This is a book summary of The Great Mental Models Volume 1: General Thinking Concepts by Shane Parrish of Farnam Street (Amazon).
Quick Housekeeping:
- All content in quotation marks is from the author unless otherwise stated.
- All content not in quotation marks is paraphrased from original quotes.
- I’ve added emphasis in bold for readability/skimmability.
Book Summary Contents: Click a link here to jump to a section below
- About Farnam Street & The Book
- What are Mental Models?
- The Map is not the Territory
- Circle of Competence
- First Principles Thinking
- Second-Order Thinking
- Thought Experiment
- Inversion
An Intro to General Thinking Concepts: The Great Mental Models Volume 1 by Farnam Street (Book Summary)
About Farnam Street & The Great Mental Models
“Farnam Street is devoted to helping you develop an understanding of how the world really works, make better decisions, and live a better life. We address such topics as mental models, decision-making, learning, reading, and the art of living.”
About Farnam Street (founded by Shane Parrish):
- “In a world full of noise, Farnam Street is a place where you can step back and think about time-tested ideas while asking yourself questions that lead to meaningful understanding. We cover ideas from science and the humanities that will not only expand your intellectual horizons but also help you connect ideas, think in multidisciplinary ways, and explore meaning.”
- “I started writing about my learnings, the result being the Farnam Street website. The last eight years of my life have been devoted to identifying and learning the mental models that have the greatest positive impact, and trying to understand how we think, how we update, how we learn, and how we can make better decisions.”
Shane Parrish acknowledges that he’s standing on the shoulders of giants:
- “This book wouldn’t be possible without the insights of others. The goal of Farnam Street is to master the best of what other people have figured out. True to this mission, everything in here began with someone else.”
- “The ideas in these volumes are not my own, nor do I deserve any credit for them … I’ve only curated, edited, and shaped the work of others before me.”
- “These pages are filled with ideas from many great minds. It’s only fair to point out that any idea you found in this book comes from someone else.”
About The Great Mental Models:
- “When I first started learning about multidisciplinary thinking there was no source of collected wisdom—no place where I could find the big ideas from multiple disciplines in one place. This book, and indeed, this series, is meant to bring some of the big invariant ideas into the world to help us better understand the world we live in and how it interconnects.“
- “The Great Mental Models Project is a labor of love to help equalize opportunity in the world by making a high-quality, multidisciplinary, interconnected education free and available to everyone.”
- “In identifying the Great Mental Models we have looked for elementary principles, the ideas from multiple disciplines that form a time-tested foundation.”
What are Mental Models?
“When you learn to see the world as it is, and not as you want it to be, everything changes. The solution to any problem becomes more apparent when you can view it through more than one lens. You’ll be able to spot opportunities you couldn’t see before, avoid costly mistakes that may be holding you back, and begin to make meaningful progress in your life. That’s the power of mental models.”
On mental models:
- “Mental models describe the way the world works. They shape how we think, how we understand, and how we form beliefs. Largely subconscious, mental models operate below the surface. We’re not generally aware of them and yet they’re the reason when we look at a problem we consider some factors relevant and others irrelevant. They are how we infer causality, match patterns, and draw analogies. They are how we think and reason.”
- “A mental model is simply a representation of how something works. We cannot keep all of the details of the world in our brains, so we use models to simplify the complex into understandable and organizable chunks. Whether we realize it or not, we then use these models every day to think, decide, and understand our world.”
- “Being able to draw on a repertoire of mental models can help us minimize risk by understanding the forces that are at play. Likely consequences don’t have to be a mystery.”
It all comes down to better contact with reality:
- “Removing blind spots means thinking through the problem using different lenses or models. When we do this the blind spots slowly go away and we gain an understanding of the problem. We’re much like the blind men in the classic parable of the elephant, going through life trying to explain everything through one limited lens.”
- “The more lenses used on a given problem, the more of reality reveals itself. The more of reality we see, the more we understand. The more we understand, the more we know what to do.”
