80 Useful Mental Models

I strongly believe that one of the most valuable things we can do as creatures of thought is self-reflection: taking a little time out every once in a while to cross-examine the fundamental models we habitually use to process the world and make decisions. Hands down, the best article I have read on this topic is Mental Models I Find Repeatedly Useful. It provides short, crisp descriptions of around 190 big ideas encompassing everything from philosophy and reasoning to investing, managing, marketing and productivity - all things that businesspeople can use for sharper thinking.

Drawing on the Medium piece and a couple of other similar articles for inspiration, this summary article represents a list of 80 well known models (in no particular order) that I find myself coming back to time and again. I fully expect that many, maybe most, of these models won't be new to you; however, it can still be good to revisit certain ideas, principles and frameworks in case they spark something. Maybe you completely forgot that some of these models existed, but hopefully there will be a few unfamiliar ones too.

These 80 models were selected either because they have direct value or because they provide a basic template, blueprint or starting point that is useful for injecting into conversation or generally adapting in some way.

I don't mean to imply these are the best models out there or the only ones I would recommend; this is simply a collection of core concepts that I actually use (in business and in life), and not just ones that sound good on paper but then get pushed aside or forgotten amid the hustle and bustle of daily life.

Why not have a go at this self-reflection exercise for yourself... what mental models do you return to most often?

1. The Map is Not the Territory - This is a popular metaphor that illustrates the difference between belief and reality. Our mental model or map of reality, however accurate we believe it may be, is not reality. And no two people carry identical maps.

2. Heuristic - A mental shortcut or rule of thumb that offers something more practical than theoretically perfect. E.g., “Measure twice, cut once” is a heuristic, as are many of the other mental models in this list.

3. The Law of Non-Contradiction - “Contradictory statements cannot both be true in the same sense at the same time.” First formalised by Aristotle, this foundational law of logic is fundamental to working out everything we believe to be true or false in our lives, whether we realise it or not.

4. The Matter of Degree Versus Kind (Continuum vs. Category) - Wiki: continuum theories or models explain variation as involving gradual quantitative transitions without abrupt changes or discontinuities. In contrast, categorical theories or models explain variation using qualitatively different states.

5. Maslow’s Hammer - Named after the psychologist Abraham Maslow, there are several variations of the Maslow’s Hammer quote, but a common one goes like this: “If the only tool you have is a hammer, everything looks like a nail.” In other words, if you only have a few tools or mental models, you will be prone to viewing situations through a very narrow lens—attempting to make each situation fit your model.

6. Universal Principles - As articulated by Stephen Covey, universal principles are core human values that are self-evident and understood by children and adults in all countries on earth, regardless of race, religion, or culture. These include concepts such as respect, fairness, integrity, human dignity, service, humility, and growth. Covey’s 7 Habits of Highly Effective People is anchored in these principles.

7. Critical Thinking - This involves evaluating ideas based on reason and logic, rather than rushing to accept or deny something based purely on emotion, bias, prejudice, gut feel, etc. Critical thinking is a mental buffer that gives us time to ensure we prevent as many false things as possible from taking up space in our brains, and helps us to believe as many true things as possible, while accepting that any of our most cherished convictions are subject to revision at any time. It is not the same thing as reckless negativity, criticism, pessimism, or cynicism.

8. Black and White Thinking - This is a type of cognitive distortion also known as all-or-nothing thinking. It happens when the thinker goes towards the extreme end, ignoring or failing to see any middle ground or grey area. “Always,” “never,” “everyone,” “no one,” “everything,” “nothing,” are common hallmarks of this thinking.

9. The Scientific Method - Wiki: A method of procedure that has characterised natural science since the 17th century, consisting of systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.

10. The Socratic Method - Named after Socrates, this is a questioning technique designed to scruitise claims, reveal underlying assumptions, and draw out beliefs or ideas in a non-confrontational manner. It is widely used by teachers and lawyers.

11. Principle of Falsification - The concept of falsifiability is one of the most important ideas in science. Scientific theories can never be proven right in an absolute sense, but they can be proven wrong through well-designed testing. Therefore, hypotheses that survive enough rigorous testing can be advanced to the status of “fact.” Hypotheses that can't be tested can't be advanced very far.

12. Burden of Proof - Wiki: Burden of proof can define the duty placed upon a party to prove or disprove a disputed fact, or it can define which party bears this burden.

13. Prototype Theory - This refers to a kind of graded categorisation used in cognitive science, which can be contrasted with attempts to provide categorical definitions. For example, instead of trying to define what a “bird” is through conventional analysis, people might be asked to rate how prototypical certain bird species are. A robin might score 7. A penguin might score 4, and so on. This is a way of working out which features from a category best represent that category in people’s minds. (Related concept: Archetypes.)

