Foundations of Systems Engineering

SEBOK Part 2 is a guide to knowledge associated with system , particularly knowledge relevant to Systems Engineering (SE). This knowledge is included in the SEBoK to help systems engineers benefit from an understanding of the broader context for their discipline, in terms of theories and practices of systems science and other fields of systems practice. It is also hoped that by including the wider Systems Science context of SE we will make SE knowledge more accessible to a wider audience outside of its traditional domains.

To download a PDF of Part 2, please click here.

Knowledge Areas in Part 2: Systems

Part 2: Systems, contains the following knowledge areas:

Introduction

Most systems engineers are practitioners, applying processes and methods that have been developed and evolved over decades. SE is a pragmatic approach, inherently interdisciplinary, yet specialized. Systems engineers usually work within a specific domain, using processes and methods that are tailored to their domain’s unique problems, constraints, risks and opportunities. These processes and methods have been found to capture domain experts’ knowledge of the best order to tackle issues as a problem in the particular domain is approached.

Specific domains in which systems approaches are used and adapted include

Technology products, integrating multiple engineering disciplines
Information-rich systems, e.g. command & control, air traffic management etc
Platforms, e.g. aircraft, civil airliners, cars, trains, etc
Organisational and enterprise systems, which may be focused on delivering service or capability
Civil engineering/infrastructure systems, e.g. roads networks, bridges, builds, communications networks, etc.

The specific skill-sets for each domain and system scale may be quite different. However there are certain underlying unifying principles based on systems science and systems thinking that will improve the effectiveness of the systems approach in any domain. In particular, shared knowledge of systems principles and terminology will enable communication and improve our ability to integrate complex systems that span traditional domain boundaries (Sillitto 2012). This integrated approach is increasingly needed to solve today’s complex system challenges, but as these different communities come together they can find that assumptions underpinning their world-views are not shared.

To bridge between different domains and communities of practice, we need a well-grounded definition of the “intellectual foundations of systems engineering”, and a common language to describe the relevant concepts and paradigms. We need to look beyond systems engineering to achieve this. An integrated systems approach for solving complex problems needs to combine elements of systems science, systems thinking and systems approaches to practice, ranging from the technical-systems focus that has been dominant in systems engineering to the learning-systems focus of social systems intervention. An integrated systems approach needs to provide a framework and language that allow different communities, with highly divergent world-views and skill sets, to work together for a common purpose.

The Systems Praxis Framework

The term “systems praxis” refers to the entire intellectual and practical endeavour for creating holistic solutions to today’s complex system challenges. praxis is defined as “putting theories into action” [SOURCE], the best holistic approach to a given complex challenge may require integrating appropriate theory and appropriate practice from a wide variety of sources. Systems praxis requires many communities to work together. To work together we must first communicate; and to communicate, we must first connect.

This summary of a Praxis Framework is included here because it represents current thinking on the intellectual foundations of systems engineering and associate common language to make the concepts and principles of systems thinking and practice accessable to anyone applying a systems approach to engineered system problems. This framwork and thinking have been used to help organize the guide to systems knowledge in the SEBoK.

The Praxis Framework for unifying systems praxis was developed by members of INCOSE and ISSS (IFSR 2012) as the first step towards a “common language for systems praxis”. The diagram below shows the flows and interconnections among elements of a “knowledge ecosystem” of systems theory and practice.

In this framework, the following elements are connected:

systems thinking is the core integrative element of the framework. It binds the foundations, theories and representations of systems science together with the hard, soft and pragmatic approaches of systems practice. In systems praxis, as in any practical discipline underpinned by science, there is constant interplay between theories and practice, with theory informing practice and outcomes from practice informing theory. Systems thinking is the ongoing activity of assessing and appreciating the systems context, and guiding appropriate adaptation, throughout the praxis cycle.

Interdisciplinary systems science has a very wide scope and is grouped into three broad areas:

Foundations, which help us to organize knowledge, learning and discovery, and include: meta-theories of methodology; ontology; epistemology; axiology; praxiology (theory of effective action); teleology, semiotics & semiosis; category theory; etc.
Theories about systems, abstracted from domains and specialisms so as to be universally applicable: general systems theory; systems pathology; complexity; anticipatory systems; cybernetics; autopoiesis; living systems; science of generic design; organization theory; etc.
Representations and corresponding theories we can use to describe, explore, analyse, and make predictions about systems and their wider contexts, whether in terms of models; dynamics; networks; cellular automata; life cycles; queues; graphs; rich pictures; narratives; games and dramas; agent-based simulations; etc.

