The Broken Windows theory argues that crime is the inevitable result of disorder:

• If a window is broken and left unrepaired, people conclude that no one cares and no one is in charge
• This sends a signal that anything goes and the sense of anarchy spreads
• Relatively minor problems like graffiti, public disorder, and panhandling are "small cracks" that invite more serious crimes

"The impetus to engage in a certain kind of behavior does not come from a certain kind of person but from a feature of the environment."

An epidemic can be tipped by tiny changes in context, in the same way that New York's crime epidemic tipped when the police began fixing "broken windows" like graffiti and fare-beating.

Section: 1, Chapter: 4

Author: Malcolm Gladwell

There are two kinds of models that affect our desires differently:

1. People in Celebristan are models separated from us by time, space, money or status. There's little chance of directly competing with them (e.g. celebrities, the ultra-wealthy, the dead). We imitate them openly as their desires don't threaten ours.
2. People in Freshmanistan are models in our immediate social world with whom we can compete directly (e.g. classmates, colleagues, neighbors). Rivalry is common as even minor differences get magnified. We have to secretly wonder at these models as openly imitating them would be embarrassing. In today's world of social media and diminished hierarchies, most of us live in Freshmanistan, vulnerable to the distortions mimetic desire causes there.

Section: 1, Chapter: 2

Author: Luke Burgis

Even when technical issues like p-hacking are addressed, social science faces a "Hard Problem" that stems from the radical uncertainty of the social world:

1. Equifinality: Many models can fit the same data, so drawing firm conclusions is difficult.
2. Reflexivity: Studying social phenomena can alter their dynamics, invalidating models.
3. Causal density: Outcomes arise from complex, ever-shifting interactions, not isolatable variables.
4. Knightian uncertainty: The range of possible futures is often unknowable, rendering precise probability estimates meaningless.

Section: 1, Chapter: 11

Author: Brian Klaas

There seems to be a tipping point in the size of social groups:

• Below 150 members, a group can rely on informal social norms, peer pressure and personal relationships to maintain cohesion
• Above 150, rules, hierarchy, and formal authority are needed to keep order. Things become impersonal and unwieldy.

The dynamics of a group change fundamentally when it exceeds 150 people. This number shows up again and again:

• Hunter-gatherer societies around the world have average village sizes of 148
• Offices tend to max out around 150-200 employees
• The Hutterite religious communities always split when they exceed 150

"At 150, the Hutterites believe, something happens - something indefinable but very real - that somehow changes the nature of community overnight."

By keeping groups under 150, an organization can exploit the bonds of memory and peer pressure to maximize cohesion and trust. Going over that threshold makes an epidemic vulnerable to tipping in the wrong direction.

Section: 1, Chapter: 5

Author: Malcolm Gladwell

According to sociologist Mark Granovetter, weak ties provide value in two key ways:

1. Weak ties expose you to new information and opportunities. They have connections and knowledge that overlap less with what you already know.
2. Interacting with weak ties forces you to communicate from a place of difference. You can't rely on the unspoken assumptions and "restricted speech" you use with your core friend group. You have to engage in "elaborated speech", explaining yourself more fully. This helps you grow.

Section: 1, Chapter: 2

Author: Meg Jay

Researchers have studied how new ideas and innovations spread through a population, known as the diffusion model:

• Innovators are adventurous people who eagerly try new ideas
• Early Adopters are influential, respected, careful choosers
• Early Majority are thoughtful people who accept change more quickly than average
• Late Majority are skeptical people who adopt new ideas after the majority
• Laggards are traditional, conservative people who are last to change

Geoffrey Moore noted a "chasm" between the Early Adopters and Early Majority. Epidemics only tip once you reach the Early Majority. To do that, the idea has to be translated from something specialized and difficult to understand to something accessible to the mainstream. That's the job of Connectors, Mavens, and Persuaders - to bridge the chasm.

Section: 1, Chapter: 2

Author: Malcolm Gladwell

For an idea or product to tip into an epidemic, two things must happen:

1. It must be contagious, spreading from person to person
2. The idea itself must be "sticky" enough to stay in people's minds and compel them to action.

"Stickiness means that a message makes an impact. You can't get it out of your head. It sticks in your memory."

The two work together - a contagious idea will spread quicker if it's also sticky. But both factors must be present for an epidemic to take hold. Making a message contagious isn't enough on its own.

Section: 1, Chapter: 3

Author: Malcolm Gladwell

To create a truthseeking culture, Duke recommends following the Mertonian norms developed by sociologist Robert Merton:

1. Communism (data belongs to the group, not individuals)
2. Universalism (evaluate ideas based on merit, not source)
3. Disinterestedness (be willing to accept outcomes that go against your preferred position)
4. Organized Skepticism (discussion is good, but agree to be bound by logic/evidence)

These principles help overcome biases like confirmation bias, motivated reasoning, and groupthink that can derail group decision making. They create an environment where the best ideas can surface and win out.