14. The Reasonable Person - This refers to the legal construct in which a jury is asked to judge someone’s actions against the standard of a “reasonable person,” which is a construct that can be applied to many other situations.

15. Occam’s Razor - This scientific principle states that among competing hypotheses, the simplest explanation—the one requiring the fewest number of assumptions—is most likely to be correct. This is connected to abductive reasoning—one of three main types of reasoning that could be summarised as “inference to the best explanation.” In short: what is most likely to be true has priority over what could be true.

16. Meme - Wiki: an element of a culture or system of behaviour passed from one individual to another by imitation or other non-genetic means.

17. Entropy (The second law of thermodynamics) - In general use, entropy often refers to the observation that systems, especially highly complex systems, will run towards a state of disorder or decay unless otherwise acted upon.

18. Bias - Bias is a conscious or unconscious inclination to present or view information or actions in a certain way, often contrasted with being fair or objective. The political bent of an institution can be especially important to consider when evaluating news and content.

19. Authority Bias - The tendency to attribute greater accuracy to the opinion of an authority figure (unrelated to its content) and be more influenced by that opinion. There is a common form of logical fallacy known as an “argument from authority” in which a person relies on the status or reputation of a leader, expert, or institution to advance an argument.

20. Anecdotal Evidence vs. Empirical Evidence - Anecdotal evidence is evidence from anecdotes (e.g., a witness’s recollection of a crime). Empirical evidence is evidence from observation and experimentation (e.g., DNA testing), which is generally considered superior to anecdotal evidence.

21. Replication - In a scientific context, replication refers to the reproducibility of an experiment. It’s not uncommon to see the results of a single study presented in the media as though it is “fact” when this kind of confidence can only be clearly established by having independent parties repeatedly reproduce the same results.

22. Correlation Doesn’t Imply Causation - Just because two events are connected or correlated, it doesn’t mean one event necessarily caused the other event.

23. Normal Distribution - Also known as a “bell curved” distribution or Gaussian distribution, this is a very important concept in statistics. Basically, it means that in a given set of data, the majority of the examples fall within a certain range around the middle (about 68%), while fewer and fewer examples are found the farther one deviates from the mid point. IQ, height, and weight are all normally distributed.

24. Regression to the Mean - Wiki: the phenomenon that if a variable is extreme on its first measurement, it will tend to be closer to the average on its second measurement.

25. Control Group / Randomised Control Trial (RTC) / Double Blind - Wiki: RTC is an experiment which aims to reduce bias when testing a new treatment. The people participating in the trial are randomly allocated to either the group receiving the treatment under investigation or to a group receiving standard treatment (or placebo treatment) as the control. The Double Blind is a highly regarded trial in which neither the participants nor the researchers know which participants belong to the control group, nor the test group.

26. The Placebo Effect - Medicinenet: A remarkable phenomenon in which a placebo — a fake treatment, an inactive substance like sugar, distilled water, or saline solution — can sometimes improve a patient's condition simply because the person has the expectation that it will be helpful.

27. Availability Heuristic - A mental shortcut that relies on immediate examples that come to mind, which can bias decision making.

28. Loss Aversion - Wiki: The tendency for people to strongly prefer avoiding losses than acquiring gains.

29. Negativity Bias - Humans tend to have greater sensitivity to unpleasant news and events.

30. The Magic Ratio - Connected to negativity bias, the magic ratio is 5:1 positive to negative interactions in relationships. In other words, humans need several times more positive events to cancel out a single negative event. Credited to Dr. John Gottman, the application of this ratio is said to predict divorce with a high degree of accuracy.

31. The Curse of Knowledge - In essence, the more you know, the less clearly you communicate, because you will tend to assume that other people have the same knowledge and know the same words.

32. Ethos, Pathos, and Logos (Modes of Persuasion) - These three famous rhetorical devices were introduced by Aristotle. Ethos: appeal to credibility or character (especially if you are an expert or have special qualifications related to the subject). Pathos: appeal to emotion (especially with story and metaphor). Logos: appeal to reason or logic (especially with evidence, facts, and statistics).

33. Six Principles of Influence - Coined by Dr. Robert Cialdini, the six principles of influence are: Reciprocity (people want to return favours); Commitment and Consistency (people want to honour things they have agreed to); Social Proof (people like to know what others think); Authority (people will tend to trust authority figures); Liking (people are more likely to trust messages from sources they like); Scarcity (people want rare items).

34. FOMO - Wiki: Fear of missing out or FOMO is "a pervasive apprehension that others might be having rewarding experiences from which one is absent."

35. Confirmation Bias - Wiki: the tendency to interpret new evidence as confirmation of one's existing beliefs or theories.

