Simple Rules

How do you make good decisions in a world that’s becoming more complex every day? Whether you’re managing a business, leading a team, or just trying to get healthier, life often feels overwhelming because the moving parts never stop multiplying. In Simple Rules: How to Thrive in a Complex World, MIT professor Donald Sull and Stanford University’s Kathleen M. Eisenhardt argue that success in a complex environment doesn’t come from mastering complexity—it comes from simplifying wisely. They show that a handful of well-chosen, flexible rules can help you make better decisions, seize fleeting opportunities, and work more effectively with others.

Sull and Eisenhardt’s central insight is deceptively counterintuitive: as systems become more complicated, our best response isn’t to add more policies, more data, or more procedures. It’s to simplify. Complex problems rarely yield to complex solutions; they thrive on them. The authors show that simple rules—the kind that guide fighter pilots, surgeons, honeybees, investors, football coaches, and entrepreneurs—work better than any grand plan because they impose just enough structure without stifling flexibility. They’re not rigid formulas but living heuristics that evolve as conditions change.

Why Simplicity Wins in a Complex World

The book opens with a gripping scene: army medics in Iraq triage dozens of wounded soldiers after a bombing. They have seconds to decide who to treat first, who can wait, and who cannot be saved. They use simple color-coded rules—green tags for the lightly wounded, red for the critical, black for those beyond help. These rules are brutally efficient because they mirror real life: limited time, incomplete information, and the need for quick, collective action. In both war and business, the medics’ triage system captures the essence of what simple rules accomplish—they focus attention on what matters most and prevent paralysis amid complexity.

Sull and Eisenhardt argue that modern life creates its own kind of battlefield. From managing global supply chains to navigating digital overload, people are bombarded with choices and data. Our instinct is to respond with more—more analysis, more technology, more processes. But counterintuitively, less really is more effective. Like Michael Pollan’s now-famous dietary mantra—“Eat food. Not too much. Mostly plants.”—simple rules distill vast knowledge into memorable, actionable principles. They’re easy to retain, flexible in context, and potent in impact.

What Simple Rules Are—and Are Not

Simple rules aren’t vague slogans or micromanaged procedures. They fall between platitude and policy—specific enough to act on, but broad enough to apply flexibly. The authors define them by four traits:

• They consist of a small number—usually three to five—that target a key decision or activity.
• They’re tailored to the person, team, or organization using them.
• They address a specific bottleneck—a decision or activity that strongly influences success.
• They balance structure with flexibility, offering guidance without rigidity.

Each simple rule clarifies what should be done while leaving space for judgment. That’s what makes them “simple, but not simplistic.” And, crucially, they differ from standardized checklists—like airline safety procedures or surgical protocols—that operate in stable, predictable settings. Simple rules thrive in dynamic, fast-moving environments where you need to adapt.

Six Types of Rules

The book identifies six categories of simple rules that guide decisions and action:

• Boundary rules define what’s in or out—for example, judges or burglars deciding whether a case or a house is worth the risk.
• Prioritizing rules rank choices when resources are limited, such as determining which hospital patients or sales opportunities deserve attention first.
• Stopping rules dictate when to quit—selling a stock, ending a project, or turning around on Everest.
• How-to rules guide execution, like NASA’s launch checklist or a novelist’s creative constraints.
• Coordination rules govern group interactions—how bees swarm or comedians improvise without chaos.
• Timing rules set when to act, as in Pixar’s rule to release one movie every year or investors’ “buy when there’s blood on the streets.”

These categories allow anyone—from entrepreneurs to parents—to craft personalized, context-sensitive rules that drive consistent, effective action while staying adaptable.

The Power—and Pattern—of Simplicity

Throughout history, from Jesuit missionaries to modern tech companies, simple rules have powered extraordinary achievements. They work because they mirror how our brains actually function under stress and uncertainty. Nobel laureate Daniel Kahneman (in Thinking, Fast and Slow) distinguishes between the brain’s fast, intuitive thinking and its slow, deliberate reasoning. Simple rules leverage the fast system—they’re cognitively easy, quick to recall, and action-ready.

Over the book’s nine chapters, Sull and Eisenhardt combine powerful stories—Stanford football’s injury-proof strategy, poker players’ emotional discipline, Airbnb’s learning journey—with field research from startups and executives. They show that every effective simple rule begins messy and evolves through experience. The trick is to codify what works, test it, and prune what doesn’t. Simplicity, here, isn’t naive—it’s disciplined minimalism. It’s knowing precisely which few things matter most and letting everything else go.

Ultimately, the authors’ message is bold but liberating: when the world becomes chaotic, resist the urge to control it with complexity. Instead, simplify your playbook—and you’ll thrive where others freeze.

Why do simple rules outperform complicated strategies? Sull and Eisenhardt begin their argument with Michael Pollan’s three dietary rules—“Eat food. Not too much. Mostly plants.” These guidelines are simple yet supported by science and experience. Likewise, effective simple rules distill the chaos of any system into memorable guidance that nudges everyday choices toward success.