- “We need to work hard at synthesizing across the borders of our knowledge, and most importantly, synthesizing all of the ideas we learn with reality itself.”
Our failures to update from interacting with reality spring primarily from three things:
- Not having the right perspective or vantage point: “We have a hard time seeing any system that we are in.”
- Ego-induced denial: “Many of us tend to have too much invested in our opinions of ourselves to see the world’s feedback—the feedback we need to update our beliefs about reality.”
- Distance from the consequences of our decisions: “The further we are from the results of our decisions, the easier it is to keep our current views rather than update them.”
Ultimately, the goal is to build a latticework of mental models in your head:
- “Exactly the same sort of pattern that graces backyards everywhere, a lattice is a series of points that connect to and reinforce each other. The Great Models can be understood in the same way—models influence and interact with each other to create a structure that can be used to evaluate and understand ideas.”
- “Munger has a way of thinking through problems using what he calls a broad latticework of mental models. These are chunks of knowledge from different disciplines that can be simplified and applied to better understand the world. The way he describes it, they help identify what information is relevant in any given situation, and the most reasonable parameters to work in.”
- “A latticework is an excellent way to conceptualize mental models, because it demonstrates the reality and value of interconnecting knowledge. The world does not isolate itself into discrete disciplines. We only break it down that way because it makes it easier to study it. But once we learn something, we need to put it back into the complex system in which it occurs. We need to see where it connects to other bits of knowledge, to build our understanding of the whole. This is the value of putting the knowledge contained in mental models into a latticework.”
The Map is not the Territory
“The map of reality is not reality. Even the best maps are imperfect. That’s because they are reductions of what they represent.”
About the map is not the territory mental model:
- “In other words, the description of the thing is not the thing itself. The model is not reality. The abstraction is not the abstracted.”
- “The only way we can navigate the complexity of reality is through some sort of abstraction.”
- “Models are most useful when we consider them in the context they were created.”
- “We must use some model of the world in order to simplify it and therefore interact with it. We cannot explore every bit of territory for ourselves. We can use maps to guide us, but we must not let them prevent us from discovering new territory or updating our existing maps.”
- “We can’t use maps as dogma. Maps and models are not meant to live forever as static references. The world is dynamic. As territories change, our tools to navigate them must be flexible to handle a wide variety of situations or adapt to the changing times. If the value of a map or model is related to its ability to predict or explain, then it needs to represent reality. If reality has changed the map must change.”
In order to use a map or model as accurately as possible, we should take three important considerations into account:
- Reality is the ultimate update: “We can and should update them based on our own experiences in the territory. That’s how good maps are built: feedback loops created by explorers.”
- Consider the cartographer: “Maps are not purely objective creations. They reflect the values, standards, and limitations of their creators.”
- Maps can influence territories.
The map is not the territory watch-outs:
- “We run into problems when our knowledge becomes of the map, rather than the actual underlying territory it describes.”
- “In using maps, abstractions, and models, we must always be wise to their limitations. They are, by definition, reductions of something far more complex. There is always at least an element of subjectivity, and we need to remember that they are created at particular moments in time.”
- “A map captures a territory at a moment in time. Just because it might have done a good job at depicting what was, there is no guarantee that it depicts what is there now or what will be there in the future.”
Circle of Competence
“When ego and not competence drives what we undertake, we have blind spots. If you know what you understand, you know where you have an edge over others. When you are honest about where your knowledge is lacking you know where you are vulnerable and where you can improve. Understanding your circle of competence improves decision-making and outcomes.”
About the circle of competence mental model:
- “Within our circles of competence, we know exactly what we don’t know. We are able to make decisions quickly and relatively accurately. We possess detailed knowledge of additional information we might need to make a decision with full understanding, or even what information is unobtainable. We know what is knowable and what is unknowable and can distinguish between the two.”