36. The Golden Mean - Coined by Aristotle, the golden mean refers to a desirable middle between two extremes in the context of virtue. For example courage can be thought of as a middle ground between recklessness (excessive courage) and cowardice (insufficient courage).

37. The Golden Rule - The principle of treating others as one would wish to be treated oneself.

38. The Platinum Rule - The principle of treating others as they would wish to be treated. For example, you might wish to be treated with brutal honesty and like very spicy food every night, but that doesn’t mean everybody else wants to be treated this way.

39. Categorical Imperative - Coined by Immanuel Kant (famous German philosopher), the categorical imperative says: “Act only according to that maxim whereby you can, at the same time, will that it should become a universal law.”

40. Veil of Ignorance - Coined by John Rawls (an American philosopher), this is a thought experiment that essentially requires you to imagine that you are stripped clean of the life you know. It asks you to assume that you are about to be born somewhere in the world, but you don’t know what race, gender, parents, physical attributes, socio-economic class, etc. you will have. This provides a way of arguing moral issues and deciding what is right or fair in society from an “original position”—behind a barrier of ignorance.

41. Reverse Engineer - Wiki: the processes of extracting knowledge or design information from anything man-made and re-producing it or re-producing anything based on the extracted information.

42. The 4 Cores of Credibility / Speed of Trust Framework - The Speed of Trust is a business book written by Stephen Covey's son, Stephen M. R. Covey. In it, the author makes the important distinction between Character and Competence. The 4 Cores of Credibility are: 1) Integrity 2) Intent 3) Capabilities 4) Results. Cores 1 & 2 belong to Character; cores 3 & 4 belong to Competence. The book also includes a chapter each on 13 Trust Behaviours; overall it's a very comprehensive take on the key elements of trust.

43. Minimum Viable Product - Wiki: In product development, the minimum viable product is a product with just enough features to gather validated learning about the product and its continued development.

44. Minimum Effective Dose - “The smallest dose that will produce a desired outcome.” Coined by Tim Ferriss.

45. The 5 W's (And 1 H) - Who? What? When? Where? Why? How?

46. 2×2 Matrix Diagram - Basically, this is a simple 4-box diagram; the terms assigned to the X and Y axis create the four categories. Johari Window and SWOT are common examples.

47. Decision Matrix - Wiki: a list of values in rows and columns that allows an analyst to systematically identify, analyse, and rate the performance of relationships between sets of values and information.

48. Venn Diagram - A commonly used diagram typically involving two or more overlapping circles. Each circle represents a category and the overlap area creates a shared/combination category.

49. Decision Tree - A tree-like graph with the branches showing the range and results of possible choices for a given decision or course of action.

50. Pros & Cons List - Listing the factors for and against a certain proposal to help weigh the decision.

51. Cost-Benefit Analysis - Related to the Pros & Cons List but more common in business and typically involving financial figures, a cost-benefit analysis adds together all the costs for a given decision and subtracts these from gains to determine if the venture is worthwhile.

52. Supply & Demand - One of the most fundamental concepts in economics, this involves the interaction between supply (the availability of X commodity) and demand (the buying desire for X commodity), which drives the market price of X commodity.

53. Critical Mass / Tipping Point - These terms are often used to refer to the critical amount of people, units, sales, interactions, milestones, etc., required for something to pass a certain threshold level, at which point something big, dramatic, or important happens.

54. The Paradox of Choice - Basically, people get freaked out when you present them with too many options, which is odd because you would think more choice would be better.

55. Trade-Offs - Wiki: a situation that involves losing one quality or aspect of something in return for gaining another quality or aspect.

56. The 80/20 Rule / Pareto Principle - A common pattern observed in a range of business and non-business environments in which about 80% of results are produced by about 20% of activities, which can have important implications for leveraging your time, money, effort, and/or resources.

57. Win-Win - A mutually beneficial arrangement. This can be contrasted with win-lose (I win, you lose), lose-win (you win, I lose), and lose-lose (we both lose). If a business contract doesn’t produce a win-win, it should probably be re-considered.

58. Active Listening - Making attempts in communication to ensure messages are clearly understood, often by use of paraphrasing but also involving emotional warmth, empathy, and patience to ensure the individual’s emotional state and/or position is fully understood.

59. Murphy’s Law - Anything that can go wrong will go wrong. (Sooner or later.)

60. Positive Reinforcement & Negative Reinforcement - Related to concepts such as Extrinsic Motivation, Carrot & Stick, and Behavioural Conditioning, positive reinforcement is the use of rewards to encourage and reinforce a particular behaviour or habit, while negative reinforcement seeks the opposite.

61. Intrinsic Motivation - Behaviour that people engage in because they find it personally or intrinsically rewarding, as contrasted with being compelled by an external incentive or punishment.

