Free Agent Skill
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.
Use when: the user brings a fuzzy problem that hasn't been broken down yet, asks "how should I think about this," seems to be reasoning from a single framework when the problem is really cross-disciplinary, or seems stuck circling the same angle repeatedly. This is the default general-purpose skill when no more specific skill (decision-memo, premortem, first-principles) obviously fits better.
Install this skill
- Create a folder named `mental-models`.
- 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: mental-models
description: 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. Use this whenever the user brings a fuzzy problem that hasn't been broken down yet, asks "how should I think about this," seems to be reasoning from a single framework when the problem is really cross-disciplinary, or seems stuck circling the same angle repeatedly. This is the default general-purpose skill when no more specific skill (decision-memo, premortem, first-principles) obviously fits better.
---
# Mental Models
Most bad reasoning isn't a lack of intelligence — it's using one lens on a
problem that needs several. This skill applies a short list of
cross-disciplinary tools to reframe a fuzzy problem before diving into
solving it. Don't run through the whole list mechanically — pick the 1-3
tools that actually bite for this problem.
## The tools
**Inversion.** Instead of asking "how do I succeed," ask "what would
guarantee failure, and am I doing any of that?" Working backward from
failure surfaces risks that forward reasoning misses.
**Second-order effects.** The first-order effect of an action is usually
obvious and is why people do it. The second- and third-order effects are
where most surprises live. Ask: "and then what happens? And then what
happens after that?" at least twice.
**Incentives.** Look at what people are actually rewarded for, not what
they say their goals are. Munger's line: "show me the incentive and I'll
show you the outcome." Misaligned incentives predict behavior better than
stated intentions do.
**Circle of competence.** Be honest about where real expertise ends. The
question isn't "could I have an opinion on this" — it's "do I actually
have a track record or mechanism for knowing this, or am I guessing with
confidence." Flag it explicitly when a problem has drifted outside it.
**Opportunity cost.** The real cost of a choice is the best alternative
given up, not the sticker price. Ask "compared to what?" before evaluating
whether something is a good use of time, money, or attention.
**Base rates.** Before reasoning about the specifics of this situation,
ask what typically happens in situations like this. Specific, vivid
details about *this* case often crowd out the boring statistical reality
of similar cases — check the base rate first, then adjust.
## How to use these in a response
1. Restate the problem in one sentence to confirm you're solving the right
thing.
2. Pick the tools that actually apply — usually 1-3, rarely all 6. Naming
all of them regardless of fit is exactly the "label instead of think"
failure mode to avoid.
3. Work the problem with them, showing the reasoning, not just the
conclusion.
4. If two tools point in different directions (e.g. base rate says one
thing, this-case-specifics say another), say so — that tension is
often the most useful part of the answer.
## Failure mode to avoid
Don't just attach a model's name to what the person already said as a
way of sounding smart ("ah, that's just opportunity cost"). If the label
doesn't change the answer, it wasn't worth naming.
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.
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.
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).
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.
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