- “Critically, we must keep in mind that our circles of competence extend only so far. There are boundaries on the areas in which we develop the ability to make accurate decisions. In any given situation, there are people who have a circle, who have put in the time and effort to really understand the information. It is also important to remember that no one can have a circle of competence that encompasses everything. There is only so much you can know with great depth of understanding. This is why being able to identify your circle, and knowing how to move around outside of it, is so important.”
- “There is no shortcut to understanding. Building a circle of competence takes years of experience, of making mistakes, and of actively seeking out better methods of practice and thought.”
Three key practices needed in order to build and maintain a circle of competence:
- Curiosity and a desire to learn: “Learning comes when experience meets reflection. You can learn from your own experiences. Or you can learn from the experience of others, through books, articles, and conversations. Learning everything on your own is costly and slow. You are one person. Learning from the experiences of others is much more productive. You need to always approach your circle with curiosity, seeking out information that can help you expand and strengthen it.”
- Monitoring: “You need to monitor your track record in areas which you have, or want to have, a circle of competence. And you need to have the courage to monitor honestly so the feedback can be used to your advantage.”
- Feedback: “You must occasionally solicit external feedback. This helps build a circle, but is also critical for maintaining one.”
Circle of competence watch-outs:
- “It is extremely difficult to maintain a circle of competence without an outside perspective. We usually have too many biases to solely rely on our own observations. It takes courage to solicit external feedback, so if defensiveness starts to manifest, focus on the result you hope to achieve.”
- “One of the essential requirements of a circle of competence is that you can never take it for granted. You can’t operate as if a circle of competence is a static thing, that once attained is attained for life. The world is dynamic. Knowledge gets updated, and so too must your circle.”
First Principles Thinking
“First principles thinking is one of the best ways to reverse-engineer complicated situations and unleash creative possibility. Sometimes called reasoning from first principles, it’s a tool to help clarify complicated problems by separating the underlying ideas or facts from any assumptions based on them. What remain are the essentials.”
About the first principles thinking mental model:
- “First principles thinking identifies the elements that are, in the context of any given situation, non-reducible.”
- “Reasoning from first principles allows us to step outside of history and conventional wisdom and see what is possible. When you really understand the principles at work, you can decide if the existing methods make sense. Often they don’t.”
- “Thinking through first principles is a way of taking off the blinders. Most things suddenly seem more possible.”
- “If we want to identify the principles in a situation to cut through the dogma and the shared belief, there are two techniques we can use: Socratic questioning and the Five Whys.”
Socratic questioning can be used to establish first principles through stringent analysis:
- Clarifying your thinking and explaining the origins of your ideas: Why do I think this? What exactly do I think?
- Challenging assumptions: How do I know this is true? What if I thought the opposite?
- Looking for evidence: How can I back this up? What are the sources?
- Considering alternative perspectives: What might others think? How do I know I am correct?
- Examining consequences and implications: What if I am wrong? What are the consequences if I am?
- Questioning the original questions: Why did I think that? Was I correct? What conclusions can I draw from the reasoning process?
The goal of the Five Whys is to land on a “what” or “how”:
- “It is not about introspection, such as ‘Why do I feel like this?’ Rather, it is about systematically delving further into a statement or concept so that you can separate reliable knowledge from assumption. If your ‘whys’ result in a statement of falsifiable fact, you have hit a first principle. If they end up with a ‘because I said so’ or ‘it just is’, you know you have landed on an assumption that may be based on popular opinion, cultural myth, or dogma. These are not first principles.”
Second-Order Thinking
“Almost everyone can anticipate the immediate results of their actions. This type of first-order thinking is easy and safe but it’s also a way to ensure you get the same results that everyone else gets. Second-order thinking is thinking farther ahead and thinking holistically.“
About the second-order thinking mental model:
- “It requires us to not only consider our actions and their immediate consequences, but the subsequent effects of those actions as well. Failing to consider the second- and third-order effects can unleash disaster.”