Flexibility Beats Rigidity

The authors show that rules succeed because they strike the right balance between flexibility and consistency. Detailed rulebooks (like McDonald’s operations manual) ensure precision and uniformity, but they stifle spontaneity. The Jesuit order thrived in the sixteenth century precisely because its founding “Formula,” unlike the rigid Benedictine code, offered only a handful of rules. Jesuits could adapt their missions—from Brazil to Japan—while maintaining a coherent purpose. Their main rule, “help souls,” was clear but open-ended. This flexibility helped them grow from ten men to a thousand in two decades.

Better Decisions, Less Noise

Simple rules also outperform complex models when information is limited or cause-and-effect is uncertain. Citing psychologist Gerd Gigerenzer’s research, the authors reveal how heuristics (mental shortcuts) often outperform data-heavy algorithms. Gigerenzer found that a simple rule—“Take the midpoint of the two farthest crime scenes”—helped police locate serial offenders more accurately than expensive statistical models. Likewise, investors, surgeons, and entrepreneurs regularly make better choices using a few guiding criteria than by overanalyzing data.

More data doesn’t always mean better decisions. Complex models can overfit the past and fail to predict the future. Simple rules cut through noise, focusing attention on the few factors that matter most.

Rules That Foster Collective Action

Equally striking is how simplicity enables group coordination. Honeybees, for example, use three basic rules—dance longer for better sites, follow the first dancer you see, and head-butt those promoting other sites—to reach consensus on a new nest location. No bee knows the full picture, yet the colony makes fast, optimal group decisions. Sull and Eisenhardt note that human organizations work similarly: good simple rules help distributed groups act cohesively without micromanagement. Zipcar, for instance, aligned thousands of strangers to share cars smoothly with just six rules (like “No smoking” and “Return on time”).

In short, simple rules work by reducing cognitive load, clarifying priorities, and enabling coordinated action. They create a framework for adaptive behavior amid complexity—arguably the most critical skill of our age.

After analyzing organizations from DARPA to McDonald’s, the authors identify six practical categories of simple rules, each serving a distinct decision-making challenge. Together, they offer a universal grammar for navigating complexity.

Decision Rules: Boundary, Prioritizing, and Stopping

Boundary rules define what’s acceptable or off-limits. For example, judges deciding bail rely on a few immediate cues—if the prosecution objects, bail is denied. Likewise, burglars in a study steered clear of homes with cars outside—a surprisingly accurate proxy for someone being home. Boundary rules are quick filters that prevent wasted energy.

Prioritizing rules rank what matters most when resources are scarce. A vivid example comes from Brazil’s América Latina Logística (ALL) railroad. With limited money, CEO Alex Behring used four rules to choose investments: remove bottlenecks, get quick results, minimize up-front costs, and reuse resources. Within three years, revenues jumped 50%.

Stopping rules determine when to quit. Gerald Loeb’s famous investing heuristic—“Sell if a stock drops 10%”—saved investors from ruin during market crashes. Tragically, climber Scott Fischer’s expedition on Everest in 1996 proved the opposite: ignoring their two-o’clock turnaround rule led to disaster. Stopping rules combat escalation of commitment and ensure survival.

Process Rules: How-To, Coordination, and Timing

How-to rules guide execution. BBC’s pioneering sports director Seymour Joly de Lotbiniere taught commentators six timeless steps for live coverage—set the scene, describe the action, give the score, and so on. These became the DNA of modern sportscasting. Similarly, firefighter Wag Dodge’s “escape fire” rule at Mann Gulch was a lifesaver when others panicked.

Coordination rules orchestrate groups. Starlings flock in perfect harmony by following three: avoid collisions, stay close, and align direction. Humans mirror this in improv comedy, where performers use cues like “Yes, and …” to keep a scene flowing. Simple coordination rules sustain order without central control.

Timing rules set rhythms and deadlines. Pixar’s rule to release one movie per year established creative consistency. Stanford Startup Chile’s two-month review cycles and Demo Day cadence gave entrepreneurs accountability. Timing rules inject momentum and regulate pacing in chaotic systems.

Collectively, these six rule types create a toolkit that works anywhere—from boardrooms to kitchens. They are not rigid templates but adaptable mental structures that simplify decision and action.

When companies lose focus, they don’t need thicker binders—they need clarity. Eisenhardt and Sull’s case studies of eToro and dozens of firms in the Young Presidents’ Organization (YPO) reveal how high-performing leaders replace bureaucratic strategy with tailored rules that everyone understands.

Three Steps to Strategic Simplicity

The process begins with three deceptively simple steps: (1) identify what moves the needles—what truly drives revenue up or costs down; (2) pinpoint the bottleneck—the key decision or activity that constrains growth; and (3) craft a handful of simple rules to guide that activity.

