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Vulnerabilities and Failures of Complex Systems

The generic product of engineering is a system. Systems interact with each other as a result of the choices of their designers, owners, and users. These complex systems of systems fail in unanticipated ways. The impacts of those system failures are amplified by the often unplanned and unappreciated interdependencies among systems. The result is an increasing frequency and magnitude of system failures that have major impacts on regional economies and on the physical well-being of the populations they serve. Compounding this concern is the emergence of malevolent acts resulting from irresponsibility, disaffected employees and users, criminal motives, terrorism, and state-supported strategic attack. This paper first examines some vulnerabilities encountered in the ‘federation’ of systems through the widespread application of information technology. It proposes a defensive design paradigm that recognizes the unavoidable occurrence of failures resulting from complexity and from malice. Finally, the implications for engineering design are examined and proposals are made for ways to introduce such an approach to design into curricula.