The world around us is a complex web of relationships connecting people, companies, countries, cells, or species into a system that provides the context for our daily existence. Given this complexity, it is hard to imagine any interesting problem that can be solved in isolation, i.e. without taking into consideration the adequate representation of both system constituent components and their mutual influences. Under such circumstances, it is imperative that our policies at all levels (local, state, country, the world), intended to regulate such systems, take into consideration this richness of both relevant system elements and relationships among them.

Events get even more complicated when we are faced with natural and social systems that include transitions and oscillations among their various phases. A new phase begins when the system reaches a threshold that marks the point of no return. These threshold effects are found all around us. In economics, this could be movement from a bull market to a bear market; in sociology, it could be the spread of political dissent, culminating in rebellion; in biology, the immune response to infection or disease as the body moves from sickness to health; in ecology, it could be an unchecked growth of species due to the removal of a top-level predator in the system; in healthcare, it could be an uneven access to services due to the poorly devised policy regulating health insurance policies. Companies, societies, markets, or humans rarely stay in a stable, predictable state for long. Randomness, power laws, and human behavior ensure that the future is both unknown and challenging.

How do events unfold? When do they take hold? Why do some initial events cause an avalanche while others do not? What characterizes these events? What are the thresholds that differentiate a sea change from insignificant variation? And, most importantly, what can we do at the policy level to promote activities that will bring about positive, long-term, and sustainable changes in the system of interest?

Many methods and techniques have been developed to deal with the complexity of systems, including systems dynamics, fractals, chaos theory, science of networks, and complexity theory. They provide a powerful set of tools to model and/or simulate phenomena that are characterized by their scale-free and/or small-world network structure, sensitivity to initial conditions, power-law distributions, adaptability, self-organization, feedback loops, and emergent properties. However, applying such tools on any real-world problem will require the mastery of intricacies of both public policy and a wide variety of discipline-specific expertise, working together to uncover principles that both transcend and complement disciplinary contributions.

Consequently, the Journal of Policy and Complex Systems focuses on providing the platform where policy makers, experts in relevant disciplines, and modelers will come together to offer scientifically valid and societally appropriate solutions to the most challenging problems facing the world today.