**Preface to "Systems Thinking"**

Systems thinking can be broadly considered as the activity of thinking applied in a systems context, forming a basis for fundamental approaches to multiple systems disciplines, such as systems engineering, systems science, and system dynamics. As the impact of global system interconnectivity proliferates and the complexity of human-made systems grows, the process of sense-making based on systems thinking becomes critical. This issue focuses on the nature of systems thinking as it applies to systems engineering, systems science, system dynamics, and related fields. In the twelve articles included in this Special Issue, contributors have presented approaches, models, and theoretical frameworks to deal with topics related to systems thinking for academic, disciplinary, and industrial applications.

Several articles address enhancements to systems thinking inquiry. In "Systemic Semantics: A Systems Approach to Building Ontologies and Concept Maps", a systemic and systematic framework for selecting and organizing the terminology of systemology is provided. The article shows the value in applying a systems perspective to ontology development in any discipline and provides a starting outline for an ontology of systemology.

The article "A Systematic Framework for Exploring Worldviews and Its Generalization as a Multi-Purpose Inquiry Framework" proposes a comprehensive "Worldview Inquiry Framework" that can be used across methodologies to govern the process of eliciting, documenting, and comparing the worldviews of stakeholders. This is a special case of the "General Inquiry Framework" which can be tailored for other contexts such as problem solving, product design, and fundamental research.

In "On the Architecture of Systemology and the Typology of Its Principles", an architecture for systemology is introduced, which shows how the principles of systemology arise from interdependent processes spanning multiple disciplinary fields, and on this basis, a typology is introduced, which can be used to classify systems principles and systems methods. This framework, consisting of an architecture and a typology, can be used to survey and classify the principles and methods currently in use in systemology, map vocabularies referring to them, identify key gaps, and expose opportunities for further development.

The article "Modeling Isomorphic Systems Processes Using Monterey Phoenix" describes preliminary research, as a proof of concept test, on the potential value of formalizing isomorphic systems processes (ISPs) based on systems science research using the Monterey Phoenix (MP) language, approach, and tool. It was found that using MP to formalize relationships within and among presently non-formally described ISPs yielded new insights into system processes.

"A Bibliographic and Visual Exploration of the Historic Impact of Soft Systems Methodology on Academic Research and Theory" describes a bibliometric meta-analysis of 286 relevant publications in engineering, business, and other social sciences fields. This explores the historic impacts of SSM on academic research and systems thinking in relevant publications that described or employed SSM for research during 1980–2018. Understanding the impact of SSM informs future use as a methodological approach to comprehend complex problem situations.

Other articles address systems thinking application. "Maturity Models for Systems Thinking" examines current thoughts regarding the value and pitfalls of maturity models. Principles and exemplars are identified that could guide the development of a Maturity Model of Systems Thinking Competence (MMSTC) for the varied roles people inhabit in systems contexts.

In "Systems Thinking Education—Seeing the Forest through the Trees", the development of systems thinking among engineers and engineering students is studied, including administration of a personality test for engineers with high systems thinking skills. Development of a new systems thinking study course is also presented. Engineers with certain personality traits acquire or improve their systems thinking capabilities through a gradual, long-term learning process and by acquiring the necessary tools.

Two articles address application of systems thinking to aid sustainability specifically. "Could Education for Sustainable Development Benefit from a Systems Thinking Approach?" addresses whether it could be possible to interlace education for sustainable development (ESD) and systems education to overcome the obstacles preventing the implementation of sustainability in education. The literature review identifies joint approaches to develop an instrument in the educational work toward sustainability.

In "Using Systems Thinking to Understand and Enlarge Mental Models: Helping the Transition to a Sustainable World", causal loop diagramming (CLD) is used to describe the general, prevailing citizen viewpoint and to propose a wider mental model that takes the natural world and sustainability into account. Adopting the wider mental model can help the industrialized world design better policies to achieve both national and United Nations (UN) sustainable development goals.

A related article, "Natural Systems Thinking and the Human Family", describes the human family system as a network of relationships, linking each family member to every other, responding dynamically to its environment and the conditions to which all members must adapt. Complex development of the human brain appears to have co-evolved with the interactional processes of the family. An integrative theory of human behavior offers broader explanatory and investigative pathways for understanding human activity.

In "A Systems Thinking Approach to Designing Clinical Models and Healthcare Services", systems thinking is used as an alternative strategy to designing clinical system models and healthcare services to alleviate many of the current design challenges in designing integrated services for chronic conditions. An illustrative example taking a clinical model and describing it as a system model is presented.

As another example of industrial application of systems thinking, "Conceptualizing Shadow IT Integration Drawbacks from a Systemic Viewpoint" introduces a systemic viewpoint to the research on Shadow IT. Business units can implement Shadow IT (SIT) without involving central IT. The article provides a conceptual framework for SIT integration drawbacks which classifies the drawbacks into three dimensions for practitioner use.

The breadth of topics for this issue is wide, and the common theme throughout is using systems thinking to aid sense-making for human endeavors. From theoretical frameworks to specific applications, the articles describe deep analysis and thought-provoking ideas. As product complexity escalates and interconnectivity of the human experience swells, the importance of systems thinking is apparent. We hope you enjoy this issue.

> **Cliff Whitcomb, Heidi Davidz, Stefan Groesser** *Editors*