Section: 1, Chapter: 5

Author: Annie Duke

Ester Boserup, a Danish economist, proposed the idea that societies that historically used the plough developed more unequal gender norms than those that practiced shifting agriculture. The theory posits that:

• Plough agriculture favors male strength because operating the plough requires upper body strength and grip strength that women on average have less of
• Plough agriculture is less compatible with childcare than shifting agriculture, making it harder for women to combine farm work and family responsibilities
• Plough agriculture is more capital-intensive, favoring men who have more access to land, tools and draft animals than women
• As a result, in societies that relied on animal-drawn ploughs, gender roles diverged and men came to dominate economic and public life while women were relegated to the domestic sphere.

Section: 3, Chapter: 7

Author: Caroline Criado Perez

Think of gossip as the original mass medium. Long before newspapers and TV, it's how people spread information and ideas beyond their immediate circles. And like all media, it operates on a "pay to play" model. The most eager listeners gain access to the juiciest morsels. The best talkers attract the most attentive audiences. Gossip's grapevine turns private affairs into public knowledge and public events into private passions. As we whisper, eavesdrop, and pass along tales, we collectively decide what deserves discussion and judgment and what merits discretion and tact. Bit by bit, the currency of gossip establishes our social and moral economies.

Section: 1, Chapter: 16

Author: Kate Murphy

Adlerian psychology views feelings of inferiority as subjective evaluations rather than objective facts. People feel inferior based on their own interpretations of themselves in comparison to others or to their ideal selves.

The philosopher notes that his own feeling of inferiority about his height was a subjective judgment, not an actual lack of worth: "My height of 61 inches in itself was not inferior at all. It was rather that the value I attached to that height was the issue."

Section: 2, Chapter: 13

Author: Ichiro Kishimi and Fumitake Koga

If all problems are interpersonal problems, as Adler asserts, then what is the ideal state of interpersonal relationships? The philosopher states Adler's answer is "community feeling."

Community feeling means sensing one's "belongingness" and contribution to the community. It stems from having concern for others beyond oneself, and from cooperating on an equal basis. The philosopher elaborates:

Section: 4, Chapter: 34

Author: Ichiro Kishimi and Fumitake Koga

The Big Fish-Little Pond Effect refers to the fact that we form our self-concept not in absolute terms, but relative to our immediate peer group. In school, this means our self-image is shaped by how we rank compared to our classmates, not how we rank in ability nationally.

So a student with above-average intelligence can end up with a poor academic self-concept if they are placed in a gifted program where they are below-average compared to their peers. Meanwhile, a student of equal ability in a regular program will have a much more positive self-image.

This has major implications for academic effort, aspirations and career choice. Students are more likely to persevere in fields where their relative standing is high. Being a Big Fish in a Little Pond is often preferable to being a Little Fish in a Big Pond.

Section: 1, Chapter: 3

Author: Malcolm Gladwell

The Law of the Few relies on three key types of people who are critical to social epidemics:

1. Connectors are people with a special gift for bringing the world together. They have extraordinarily large social networks and are great at making friends and acquaintances. Examples include Paul Revere and the popular girl in high school who knows everyone.
2. Mavens are information specialists. They accumulate knowledge and are eager to share it with others. They start word-of-mouth epidemics due to their knowledge, social skills, and ability to communicate. Examples include a friend who knows all about the latest gadgets or restaurants.
3. Persuaders are charismatic people with powerful negotiation skills. They exert "soft" influence rather than direct persuasion. Examples include successful salespeople and advertisers.

Any social epidemic tips because of the involvement of Connectors, Mavens, and Persuaders. They are the ones who make things happen.

Section: 1, Chapter: 2

Author: Malcolm Gladwell

According to anthropologist Robin Dunbar, the human brain can only handle about 150 close relationships at a time. As a social group grows, the number of links between members increases exponentially, not linearly. Keeping track of those relationships consumes more and more mental effort.

At some point the brain reaches its limit. Dunbar found a strong correlation between primate brain size and average social group size. For humans, that cognitive boundary seems to be 150.

"The figure of 150 seems to represent the maximum number of individuals with whom we can have a genuinely social relationship, the kind of relationship that goes with knowing who they are and how they relate to us."

By staying under Dunbar's number, an organization can tap into the brain's natural social wiring, and prevent social cohesion from breaking down.

Section: 1, Chapter: 5

Author: Malcolm Gladwell