- “We don’t make decisions in a vacuum and we can’t get something for nothing. When making choices, considering consequences can help us avoid future problems. We must ask ourselves the critical question: And then what? Consequences come in many varieties, some more tangible than others. Thinking in terms of the system in which you are operating will allow you to see that your consequences have consequences.“
- “Very often, the second level of effects is not considered until it’s too late. This concept is often referred to as the ‘Law of Unintended Consequences’ for this very reason.”
- “Any comprehensive thought process considers the effects of the effects as seriously as possible.”
- “High degrees of connections make second-order thinking all the more critical, because denser webs of relationships make it easier for actions to have far-reaching consequences.”
Two areas where second-order thinking can be used to great benefit:
- Prioritizing long-term interests over immediate gains: “Being aware of second-order consequences and using them to guide your decision-making may mean the short term is less spectacular, but the payoffs for the long term can be enormous. By delaying gratification now, you will save time in the future.”
- Constructing effective arguments.
Second-order thinking watch-outs:
- “Second-order thinking, as valuable as it is, must be tempered in one important way: You can’t let it lead to the paralysis of the Slippery Slope Effect, the idea that if we start with action A, everything after is a slippery slope down to hell, with a chain of consequences B, C, D, E, and F.”
- “Second-order thinking needs to evaluate the most likely effects and their most likely consequences, checking our understanding of what the typical results of our actions will be. If we worried about all possible effects of effects of our actions, we would likely never do anything, and we’d be wrong. How you’ll balance the need for higher-order thinking with practical, limiting judgment must be taken on a case-by-case basis.”
Thought Experiment
“Thought experiments can be defined as ‘devices of the imagination used to investigate the nature of things.'”
About the thought experiment mental model:
- “Thought experiments are powerful because they help us learn from our mistakes and avoid future ones. They let us take on the impossible, evaluate the potential consequences of our actions, and re-examine history to make better decisions. They can help us both figure out what we really want, and the best way to get there.”
- “Thought experiments tell you about the limits of what you know and the limits of what you should attempt. In order to improve our decision-making and increase our chances of success, we must be willing to probe all of the possibilities we can think of.”
- “Its chief value is that it lets us do things in our heads we cannot do in real life, and so explore situations from more angles than we can physically examine and test for.”
- “Thought experiments are more than daydreaming. They require the same rigor as a traditional experiment in order to be useful.”
- “One of the real powers of the thought experiment is that there is no limit to the number of times you can change a variable to see if it influences the outcome.”
Much like the scientific method, a thought experiment generally has the following steps:
- Ask a question.
- Conduct background research.
- Construct hypothesis.
- Test with (thought) experiments.
- Analyze outcomes and draw conclusions.
- Compare to hypothesis and adjust accordingly (new question, etc.).
A few areas in which thought experiments are tremendously useful:
- Imagining physical impossibilities.
- Re-imagining history.
- Intuiting the non-intuitive.
Inversion
“The root of inversion is ‘invert,’ which means to upend or turn upside down. As a thinking tool it means approaching a situation from the opposite end of the natural starting point.”
About the inversion mental model:
- “Most of us tend to think one way about a problem: forward. Inversion allows us to flip the problem around and think backward.”
- “Whatever angle you choose to approach your problem from, you need to then follow with consideration of the opposite angle. Think about not only what you could do to solve a problem, but what you could do to make it worse—and then avoid doing that, or eliminate the conditions that perpetuate it.”
Two approaches to applying inversion in your life:
- “Start by assuming that what you’re trying to prove is either true or false, then show what else would have to be true.”
- “Instead of aiming directly for your goal, think deeply about what you want to avoid and then see what options are left over.”
Psychologist Kurt Lewin’s process (force field analysis):
- Identify the problem.
- Define your objective.
- Identify the forces that support change towards your objective.
- Identify the forces that impede change towards the objective.
- Strategize a solution! This may involve both augmenting or adding to the forces in step 3, and reducing or eliminating the forces in step 4.
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