Fighting Complexity With Simplicity

Exploring simple rules for how to do everything

The Sixty-Seventh Combat Support Hospital, lo­cated 250 miles northwest of Baghdad, was not like most hospitals. For starters, the doctors carried guns. As offi­cers in the U.S. Army, the physicians were required to wear side­-arms, which were deposited in a lockbox before every shift. The hospital often treated Iraqi insurgents, who were known to spit in attending physicians’ faces as they received treatment. If they (or a disoriented U.S. soldier) got their hands on a weapon, a firefight could break out in the operating room.

Built on the bombed-out remains of a farmer’s field near the Mosul International Airport, the hospital, a cluster of buildings, trailers, and large green tents, was surrounded by concrete bun­kers and blast walls to protect the staff and patients from mortar fire. The medical staff spent days at a time treating routine condi­tions like indigestion and dehydration (in summer, temperatures in the region could reach 120° Fahrenheit, hot enough to stick the contact lenses to the eyes of soldiers as they walked from one building to another). Lulls could be interrupted at any moment by an onslaught of wounded soldiers and civilians.

At noon on December 21, 2004, at nearby Forward Operating Base Marez, U.S. troops, Iraqi soldiers, and military contractors crowded into the mess tent for lunch. Sergeant Edward Montoya Jr., an Army medic who normally avoided sweets, was feeling homesick at the prospect of Christmas in Iraq and decided to console himself with a piece of cheesecake. As he headed for the dessert table, his buddies ribbed him about putting on weight.

At the same moment, a man wearing an Iraqi security services uniform entered the mess tent, approached a cluster of U.S. sol­diers waiting in line for lunch, and detonated an explosive vest concealed under his uniform. Montoya was returning to his seat when he saw a flash out of the corner of his eye, followed by what he remembers as “the largest boom in the history of booms.”

Montoya dove under a table and, as the mess tent filled with smoke,
pulled several disoriented soldiers to cover.

After assessing the injuries of a soldier lying next to him, Mon­toya got to his feet and moved quickly through the tent to evalu­ate and treat the wounded. One soldier had blood spurting from a femoral artery, and Montoya used his belt to fashion a makeshift tourniquet, securing it around the soldier’s leg and applying table napkins to stanch the bleeding. As Montoya moved from soldier to soldier, he checked vital signs — pulse, responsiveness, blood pressure — to gauge the severity of the injuries, using a handful of simple rules to prioritize the injured for care.

The most urgent cases were sent to the Sixty-Seventh Combat Support Hospital. In the span of a few hours, the hospital ad­mitted ninety-one casualties, an influx that overwhelmed its lim­ited resources. Patients pressed up against the hallways to make room for passing medical staff. The less seriously injured had to wait in the parking lot until space freed up indoors. The doctors conducted some of the simpler surgical procedures outside the operating room, and judiciously allocated their dwindling stock of medical supplies. Like Montoya, the hospital staff used a set of rules to sort patients who required immediate care from those who could afford to wait.

Treating traumatic injuries is difficult under the best of cir­cumstances, and combat is about as far from ideal as you can get. The injuries are often severe, the physical conditions bleak; medical staff work under the constant threat of assault, and criti­cal supplies are limited. In 2004 the Army had about fifty sur­geons in Iraq to serve 140,000 troops as well as injured civilians and military contractors. Despite the challenges of medical care in wartime, by the beginning of the twenty-first century com­bat mortality rates had fallen to surprisingly low levels. Only one out of every ten American soldiers injured in Afghanistan and Iraq died of their wounds, well under half the mortality rate of soldiers wounded in Vietnam, and a world away from the 42 percent mortality rate of soldiers wounded in the Revolutionary War. This impressive survival rate is the culmination of continu­ous improvements in frontline medical care over the past two hundred years. In the grim arms race between medical improve­ments and ever deadlier weaponry, the doctors are pulling ahead.

