Free Field Library

The decisions that shape your life
deserve better tools.

A structured library of mental models, cognitive biases, and decision frameworks. Written for real decisions — career, money, relationships, business — not MBA classrooms.

Explore Mental Models → Get a Quick Answer
Mental Models

One page per mental model, cognitive bias, or decision tool. Each one explains the concept, shows where it fails you, and connects it to a real decision type. Structured for fast reading and direct answers.

Common Questions

Facing a specific decision right now? These pages answer the questions people actually type — job offers, quitting, relocating, renting vs buying, ending relationships — directly and without padding.

Decision Guides

Some decisions arrive on a predictable schedule: appraisal season, year-end finances, MBA applications. These guides apply the right framework at the right moment — before the pressure peaks.

Mental Models

The frameworks behind better decisions

The most useful mental models and cognitive biases, one page each. Each page answers your question directly and shows how the framework applies to decisions you are probably facing right now.

Field Note 01 Mental Model
Regret Minimization Framework
Jeff Bezos's decision tool. Project yourself to 80, look back, and ask which choice you would regret not making. The clearest mental model for career and life pivots.
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Field Note 02 Decision Tool
The Pre-Mortem
Before a decision, imagine it has already failed. Now work backwards. Gary Klein's technique forces your brain to surface risks it would otherwise suppress.
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Field Note 03 Cognitive Bias
Confirmation Bias
You already know what you want to decide. Now you're looking for evidence to back it up. Confirmation bias is why smart people make bad decisions with good information.
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Field Note 04 Cognitive Bias
Sunk Cost Fallacy
The money is gone. The years are spent. Staying because you've already invested is not loyalty — it's a thinking error. How to recognise and escape the sunk cost trap.
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Field Note 05 Mental Model
Inversion Thinking
Charlie Munger's signature move: instead of asking how to succeed, ask what would guarantee failure — then avoid it. Inversion is one of the most useful habits in high-stakes decisions.
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Field Note 06 Decision Tool
The 10/10/10 Rule
Suzy Welch's framework for breaking out of short-term thinking. How will you feel about this decision in 10 minutes, 10 months, and 10 years? Simple. Surprisingly hard to argue with.
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Field Note 07 Cognitive Bias
Loss Aversion
Kahneman and Tversky showed that losing something hurts roughly twice as much as gaining the same thing feels good. This asymmetry drives most risk avoidance — and most financial mistakes.
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Field Note 08 Mental Model
First Principles Thinking
Break the problem down to its fundamental truths and reason up from there. Elon Musk's most quoted mental model, explained without the startup mythology.
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View all mental models →

Decision Guides

Some decisions arrive on a schedule

Appraisal season. MBA applications. Year-end finances. These guides are written ahead of those moments so the framework is ready before the pressure arrives.

Career
Got your appraisal letter? Now is when most people make the wrong call.
May is when offer letters spike and bad decisions follow. A structured guide to the job-switch decision using the Regret Minimization Framework and Status Quo Bias — the two frameworks that matter most right now.
Read the guide
Education
Should I do an MBA? The decision most people outsource to the wrong people.
MBA application windows open in July. A framework-first guide to the MBA decision that does not start with rankings.
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Financial
The year-end financial audit. What to decide before December closes.
Tax planning, investment rebalancing, and the year-end money decisions that compound or erode your financial position.
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Common Questions

Facing a real decision right now?

These pages answer one question directly — the question most people are typing when a decision is live. No preamble. A framework you can apply today.

How do I decide between two job offers?
When both offers look good, the comparison becomes the trap. A framework for the variables that actually matter.
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Should I quit my job to start a business?
The runway calculation, the reversibility test, and the bias that keeps most people stuck for years longer than they need to be.
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How do I overcome decision paralysis?
Paralysis is not a lack of information. It is usually a specific bias or fear in disguise. How to identify which one is running.
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Should I buy or rent a house?
The question is almost always framed wrong. The real comparison is not financial — it is about flexibility versus stability.
Get the answer
See all common questions →

About this site

Built alongside a book, designed for the person facing an actual decision.

Every framework on this site comes from the same intellectual work that is going into the Decisions Matter book. The site pages are public, free, and written to be useful in one sitting. The book is the deeper treatment -- the how, why, and history behind each model, with a 6-step decision system that ties everything together.

This is not a self-help project. The frameworks here are the same ones used in corporate strategy, investment analysis, and military planning -- brought down to the level where people actually live: career choices, financial decisions, relationship crossroads, and business pivots.

About Harish Keswani Run a decision through the tool →