62. Hawthorne Effect - Refers to the results of a famous organisational experiment in which workers’ productivity improved, it was suggested, just as a result of the experimenters showing an interest in them.

63. The Forgetting Curve - Refers to the predicable decline in the memory retention of information that can be graphed over time.

64. Ad Hominem Attack - A common logical fallacy where the character of an individual is attacked instead of the substance of his/her argument.

65. False Dichotomy - Presenting only two options or possibilities when more exist.

66. Feedback Loop - Wiki: when outputs of a system are routed back as inputs as part of a chain of cause-and-effect that forms a circuit or loop.

67. Law of Diminishing Returns - Wiki: used to refer to a point at which the level of profits or benefits gained is less than the amount of money or energy invested.

68. Cash Flow Quadrant - Coined by Robert Kiyosaki in the highest selling personal finance book of all time, Rich Dad Poor Dad, the four quadrants are: E - Employee (top left), S - Self-Employed (bottom left), B - Business Owner (top right), I - Investor (bottom right). There is no "best" quadrant since different people have different needs, but the framework is often connected to the concept of passive income / residual income in relation to the Investor quadrant, providing the best chance of obtaining financial freedom.

69. Parkinson’s Law - "Work expands so as to fill the time available for its completion."

70. Maslow’s Hierarchy of Needs - Usually represented as a five-level pyramid, the hierarchy owes its name to Abraham Maslow who postulated five basic human needs or motivations: physiological, safety, love/belonging, self-esteem, and self-actualisation. Once a need is satisfied, humans will tend seek the next level in the hierarchy. Failure to satisfy any of the first four levels (known as "deficiency needs") may create a kind of "psychological crisis."

71. Diffusion of Innovations Curve - A bell-curved shaped theory that describes five main types of consumers: innovators (2.5%), early adopters (13.5%), early majority (34%), late majority (34%), and laggards (16%). The model is often referenced in connection with achieving a point of critical mass for making a product go viral.

72. Gallup Q12 - A series of 12 questions developed by the Gallup—the research company—that were found, by means of a large scale meta-analysis, to be the best predictors of engagement and performance of business teams.

73. Flow - A state of intense psychological absorption in a task.

74. Strengths-Based Thinking - An approach to management and personal development that seeks to identify and develop the strengths in a person or system, rather than spending too much time focusing on the flaws, weaknesses, or negative aspects.

75. Cognitive Dissonance - A state of mental discomfort induced when a person becomes aware of a contradiction in their thoughts, beliefs, or actions. People can be strongly motivated to reduce the feeling of dissonance by a range of mechanisms including denial and rationalisation.

76. IQ vs. EQ - Most people are familiar with IQ: a number derived from taking one or more general mental ability tests, which can have important implications for academic achievement and job performance. EQ or EI is less well known in the general public but has gained a lot of attention in business. EI can be defined as the ability to understand and manage your emotional states, as well as the states of others. Daniel Goleman popularised this term in 1995, putting forward a five factor model of EI: self-awareness, self-regulation, motivation, empathy, and social skills. There are many other models of EI.

77. Big Five Personality Traits - The Big Five theory of personality or five-factor model is the most academically accepted model of basic personality traits, sometimes referred to as the OCEAN model: openness, conscientiousness, extraversion, agreeableness, and neuroticism. These five main factors each exist on a continuum and encompass a number of subfactors.

78. DISC - The DISC model of human behaviour is widespread in business, which can be thought of as a modern update to the four temperaments model of personality developed in ancient Greece. DISC isn't trademarked so there a several model variants; however, the basic theory can be viewed as follows: D: Dominance: outgoing and task focused (tend to be assertive, direct, etc.); I: Influence: outgoing and people focused (tend to be expressive, talkative, etc.) S: Steadiness: reserved and people focused (tend to be amiable, cooperative, etc.); C: Compliance: reserved and task focused (tend to be careful, precise, etc.)

79. Six Thinking Hats - Coined by Edward de Bono and presented as a method of “parallel thinking,” the six hats represent metaphors for adopting a certain type or mode of thinking: White Hat (Hard Facts): Looking at data, information, evidence; Red Hat (Emotions): Looking at feeling, intuition, gut reaction; Black Hat (Scepticism): Looking at potential flaws, faults, dangers, obstacles; Yellow Hat (Optimism): Looking at positive benefits, rewards, value, usefulness; Green Hat (Creativity): Looking at possibilities, suggestions, alternatives; Blue Hat (Process): Looking at the overall process itself.

80. Hanlon’s Razor - "Never attribute to malice that which is adequately explained by stupidity" or "Don't assume bad intentions over neglect and misunderstanding."