Advances in drugs, surgical techniques, and diagnostic equip­ment are the obvious sources of progress in survival rates. Also important, but less familiar to most people, are improvements in how armies allocate scarce resources in the face of mass casual­ties. Medical professionals are trained to do whatever they can to help the patient lying in front of them, but frontline medics, medevac pilots, and military doctors must make hard choices about whom to treat first. In the wake of an attack or battle, med­ics and admitting physicians are forced to make life-and-death decisions about complex injuries, with limited information, un­der tremendous time pressure, and often under fire.

Throughout most of history, the allocation of medical re-sources was haphazard. The poet Walt Whitman, who served as a nurse during the U.S. Civil War, observed that the injured were cared for on a first come, first served basis, regardless of the se­verity of their injuries. The wounded sat in line, waiting patiently for their turn to be seen by a doctor or nurse. After the First Battle of Bull Run, the injured who were able had to walk the thirty-mile distance from the battlefield to hospitals in Washington for treatment, a system that failed those most in need of care, the soldiers lying on the battlefield.

In the Second World War, the U.S. surgeon general introduced a formal process for prioritizing care in order to reduce deaths. The system is known as triage, after the French word for sort­ing commodities, such as wheat or coffee beans, into categories based on their quality. Given the complexity of the injuries they encounter, you might think medics use complicated algorithms to classify the wounded. They don’t. Instead they rely on a hand­ful of simple rules, like those employed by Montoya and the Sixty-Seventh medical staff, to quickly sort injured patients into three or four categories, prioritizing them for treatment. When performing frontline triage, medics will typically spend less than a minute with each patient. Simple guidelines, such as whether the patient can follow instructions, has a pulse rate below 120, or a respiratory rate between ten and thirty breaths per minute, allow medics to quickly evaluate the wounded. The injured are then assigned a color-coded tag that categorizes them according to the severity of their injuries.

Those with stable vital signs are tagged with the color green — treatment can safely be delayed for these “walking wounded.” At the other extreme, patients who are unlikely to survive even with heroic intervention are tagged with black and provided palliative care. The remaining patients are first in line for care, with the more badly injured given a red priority tag and the others a yel­low tag denoting “urgent.” Sorting the patients using these simple rules ensures that scarce medical resources are brought to bear where they can do the most good — on those patients who have a shot at survival, but only if they receive immediate attention. The rules of triage are widely used to allocate medical resources — such as intensive-care-unit beds or vaccines during a flu pan­demic — in the face of mass casualties. After the Boston Mara­thon bombings, for example, a first-aid center set up at the finish line was transformed from treating sprained ankles and dehydra­tion to performing rapid-fire triage, prioritizing the wounded for care and directing the most severely injured to nearby hospitals.

The rules of triage are an excellent example of what we call simple rules, the rules of thumb that people and organizations use to make decisions and take action quickly and efficiently.

The Power of Simple Rules

Simple rules are shortcut strategies that save time and effort by focusing our attention and simplifying the way we process infor­mation. The rules aren’t universal — they’re tailored to the par­ticular situation and the person using them. We all use simple rules every day, whether we’re aware of them or not. You may have consciously decided never to check your email before you have a cup of coffee in the morning, for example, or never to go on a second date with someone who only talks about themselves. But chances are you also rely on simple rules to decide what to wear, where to invest, or how to stay fit, without even realizing you’re following them. Simple rules allow people to act without having to stop and rethink every decision. That is why frontline medics use them to make fast and reasonably accurate decisions about who gets medical care.

Simple rules have proven highly effective in a wide range of activities beyond frontline triage. They help guide critical policy decisions, including how the Federal Reserve Board fixes interest rates, how the state of California protects its marine wildlife, and how the president of the United States approves targets for drone strikes.

Tina Fey used simple rules to produce the hit comedy 30 Rock, Elmore Leonard used them to write a series of bestsellers over sixty years, and the White Stripes used them to record one of the most acclaimed rock albums of the past twenty years in only ten days. Simple rules help judges decide whether to grant bail, and police officers to determine if a suicide note is authen­tic. In nature, starlings employ simple rules to fly in unison, and crickets use them to decide when to stop searching and settle on a mate. Sometimes simple rules can mean the difference between life and death. Ignoring them contributed to one of the most deadly days for climbers in Mount Everest’s history, and one of the most lethal forest fires in U.S. history.

