short answer
Mental models simplify and help you understand the world. The most useful mental models do not tell you what to think. They train you how to think by giving you better ways to prioritize, question assumptions, see blind spots, and choose what matters.
watch the video
This article is adapted from my video, 10 Mental Models Explained. Watch the video if you want the full walkthrough of all 10 models and how they connect to problem-solving, business decisions, and everyday thinking.
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the 10-second version
mental model | what it helps you do | use this when | question to ask |
|---|---|---|---|
80/20 rule | prioritize the few actions that create most results | everything feels equally important | Which 20% of effort creates 80% of the outcome? |
theory of constraints | find the bottleneck slowing the whole system | you are busy but not making progress | What is the weakest part of this system? |
first principles | break a problem down to fundamental truths | the situation feels too complex or noisy | What is true here, and what am I assuming? |
Occam’s razor | choose the explanation with fewer assumptions | you have too many theories | What is the simplest explanation that fits? |
Hock principle | use simple principles instead of complex rules | people are overcomplicating execution | What simple purpose or principle should guide behavior? |
interest-based counting | see the real players and incentives | people may not be acting alone | Whose interests are actually aligned here? |
via negativa | improve by subtracting what hurts you | adding more is not working | What should I remove? |
inversion | solve backward from what you want to avoid | you feel stuck going forward | What would guarantee failure? |
relativity | look from outside the system | you cannot see the full picture | What can an observer see that I cannot? |
velocity vs speed | move in the right direction, not just faster | there is pressure to hurry | Am I moving toward the goal or just moving fast? |
the real problem
The hard part of mental models is rarely understanding the definition.
The hard part is knowing how to use them.
When I first started learning mental models, that was the most difficult thing for me. I could read the model. I could understand the example. But I did not always know how to put the models together or apply them to daily life.
That is why this article is organized around use.
The first five mental models help you simplify complexity:
80/20 rule.
Theory of constraints.
First principles.
Occam’s razor.
Hock principle.
The next five help you see reality differently:
Interest-based counting.
Via negativa.
Inversion.
Relativity.
Velocity vs speed.
Mental models are frameworks and structures that help us understand the world. They shape how we think and how we make decisions.
But they are for how to think, not what to think.
The point is not to memorize clever concepts. The point is to have better questions ready when the world gets messy.
For my latest updates on the difference between mental models vs. frameworks, watch Mental Models vs Frameworks.
model 1: 80/20 rule
The 80/20 rule is a rule of uneven distribution.
Roughly 80% of your results often come from 20% of your efforts.
Since everyone has only 24 hours a day, the people who can prioritize and focus their efforts on the right things are usually able to achieve more.
In the video, I say this rule was drilled into my head from my management consulting background. It became the first filter I applied to any problem:
How do I prioritize?
How do I structure the problem?
Which part matters most?
You can use it in a very simple way.
Take your to-do list and identify the 20% of tasks that will give you 80% of the results in terms of getting you closer to your goal.
Most of us have a tendency to focus on the easy things on our to-do list. It feels good to cross things off quickly. But those things are usually not the ones that take us closer to our goals.
Momentum matters, but momentum alone is not the same as progress.
Use the 80/20 rule when you need to ask:
model 2: theory of constraints
The natural question after the 80/20 rule is:
That is where the theory of constraints helps.
The theory of constraints says that a system is only as strong as its weakest part. For the system to succeed, you need to identify the bottleneck: the constraint where the flow is slowed or stopped.
The bottleneck might be small, but it can have disproportionate impact on the system as a whole.
In the video, I use the example of when I first started my business. I felt really stuck. I was doing all these things but not seeing results, and I did not know why.
One question helped:
For me, the bottleneck was talking to real users with the problem I was trying to solve.
I knew I had to get market validation, but I made up all kinds of excuses:
Meanwhile, I was spending time on the 80% that did not really create results: building a beautiful brand guide, making a beautiful website, finding the perfect business name.
The bottleneck was not branding.
The bottleneck was talking to people who had the problem of not being able to articulate their business, so I could understand whether they had message-market fit.
Once I did that, I got feedback that helped me make effective decisions and know where to go with the business.
Looking for the bottleneck is one of the best ways to find the 20% of effort that gives you 80% of the impact.
model 3: first principles
First principles thinking helps you train your brain to think from the fundamental level.
When you face a complex situation, break it down into:
Fundamental truths.
Assumptions.
The assumptions are usually what lead us astray.
To solve something complex, you want to understand the essence of the problem, then reason up from there.
Charlie Munger has a simple way of reminding us how to do this:
For example, if you want to improve profitability, one first principle from business is:
It does not matter what the industry is. It does not matter what size the business is. Profit comes back to those two components:
Revenue.
Cost.
Of course, the details can still be complicated. There may be interdependencies. There may be many reasons revenue is not growing or cost is too high.
But first principles give you a place to begin.
Ask:
model 4: Occam’s razor
Occam’s razor says that when there are multiple explanations for a situation, the simplest explanation is more likely to be true.
In practice, it means:
This connects directly to first principles.