In the case of eToro, a social trading platform, the founders realized growth depended on cultivating “Popular Investors.” Their bottleneck was selecting and supporting those top traders. Once they created clear rules—reward consistent performers, require transparent profiles, limit bonuses—the program exploded, tripling engagement.

Alignment and Learning in Action

Another entrepreneur, Janis Oslejs of Primekss, used simple rules to transform his concrete business. By focusing only on international licensing partners with technical capacity and avoiding markets where they already operated, Primekss quadrupled exports in a year. Similarly, restaurant owner Sanjiv Suri in Prague used rules to design cafeteria menus—three bestsellers daily, 90% local ingredients, plan weekly menus by Wednesday noon. Profits doubled.

Across all cases, simple rules democratized strategy. When employees help write them, they internalize decision logic and execute autonomously. These weren’t slogans like “delight the customer” but actionable, measurable guides. The lesson: a good rule replaces ten memos.

Simple rules evolve through experience. Shannon Turley, Stanford’s award-winning strength coach, illustrates this beautifully. At Virginia Tech, he began with the conventional “lift heavier to get stronger.” Over years—through football, baseball, volleyball, and wrestling—he refined his approach to focus on injury prevention, functionality, and athlete autonomy. The result: injuries dropped 87%, and Stanford became a powerhouse.

The Pattern of Improvement

Eisenhardt and UNC’s Chris Bingham found that simple rules follow a predictable improvement trajectory: (1) they begin rough and reactive; (2) evolve toward strategic relevance; (3) grow in number, then shrink to a stable set through “simplification cycling.” People also learn rule types sequentially—starting with boundaries, then moving to timing, prioritizing, and coordination rules as expertise deepens.

Entrepreneurs expanding abroad learned the same. Finnish startups first entered familiar markets like Sweden, but refined their rules to prioritize market size instead of proximity: “Enter large European markets.” Through group reflection meetings and shared learning, they achieved faster growth.

Learning through Reflection and Variation

What accelerates improvement? Two processes: reflection and related experience. Like Turley’s training journal, or poker player Raghu Shukla’s habit of reviewing every session, reflection turns activity into learning. Raghu went from math whiz to professional-caliber player by iterating between poker types (home games, online, casinos, Vegas) and recording insights. Likewise, diversity of experiences—Airbnb founders alternating between New York fieldwork, Y Combinator dinners, and product experiments—spurs breakthroughs.

When multiple learning paths combine—reflection, related practice, feedback—they compound. The more varied but connected the experience, the faster rules improve. This is expertise in motion.

Sometimes, improving existing rules isn’t enough—you must break and remake them. When California’s drought upended everyday life, homeowners like Emily abandoned temperate English-garden ideals for Mediterranean-savvy rules: plant in fall, no summer watering, emphasize foliage texture over endless blooms. Rapid, complete transition beats gradual adaptation. The same logic powers business renewal.

From Moneyball to Arbitrage

The Oakland A’s famously used “moneyball” rules—hire undervalued players with high on-base percentages—to outsmart richer teams. When everyone copied, GM Billy Beane and Farhan Zaidi rewrote the playbook. Their new vision treated baseball as market arbitrage: recruit players with extreme performance splits, orchestrate platoons, and favor fly-ball hitters. They created value where the market hadn’t looked. Innovation often begins by breaking yesterday’s winning rules.

From Sitcom to Streaming Revolution

Similarly, Netflix’s House of Cards disrupted television by redefining three bottlenecks—directing, programming, and talent. Instead of pilot testing, it committed two full seasons upfront, trusting its data analytics to guide decisions. It hired film director David Fincher and A-list actor Kevin Spacey to produce cinematic TV, then released all episodes at once. By flipping industry norms, Netflix established binge culture and proved that rule-breaking can scale simplicity—if grounded in clear vision and data-driven confidence.

When disruption strikes, simplicity still wins—but the right simple rules must be newly forged to fit the new game.

In their conclusion, Sull and Eisenhardt warn that complexity isn’t destiny—it’s a design choice. We often manufacture it through overregulation and fear. The antidote is personal and institutional courage to simplify. Federal Reserve Chair Janet Yellen, for instance, managed U.S. monetary policy using one clear timing rule—keep rates low until inflation and employment hit targets. Her “mind-the-gap” rule simplified decisions across a multi-trillion-dollar system.

Even central banking, the archetype of complexity, thrives on simplification. Just as ancient Roman law applied prioritizing rules to sift legal opinions, today’s regulators can test which policies truly create justice or stability. Too often, societies pile on rules out of mistrust. Netflix’s internal policy—“Act in Netflix’s best interests”—replaces 100-page HR manuals. Trust and clarity beat surveillance.

Simple rules don’t restrict—they liberate. They enable creativity, accountability, and real human judgment to flourish amid uncertainty.

The authors end where they began: in a chaotic world, overcomplication promises control but delivers paralysis. Freedom lies not in more rules, but in the right few. Whether you’re designing policy, strategy, or life itself, simplicity is your greatest strength.