I keep getting asked why DNA are systems thinkers..... we are not....very simply, a system is a collection of parts and subsystems integrated to accomplish an overall goal such as system of people is an organization.

"Systems have input, processes, and outputs with ongoing feedback among these various parts. If one part of the system is removed, the nature of the system is changed." 

Systems of course range from very simple to simple to very complex. There are numerous types of systems. For example,  biological systems, mechanical systems, human 'systems' or bio-metrics, ecological systems, and social systems.

Complex systems, which DNA operates in is of course a system, a social system comprised of numerous subsystems, but quite different to the above. These subsystems are arranged in hierarchies, and integrated to accomplish the overall goal of the overall system. But this is where the simularity ends as each human, human subsystem has its own boundaries of sorts, which is movable, unclear and co-evolving and includes various inputs, processes, outputs and outcomes geared to accomplish an overall goal for the subsystem. Yet the outcome, goals are often unclear, unknown until after the event.

A pile of sand is not a system nor is a Human system (human). If one removes a sand particle, you've still got a pile of sand. Yet its different. However, a functioning car is a system. Remove the carburetor and you've no longer got a working car.

It scares me to find managers now diagnose problems, not by examining what appear to be separate pieces of the organization, but by recognising larger patterns of interactions. Managers maintain perspective by focusing on the outcomes they want from their organizations, yet these outcomes are almost always unknown. Most managers focus on the structures that create behaviors that determine outcomes rather than reacting to events as which is mostly done in good organisations.