If first principles help you separate truths from assumptions, Occam’s razor helps you avoid building a decision on too many assumptions.
When a project is failing, you might have five theories:
The audience is wrong.
The offer is unclear.
The timing is bad.
The team is misaligned.
The strategy is broken.
Some of those may be true. But before you build a complicated story, ask which explanation requires the fewest assumptions.
Maybe people simply do not understand the offer.
Maybe the decision owner was never clear.
Maybe the work was never scoped properly.
This does not mean the simplest answer is always correct. It means the simplest answer that fits the evidence should be taken seriously before you reach for a more complicated one.
model 5: Hock principle
The Hock principle comes from Dee Hock, founder and former CEO of Visa.
The idea is:
You can feel this inside organizations.
When people are guided by a clear purpose and simple principles, they can make intelligent decisions without needing a rule for every possible situation.
But when people are buried under complex rules and regulations, they often stop thinking. They follow the rule even when the rule creates a worse outcome.
This is why organizations that treat people like kids who do not understand what is going on can hurt themselves in the long run.
Use the Hock principle when you work with others:
You can also use it on yourself.
Hold yourself to a higher standard with the line often attributed to Einstein:
model 6: interest-based counting
Interest-based counting comes from game theory.
Imagine a poker table with five people sitting around it. There are chips. There are cards ready to be dealt.
How many players are there?
The obvious answer is five.
But that misses something crucial for decision-making: the interests at hand.
If two players form an alliance and agree to share winnings and losses, the way they play the game will be different. If you judge what is happening as if there are five separate interests, your understanding will be distorted.
The house also has an opposing interest.
So how many players are there?
It is more complicated than the number of people sitting at the table.
Use this when you are negotiating, looking for a promotion, competing for resources, or trying to understand workplace dynamics.
Ask:
The number of people is not always the same as the number of interests.
model 7: via negativa
Via negativa is Latin for focusing on what something is not.
A practical version of this advice is:
To succeed, avoid doing something stupid.
When something is not working, most of us ask:
Adding can help. But sometimes the better move is subtraction.
What people often underestimate is how much progress can come from removing what creates drag.
For example, improving your information diet may have less to do with adding more useful information and more to do with removing information that makes your thinking noisy.
The same principle can apply to meetings, habits, strategy, health, writing, and decision-making.
Ask:
Via negativa helps you improve by subtraction.
model 8: inversion
Most of us are trained to think from the beginning to the end.
Inversion asks you to think backward.
Instead of only asking:
Ask:
This is powerful because it reveals obstacles you may not see when you only think forward.
If you want a better presentation, ask:
If you want a better decision, ask:
If you want a clearer strategy, ask:
You can also combine inversion with via negativa:
Inversion is especially useful when you feel stuck because it gives your brain a different entrance into the problem.
model 9: relativity
Relativity gives us the idea that we cannot fully understand a system that we are part of.
In the video, I use the airplane example.
If you are on a plane, you do not feel like you are moving at 900 kilometers an hour because you are moving at the same speed as the plane.
But an observer can see how fast the plane is moving because they are not part of that system.
This applies to everyday life more often than we want to admit.
There are many moments where we cannot see the fuller picture because we are inside the system.
That is why you should not be too quick to write off different perspectives.
When people say something you disagree with, that is often where the gold is. It may reveal a blind spot in your understanding of the world.
Ask:
Relativity helps you remember that your view is always from somewhere.
model 10: velocity vs speed
Our society loves to glorify going fast.
But speed and velocity are not the same thing.
Speed is how fast you go.
Velocity is how fast you go to get somewhere.
That difference matters.
You can move backward really fast, but that does not help you get where you want to go.
Use this model whenever you feel pressure to hurry.
Ask:
This is especially useful for ambitious people because fast movement can feel productive even when the direction is wrong.
Velocity reminds you to care about direction, not just pace.
try this
Use this exercise the next time you feel stuck, overwhelmed, or unclear.
If you only use one question, use this:
What is the one thing I need to do but I am putting off?
That question often reveals the bottleneck.
common mistakes
Collecting mental models without applying them. Mental models are only useful when they change the questions you ask and the decisions you make.
Using the wrong model for the problem. If the issue is prioritization, use 80/20 or theory of constraints. If the issue is perspective, use relativity or inversion.
Confusing simple with simplistic. The goal is to remove unnecessary assumptions, not flatten the problem until it becomes inaccurate.
Moving fast without checking direction. Speed feels good, but velocity asks whether the movement is taking you where you actually want to go.
🧪 why mental models?
Mental models help because your brain needs compression.
Most problems have too many details to hold at once. A good mental model gives you a structure that reduces the noise without removing what matters.
The 80/20 rule and theory of constraints help you prioritize. First principles and Occam’s razor help you simplify. The Hock principle helps you replace overcomplicated rules with clearer purpose and principles.
Interest-based counting, via negativa, inversion, relativity, and velocity vs speed help you see what your default perspective might miss.
The value is not in memorizing the names.
The value is in having better questions available when you need them:
That is how mental models become practical tools for clear thinking.
if you enjoyed this…
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