competitive advantage is durable (a real "moat," in Warren Buffett and Charlie Munger's terms) or temporary, by checking it against the standard sources of durable advantage — switching costs, network effects, economies of scale, brand/trust, and regulatory or IP protection — rather than taking "we're ahead right now" at face value.
Negotiation Prep
Prepare for a high-stakes negotiation or hard conversation using tactical-empathy techniques associated with former FBI negotiator Chris Voss — labeling emotions, calibrated open-ended questions, mirroring, and getting to genuine "that's right" rather than a grudging "yes."
Postmortem / Retro
Extract a specific, reusable lesson after something succeeded or failed, following the principle (associated with Ray Dalio's "pain plus reflection equals progress") that outcomes only compound into better judgment if they're deliberately converted into a written, checkable lesson rather than just felt and moved past.
Premortem
Run a premortem — psychologist Gary Klein's technique of imagining a plan has already failed and working backward to explain why, which surfaces risks that forward planning misses because it counteracts the social and psychological pressure to seem confident.
Want this skill connected to a complete workflow?
Every skill is free and works independently. We can connect it to your tools, context, approval steps and other agents as a designed, tested pipeline for your business.