Complex systems, whether natural or engineered, are composed of many parts. But it’s not the mere number of components that makes them complex. After all, stones are composed of huge numbers of molecules, yet we would not consider them complex. A truly complex system consists of many different kinds of parts, intricate organizations and highly different structures at different levels of scale. Humans, bacteria, advanced microprocessors, modern airplanes, global enterprises, healthcare organizations and urban environments are all examples of complex systems exhibiting these massive, heterogeneous, intricate characteristics.
What makes these systems so complex? Whether they were designed by humans or evolved in nature, why aren’t they simpler? What purpose does this complexity serve?
A few years ago I heard a very interesting talk addressing these questions by Cal Tech professor John Doyle. The talk was based on a paper, Complexity and Robustness, which he co-authored with professor Jean Carlson from UC Santa Barbara.
According to Carlson and Doyle, you can find very simple biological organisms in nature, and you can design very simple objects. The key ingredient you give up is not their basic functionality, but their robustness - that is, the ability to survive, for biological organisms, or to perform well, for engineered objects - under lots of different conditions, including the failures of individual components. Robustness implies the ability to adapt and keep going in spite of a rapidly changing environment.
For example, as part of their evolution, biological organisms - from plants to mammals - have developed highly sophisticated control and regulatory mechanisms designed to help them survive in dramatically fluctuating environments. In humans these control mechanisms form the autonomic nervous system, which includes involuntary functions like breathing, digestion, heart rate and perspiration that must be carefully monitored and regulated to keep us alive.
These control mechanisms are so sophisticated, especially in higher organisms, that they generally bring along their own problems. One of the most important protection mechanisms, for example, is the immune system, which guards against disease. But the immune system is subject to its own serious diseases, such as immunodeficiencies when its activity is abnormally slow, and autoimmunities, which are caused by a hyperactive immune system.
Similarly, computers, airplanes and other advanced machines have become much more reliable over the years, including the ability to better tolerate individual component failures. Their sophisticated designs enable them to adapt to their environment and function adequately under a wide variety of conditions. But as we know, such robust machines are much more complicated than their simpler predecessors, - in their design, operations and support requirements.
About a year ago, MIT professor Nancy Leveson published Engineering a Safer World: Systems Thinking Applied to Safety, a book focused on the safety and robustness of highly complex systems. The classic approaches to safety assumed that accidents are caused by component failures or by human error. Thus making components very reliable, introducing fault tolerance techniques and planning for their failure will help prevent accidents. Similarly rewarding safe human behavior and punishing unsafe behavior will eliminate or significantly reduce accidents.
These assumptions no longer apply, especially for complex, sociotechnical systems, that is, systems that combine powerful digital technologies with the people and organizations that use and support them. Such systems not only have to deal with the complexities associated with large scale hardware and software infrastructures, but with the even more complex issues involved in human and organizational behaviors.
“For twenty years I watched engineers in industry struggling to apply the old techniques to new software-intensive systems - expending much energy and having little success,” writes Leveson. “At the same time, engineers can no longer focus only on technical issues and ignore the social, managerial, and even political factors that impact safety if we are to significantly reduce losses.”
A physical or organizational complex system can be reliable but unsafe. As systems become increasingly complex, the interactions between their components dominate the overall design. Accidents can occur from the unanticipated interactions among components which are all working fine according to their individual specifications. Moreover, because there are so many potential interactions in systems with very large number of components, it becomes practically impossible to identify or test for every possible cause of failures. So, hopefully rarely, unanticipated failures can still cause catastrophic results.
In a recently published book, Antifragile: Things that Gain from Disorder, author and professor Nassim Taleb argues that we need to go beyond robustness in designing our complex systems and institutions. Taleb goes a step beyond robustness, introducing the notion of antifragility, a property that enables systems to not only survive a major shock but to actually benefit from volatility and chaotic events. Antifragility is what enables biological systems to not just survive major changes, but to continuously evolve and come up with new mechanisms to better adapt to the changes.
In 2007 Taleb introduced the concept of black swans in his best-seller book of the same name. Taleb used black swans as a metaphor for high impact, highly consequential and hard-to-predict events that are way beyond the realm of normal expectations. These events are almost impossible to predict, but when they do arrive they can profoundly shape the course of history, such as the 9/11 attacks, the rise of the Internet, and the recent global financial crisis.
In Learning to Love Volatility, an essay published in the WSJ around the time Antifragile came out, Taleb argues that we need to learn from evolutionary biology and create antifragile infrastructures and institutions that can absorb, withstand and actually thrive under the continuing impact of black swan events. He writes:
“Fragility is the quality of things that are vulnerable to volatility. . . The opposite of fragile . . . isn't robust or sturdy or resilient - things with these qualities are simply difficult to break. To deal with black swans, we instead need things that gain from volatility, variability, stress and disorder. . .”
“As a practical matter, emphasizing antifragility means that our private and public sectors should be able to thrive and improve in the face of disorder. By grasping the mechanisms of antifragility, we can make better decisions without the illusion of being able to predict the next big thing. We can navigate situations in which the unknown predominates and our understanding is limited.”
He gives a number of examples of the value of antifragility. The airline industry does a particularly good job investigating every plane crash and learning from the experience. The restaurant industry has a relatively high failure rate, but every restaurant failure offers important lessons that strengthen all other restaurants.
“These industries are antifragile: The collective enterprise benefits from the fragility of the individual components, so nothing fails in vain. These businesses have properties similar to evolution in the natural world, with a well-functioning mechanism to benefit from evolutionary pressures, one error at a time.”
“Things that are antifragile only grow and improve under adversity. This dynamic can be seen not just in economic life but in the evolution of all things, from cuisine, urbanization and legal systems to our own existence as a species on this planet.”
Taleb concludes his WSJ essay with a personal message. He points out that exercise is good for our health precisely because we become stronger by stressing our bones, muscles and heart, - but we have not translated this insight into other domains of physical and mental well-being. By making ourselves too comfortable and trying to eliminate volatility from our lives, we make our bodies and souls fragile. “We must instead learn to gain from disorder,” he tells us. Or, as 19th century German philosopher Friedrich Neitzsche famously said, “what doesn’t kill us makes us stronger.”