Simple rules work, it turns out, because they do three things very well. First, they confer the flexibility to pursue new oppor­tunities while maintaining some consistency. Second, they can produce better decisions. When information is limited and time is short, simple rules make it fast and easy for people, organiza­tions, and governments to make sound choices. They can even outperform complicated decision-making approaches in some situations. Finally, simple rules allow the members of a commu­nity to synchronize their activities with one another on the fly. As a result, communities can do things that would be impossible for their individual members to achieve on their own. Bee colonies, for example, use simple rules to find a new nest, and members of Zipcar relied on simple rules to share cars across thousands of users. In the next chapter, we’ll expand on why simple rules are so powerful.

At first glance, the rules of triage have nothing in common with, for example, the rules geese follow to flock in tight forma­tions. But a deep unity lies beneath the variety. Whether they are used by rock stars or crickets, effective simple rules share four common traits. First, they are limited to a handful. Capping the number of rules makes them easy to remember and maintains a focus on what matters most. Second, simple rules are tailored to the person or organization using them. College athletes and mid­dle-aged dieters may both rely on simple rules to decide what to eat, but their rules will be very different. Third, simple rules apply to a well-defined activity or decision, such as prioritizing injured soldiers for medical care. Rules that cover multiple activities or choices end up as vague platitudes, such as “Do your best” and “Focus on customers.” Finally, simple rules provide clear guid­ance while conferring the latitude to exercise discretion. Central bankers, for example, use simple rules not as a mechanistic tool to dictate interest rates, but as guidelines within which they exer­cise judgment. Rules come in all shapes and sizes, ranging from implicit heuristics we use to make snap decisions to voluminous regulations affecting small businesses. Simple rules, as we use the term, refers to a handful of guidelines tailored to the user and task at hand, which balance concrete guidance with the freedom to exercise judgment. The dozens of diverse examples of simple rules provided throughout this book all share these four traits.

The Discovery of Complexity

Simple rules provide a powerful weapon against the complexity that threatens to overwhelm individuals, organizations, and society as a whole. Complexity arises whenever a system — technical, social, or natural — has multiple interdependent parts. The hu­man body, bees in a hive, a soccer team, and international bank­ing are all examples of complex systems — they consist of many components and interdependencies that can change unpredict­ably and frequently.

To visualize complexity on a small scale, you need look no farther than your living room. A home entertainment system consists of multiple components — screen, DVD player, game console, cable box, and speakers — that need to work together. Integrating more parts into the system opens up new possibili­ties, such as binge-watching House of Cards on Netflix, but also increases the number of things that can go wrong and the number of remotes (three per household on average) required to manage the system. The defining issues of our time — climate change, the global financial crisis, international terrorism, the shift toward emerging markets — all arise out of the churning interactions of complex systems.

Complexity itself is not new — the Roman Empire was one of the most complex political systems in history — but our recogni­tion of complexity has vastly increased in the past six decades. A search for the word complexity in five million books published since 1800 shows that the term was initially rare, rose gradually for 150 years, and then exploded just after the Second World War. The upsurge in interest coincided with the publication, in Octo­ber 1948, of an eight-page article entitled “Science and Complex­ity,” written by an unassuming mathematician named Warren Weaver.

Warren Weaver is not a household name, but he may be the most influential scientist you’ve never heard of, actively shaping three of the most important scientific revolutions of the last cen­tury — life sciences, information technology, and agriculture.

In 1932 Weaver joined the Rockefeller Foundation to lead the di­vision charged with supporting scientific research. Funding was scarce during the Great Depression, and the Rockefeller Founda­tion, with an endowment nearly twice the size of Harvard’s at the time, was one of the most important patrons of scientific research in the world. Over his three decades at the Rockefeller Founda­tion, Weaver acted as a banker, talent scout, and kingmaker to support the nascent field of molecular biology, a term he him­self coined. Weaver had an uncanny knack for picking future all-stars. Eighteen scientists won Nobel Prizes for research related to molecular biology in the middle of the century, and Weaver had funded all but three of them.

