Resilient infrastructure research has produced a myriad of conflicting definitions and analytic frameworks, highlighting the difficulty of creating a foundational theory that informs disciplines as diverse as business, engineering, ecology, and disaster risk reduction. Nevertheless, there is growing agreement that resilience is a desirable property for infrastructure systems – i.e., that more resilience is always better. Unfortunately, this view ignore that the fact that a single concept of resilience is insufficient to ensure effective performance under diverse and volatile stresses. Scholarship in resilience engineering has identified at least four irreducible resilience concepts, including: rebound, robustness, graceful extensibility, and sustained adaptability.

In this paper, we clarify the meaning of the word resilience and its use, explain the advantages of the pluralistic approach to advancing resilience theory, and clarify two of the four conceptual understandings: robustness and graceful extensibility. Furthermore, we draw upon examples in electric power, transportation, and water systems that illustrate positive and negative cases of resilience in infrastructure management and crisis response. The following conclusions result:

1. Robustness and graceful extensibility are different strategies for resilience that draw upon different system characteristics.
2. Neither robustness nor extensibility can prevent all hazards.
3. While systems can perform both strategies simultaneously, their drawbacks are different.

Robust infrastructure systems fail when policies and procedures become stale, or when faced with overwhelming surprise. Extensible systems fail when a lack of coordination or exhaustion of resources results from decompensation. Consequently, resilience is found neither only in robustness, nor only in extensibility, but in the capacity apply both and switch between them at will.

The resilience of infrastructure essential to public health, safety, and well-being remains a priority among Federal agencies and institutions. National policies and guidelines enacted by these entities call for a holistic approach to resilience and effectively acknowledge the complex, multi-organizational, and socio-technical integration of critical infrastructure. However, the concept of holism is seldom discussed in literature. As a result, resilience knowledge among disciplines resides in near isolation, inhibiting opportunities for collaboration and offering partial solutions to complex problems. Furthermore, there is limited knowledge about how human resilience and the capacity to develop and comprehend increasing levels of complexity can influence, or be influenced by, the resilience of complex systems like infrastructure. The above gaps are addressed in this thesis by 1) applying an Integral map as a holistic framework for organizing resilience knowledge across disciplines and applications, 2) examining the relationships between human and technical system resilience capacities via four socio-technical processes: sensing, anticipating, adapting, and learning (SAAL), and 3) identifying an ontological framework for anticipating human resilience and adaptive capacity by applying a developmental perspective to the dynamic relationships between humans interacting with infrastructure. The results of applying an Integral heuristic suggest the importance of factors representing the social interior like organizational values and group intentionality may be under appreciated in the resilience literature from a holistic perspective. The analysis indicates that many of the human and technical resilience capacities reviewed are interconnected, interrelated, and interdependent in relation to the SAAL socio-technical processes. This work contributes a socio-technical perspective that incorporates the affective dimension of human resilience. This work presents an ontological approach to critical infrastructure resilience that draws upon the human resilience, human psychological development, and resilience engineering literatures with an integrated model to guide future research. Human mean-making offers a dimensional perspective of resilient socio-technical systems by identifying how and why the SAAL processes change across stages of development. This research suggest that knowledge of resilient human development can improve technical system resilience by aligning roles and responsibilities with the developmental capacities of individuals and groups responsible for the design, operation and management of critical infrastructures.