Weaver recognized the potential of computers long before most people even knew they existed. He wrote a seminal paper that laid out how computers could translate text from one lan­guage to another, sixty years before the creation of Google Trans­late and Babylon. While at the Rockefeller Foundation, Weaver also handpicked and financed a team that spent two decades de­veloping high-yield varieties of wheat that were impervious to disease. Their work helped Mexico feed itself within a genera­tion. When India and Pakistan faced widespread famine in the early 1960s, they adopted the practices pioneered by the Rock­efeller team, and doubled their wheat production in five years, saving hundreds of millions of people from starvation.

As if spurring on three scientific revolutions were not enough, Weaver also pioneered the study of complexity. In his 1948 ar­ticle, Weaver described science as progressing through successive eras, defined by the three types of problems — simple, uncertain, and complex — that they solved. Simple problems address a few variables that can be reduced to a deterministic formula. Isaac Newton’s laws of motion (force = mass x acceleration, for exam­ple) were powerful tools to solve simple problems, such as how a satellite orbits the Earth or what happens when two billiard balls collide. Simple problems occupied scientists for most of the seventeenth to nineteenth centuries, and their solutions yielded life-changing inventions ranging from the telephone to the diesel engine. By the late nineteenth century, scientists shifted their at­tention to problems of uncertainty, such as the motion of gas par­ticles in a jar, which consisted of large numbers of objects. While scientists could not track the movement of every molecule, they could use probability theory and statistical analysis to predict how large numbers of particles behave in aggregate, paving the way for advances in thermodynamics, genetics, and information theory.

Scientists can predict the path of two billiard balls with preci­sion, and the average behavior of two million gas particles. But what about the messy middle ground, where twenty or thirty components interact with one another in unexpected ways? Many of the most critical scientific and social challenges of today — the aging of cells, or hunger in emerging markets — result from mul­tiple variables that interact in numerous and often unpredictable ways. Complexity covers the untidy yet vibrant realm where so much of life unfolds. What makes a primrose open when it does? How do market forces influence the price of gold? How will an expectant mother’s diet affect her child? When will a concussion permanently damage the brain?

The world was complex in 1948 when Weaver wrote his influ­ential article, and since then it has become significantly more so. Since the fall of the Berlin Wall, the fates of the world’s economies have become more interwoven, with the number of international trade agreements increasing sixfold since 1990. Over the same time, global air traffic has increased nearly threefold, facilitat­ing the mix of people and commerce around the world. Capital has followed trade, and in the past few decades the correlation between countries’ stock markets has more than doubled, while banks’ exposure to debt beyond their home markets has nearly tripled. And of course the Internet has revolutionized intercon­nectedness in a way comparable only to the invention of the printing press or perhaps even the development of writing itself. It is easy to forget that Google is still a teenager, and Facebook is in elementary school.

Weaver argued that simple and uncertain problems have largely been solved, and that the greatest challenges of the future would be problems of complexity.
He was right.

At the personal level, many of us struggle to manage complexity every day. We have to call a teenager to navigate the three remote controls re­quired to turn on ESPN, an accountant to fill out our tax forms, and the IT help desk for guidance every time Microsoft intro­duces a new version of its software.

On a macro level, the great issues of our day, almost without exception, arise from the unpredictable interactions of many moving parts. High default rates on subprime mortgages (which totaled less than 3 percent of U.S. financial assets) spread like a contagion through the global financial system in the late 2000s, infecting previously healthy banks around the world and trigger­ing the most severe downturn since the Great Depression. Af­fordable and high-quality health care for an aging population de­mands cooperation among patients, doctors, hospitals, insurance providers, and governments, all of whom have different agendas. Across the Atlantic, Europeans struggle to retain their tradi­tional lifestyles and national sovereignty even as their destinies are inextricably linked with others in Europe, the Middle East, and the rest of the world. And of course there is climate change, the mother of all challenges, arising from the interactions among technology, population growth, and the global ecosystem, and af­fecting everyone.

Simple Rules for a Complex World

People often attempt to address complex problems with complex solutions. For example, governments tend to manage complexity by trying to anticipate every possible scenario that might arise, and then promulgate regulations to cover every case.

Consider how central bankers responded to increased com­plexity in the global banking system. In 1988 bankers from around the world met in Basel, Switzerland, to agree on interna­tional banking regulations, and published a 30-page agreement (known as Basel I). Sixteen years later, the Basel II accord was an order of magnitude larger, at 347 pages, and Basel III was twice as long as its predecessor. When it comes to the sheer volume of regulations generated, the U.S. Congress makes the central bank­ers look like amateurs. The Glass-Steagall Act, a law passed dur­ing the Great Depression, which guided U.S. banking regulation for seven decades, totaled 37 pages. Its successor, Dodd-Frank, is expected to weigh in at over 30,000 pages when all supporting legislation is complete.

Meeting complexity with complexity can create more confu­sion than it resolves. The policies governing U.S. income taxes totaled 3.8 million words as of 2010. Imagine a book that is seven times as long as War and Peace, but without any characters, plot points, or insight into the human condition. That book is the U.S. tax code. Such an exhaustive tome should leave nothing to chance. And yet, when forty-five tax professionals were given identical data to calculate one fictional family’s tax bill, they came up with forty-five different estimates of the couple’s tax liability, ranging from $36,322 to $94,438. The tax code is so confusing, even IRS experts give the wrong advice one time out of three. To navigate this labyrinth, U.S. citizens employ 1.2 million tax preparers, more than all the police and firefighters in the country combined.

Applying complicated solutions to complex problems is an understandable approach, but flawed. The parts of a complex system can interact with one another in many different ways, which quickly overwhelms our ability to envision all possible outcomes. To illustrate how quickly complexity escalates out of control, consider an apparently simple question: How many ways can you combine six Lego blocks? For one block, the answer is trivial: 1. With some work, most people can calculate that two blocks combine in 24 ways, but by three blocks the calculation becomes tricky (the correct answer is 1,560). When you get to six blocks, the number of possible combinations is daunting. For decades, the commonly accepted answer for six blocks was 103 million combinations, until two mathematicians revisited the problem with massive computer power and discovered 915 mil­lion combinations. If professional mathematicians, among the smartest people on the planet, struggle to work out the possible combinations of six Lego blocks, what are the odds that members of the U.S. Congress can envision every contingency when draft­ing legislation to cover banking or taxation?

Complicated solutions can overwhelm people, thereby in­creasing the odds that they will stop following the rules. A study of personal income tax compliance in forty-five countries found that the complexity of the tax code was the single best predictor of whether citizens would dodge or pay their taxes. The complex­ity of the regulations mattered more than the highest marginal tax rate, average levels of education or income, how fair the tax system was perceived to be, and the level of government scrutiny of tax returns. Or take retirement savings. According to the mu-tual-fund giant Fidelity Investments, fewer than half of all Amer­icans are on track to cover their expenses when they retire. When employers offered two options for investment in their 401(k) re­tirement plans at work, three-quarters of workers signed up. As the number of options on offer proliferated, however, participa­tion dropped (to 61 percent for plans with many choices) — even when employers matched their employees’ contributions. Over­whelmed by complexity, people walked away from free money.

Books on complexity tend to fall into two camps. Thousands of science books explain theories of chaos, complexity, and adap­tive systems, and complexity is currently a hot topic in scientific research. At present, there are at least a dozen scientific journals devoted to the study of complex systems, and more than thirty research centers, including the well-known Santa Fe Institute, and the Observatory of Economic Complexity housed at MIT’s Media Lab. Science books on complexity are often fascinating, but rarely provide much practical guidance on how to manage it. A second camp of books veers to the opposite extreme, offering homespun advice on how to simplify your life by decluttering your closets, for example, or limiting the number of blogs you read. Self-help advice, while well-intentioned, lacks grounding in research and offers little insight on how to manage complexity in larger systems.

Simple Rules offers a fresh perspective on a fundamental ques­tion: How can people manage the complexity inherent in the modern world? Our answer, grounded in research and real-world results, is that simple rules tame complexity better than compli­cated solutions.

Simple Rules presents a general framework de­fining what simple rules are, why they work, and the six types of rules that have proven effective across domains ranging from medicine to standup comedy. Much of the existing research on rules assumes they are fixed, either hardwired into our brains as decision-making biases or deeply embedded as social norms that defy change. One of our most surprising and important findings is that simple rules are not immutable — they can evolve in light of new evidence, shifting objectives, and changed conditions. The second half of this book provides concrete advice on how to actively develop better rules and continue to refine and improve them over time.

We started our research on complexity in the late 1990s, when Don was a professor at the London Business School, where Kathy spent a sabbatical. Kathy had just published Competing on the Edge, with Shona Brown. (Shona would go on, as senior vice president of business operations at Google, to successfully implement their ideas as the company rapidly grew from under $2 billion in 2003 to $46 billion nine years later.) Competing on the Edge argued that companies should avoid the extremes of too much or too little structure — an insight that we build upon in Simple Rules. Don was studying how complexity kept successful companies from adapting to changes in the marketplace, even when they saw the shifts coming. We came at complexity from different backgrounds — Kathy had studied science and engi­neering before switching to strategy, while Don had worked in private equity prior to entering academia — and our complemen­tary viewpoints allowed us to tackle the problem from different angles.

We began an exploration of the winning (and losing) strate­gies of companies struggling with the complexity unleashed by the Internet boom. What we found surprised us. The most suc­cessful companies did not try to match technological, competi­tive, or market complexity with complicated solutions. Instead, they identified a critical process — developing new products, for example, or prioritizing potential customers — and used simple rules to manage that process. We wrote up our findings in a Har­vard Business Review article called “Strategy as Simple Rules,” which argued that a company’s strategy does not live in thick binders on the CEO’s shelf, but in the simple rules that shape critical processes on a daily basis.

In the subsequent decade, we have expanded our inquiry be­yond business to study simple rules in a range of diverse settings, detailed in this book. In the chapters that follow, we will describe how DARPA, the secretive military organization that was behind the creation of the Internet, chooses which groundbreaking proj­ects to pursue next, and how burglars use simple rules to decide where to strike. We will explain how the most distinguished chefs in Paris protect their signature dishes; how Stanford’s brainy foot­ball team became the brutes of collegiate football; and how Don used simple rules to survive as an undersized bouncer in a biker bar. Simple rules allow locusts to congregate in thick swarms that can extend for miles, but also enable over one hundred thousand volunteer Wikipedia editors to collaborate on millions of articles, which are as reliable, on average, as those found in the Encyclo­paedia Britannica. Simple rules are not new. As we’ll show, an­cient Roman jurists used them to make judicial decisions, and the Jesuits applied them to guide the explosive growth of their young organization in the 1500s.

We draw on our own research and work with colleagues in­cluding Chris Bingham and Jason Davis, using field studies, lab­oratory experiments, and simulations that show why some kinds of rules are harder to learn than others but can have bigger pay­offs. These studies also describe how people can improve their simple rules and avoid sticking with dysfunctional ones. We also draw on research in other fields: studies of simple rules in psy­chology, economics, strategy, social biology, and medicine have yielded surprising and important insights. Simple rules help us understand why Parisians can eat a rich diet without gaining weight, while their counterparts in Chicago struggle with obesity.

Research by financial economists has shown that a simple invest­ment rule provides higher returns than complex financial models over 80 percent of the time and never loses money.

Don has road-tested simple rules with members of the Young Presidents’ Organization (YPO), a global network of twenty thousand executives who have founded or run a sizable organiza­tion before the age of forty-five. Over the past four years, highly trained teams of MBA and PhD students have worked with doz­ens of YPO companies to develop rules, document their imple­mentation, and measure their impact. The result has been the formulation of a three-step process to clarify corporate objec­tives, identify where simple rules can have the greatest impact, and then develop and refine the rules. This process has produced dramatic results (in many cases increasing profits by 20 to 50 per­cent) across a range of diverse companies, sometimes within the span of a few months. To our surprise, participants followed the same process to develop simple rules for their personal lives. In later chapters, we will describe the nuts and bolts of develop­ing simple rules for both business and personal use. We’ve also tested and refined our ideas about simple rules in the classroom — Kathy at Stanford’s School of Engineering and Don at MIT’s Sloan School of Management.

Complexity is not Destiny

Many people accept complexity as unavoidable. Consider the ex­ample of early MP3 players, which featured hideous design flaws. Popular MP3 players were designed with up to two dozen but­tons, some labeled with head-scratching titles like “exp” and “lib,” or unmarked altogether. One bestselling device had a one-touch “delete” button placed right next to the “play” button. Reading re­views of these early products, the most depressing part is not the product flaws themselves, but customers’ willingness to accept complicated interfaces as inevitable. Users believed that MP3 players had to be complicated because they integrated so many moving parts — hardware, software, various file formats, music sources, and a dizzying array of accessories.

Then came the iPod. When consumers first used the iPod’s iconic click wheel, they realized, perhaps for the first time, that even a system as gnarly as personal music could be managed with an interface that was clean, intuitive, and effective. The iPod didn’t just improve the music experience; it (together with iTunes) rev­olutionized how people listen to music on the go. At their best, simple rules do the same. Like the iPod’s click wheel, simple rules allow people to control complex systems without succumbing to complicated solutions. Simple rules address a deeply rooted hu­man desire for simplicity when dealing with a range of complex challenges ranging from the prosaic to the global.

For most of us, complexity is a problem we struggle to man­age in our own lives every day. Simple rules offer a hands-on tool to achieve some of our most pressing personal and professional objectives, from losing weight or overcoming insomnia to be­coming a better manager or a smarter investor. By limiting the number of guidelines, simple rules help maintain a strict focus on what matters most while remaining easy to remember and use. In a wide range of decisions, simple rules can guide choice while leaving ample room to exercise judgment and creativity.

As you read through this book, we hope (and suspect) that you will identify at least one, and probably more, personal and profes­sional challenges that simple rules could help you manage better.

For individuals, simple rules are a powerful tool, but for so-cial systems their benefits border on the miraculous. If you’ve ever observed a colony of ants searching for food, you’ve surely marveled at how they adapt to unexpected obstacles and coor­dinate their activities with one another without ever losing sight of their overarching objective. The ants are not directed by any central authority. Instead, their behavior emerges naturally as each ant follows a handful of rules when foraging. Many of us spend our workdays in organizations — including corporations, family businesses, schools, or not-for-profit organizations — that require coordinated action in the face of constantly shifting cir­cumstances. In the chapters that follow, we will provide examples of managers and employees who used simple rules to do their work more effectively and efficiently without relying on thick manuals of bureaucratic rules. Simple rules can also help solve some of the most daunting challenges we face as a society. This book documents thorny social problems where simple rules are currently used to great effect, and identifies challenges that could be addressed by simple rules in the future.

Fighting complexity is an ongoing battle that can wear us down. Disheartened, people tolerate complicated solutions that don’t work, or cling to overly simplistic narratives (“Climate change is a myth,” for example, or “Globalization is bad”) that deny the interdependencies characterizing modern life. Simple rules can be a powerful weapon in this fight.

Excerpted from Simple Rules: How to Thrive in a Complex World by Donald Sull and Kathleen M. Eisenhardt. Copyright © 2015 by Donald Sull and Kathleen M. Eisenhardt. Used by permission of Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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Top image credit: Taufuuu, via creative commons.