Systems Approaches to practice aim to act on the real world to produce desired outcomes without adverse unintended consequences; so practice needs to draw on the wide range of knowledge appropriate to the system of interest and its wider context. No one branch of systems science or practice provides a satisfactory explanation for all aspects of a typical system “problematique”, a more pragmatic approach is needed. Traditional systems approaches are often described as either:

Hard methods are suited to solving well-defined problems with reliable data and clear goals, using analytical methods and quantitative techniques. Strongly influenced by “machine” metaphors, they focus on technical systems, objective complexity, and optimization to achieve desired combinations of emergent properties. They are based on “realist” and “functionalist” foundations and worldview.
Soft methods are suited to structuring problems involving incomplete data, unclear goals, and open inquiries, using a “learning system” metaphor; focus on communication, subjective complexity, interpretations and roles; and draw on subjective and “humanist” philosophies with constructivist and interpretivist foundations.

Pragmatic (or Critical) approaches judiciously select an appropriate set of tools and patterns that will give sufficient and appropriate insights to manage the issue at hand, applying multiple methodologies drawn from different foundations as appropriate to the situation. Heuristics, boundary techniques, model unfolding, etc, enable a deep understanding of assumptions, contexts, and constraints, including complexity due to different stakeholders’ values and valuations. An appropriate mix of “hard” “soft” and custom methods draws on both systems and domain-specific traditions. Systems may be viewed as networks, societies of agents, organisms, ecosystems, rhizomes, discourses, machines, etc.

The set of “clouds” that collectively represents systems praxis is part of a wider ecosystem of knowledge, learning and action. Successful integration with this wider ecosystem is key to success with real world systems. Systems science is augmented by “hard” scientific disciplines such as physics and neuroscience, and by formal disciplines such as mathematics, logic and computation; it is both enhanced by, and used in, humanistic disciplines such as psychology, culture, and rhetoric, and pragmatic disciplines, such as accounting, design, and law. Systems practice depends on measured data and specified metrics relevant to the problem situation and domain; on solicitation of local values and knowledge; and on pragmatic integration of experience, legacy practices, and discipline knowledge.

So in summary: Integrative Systems Science allows us to identify, explore and understand patterns of complexity through contributions from the foundations, theories and representations of systems science and other disciplines relevant to the “problematique”. Systems Approaches to practice address complex problems and opportunities using methods, tools, frameworks, patterns, etc, drawn from the knowledge of integrative systems science, while observation of the results of systems practice enhances the body of theory. Systems Thinking binds the two together through appreciative and reflective practice using systems concepts, principles, patterns, etc.

Scope of Part 2

Part 2 of the SEBoK contains a guide to knowledge about systems, which is relevant to a better understanding of systems engineering. It does not try to capture all of this systems knowledge here; rather, it provides an overview of a number of key aspects of systems theory and practice especially relevant to SE.

The organization of knowledge in Part 2 is based around the Praxis Framework discussed above (IFSR 2012). Indeed, the need to develop a clear guide to the underpinning knowledge of SE was one of the motivations behind the praxis framework. It is expected that the coverage of systems knowledge will be significantly increased in future versions of the SEBoK as this work progresses.

The following diagram summarizes the way in which the knowledge in SEBoK Part 2 is organized.

Figure 2. The relationships between key systems ideas and Part 2 Knowledge Areas. (SEBoK Original)

The diagram is divided into five sections, each describing how we have treated systems knowledge in the SEBoK.

The Systems Fundamentals Knowledge Area considers the question “What is a Systems? It explores the wide range of system definitions and considers open system , System Types, Groupings of Systems, complexity , and emergence . All of these ideas are particularly relevant to engineered system and to the groupings of such systems associated with the Systems Approach applied to Engineered Systems (i.e. product system , service system , enterprise system and system of systems (sos) Capability).
The Systems Science Knowledge Area presents some influential movements in systems science, including the chronological development of systems knowledge and underlying theories behind some of the approaches taken in applying systems science to real problems.
The Systems Thinking Knowledge Area describes key Concepts, Principles and Patterns shared across systems research and practice
The Representing Systems with Models Knowledge Area considers the key role that abstract models play in both the development of system theories and the application of Systems Approaches.
The Systems Approach Applied to Engineered Systems Knowledge Area defines a structured approach to problem/opportunity discovery, exploration, and resolution, that can be applied to all engineered systems . The approach is based on systems thinking and utilizes appropriate elements of system approaches and representations. This KA provides principles that map directly to SE practice.

Systems Thinking is a fundamental paradigm describing a way of looking at the world and People who think and act in a systems way are essential to the success of both research and practice. In particular, individuals who have an awareness and/or active involvements in both research and practice are needed to help integrated these closely related activities.

The knowledge presented in this part of the SEBoK has been organized into these areas to facilitate understanding, the intention is to present a rounded picture of research and practice based on system knowledge. These knowledge areas should be seen together as a “system of ideas” for connecting research, understanding, and practice, based on system knowledge which underpins a wide range of scientific, management, and engineering disciplines and applies to all types of domains.

References

Works Cited

International Federation for Systems Research (ISFR) 2012. The Systems Praxis Framework, developed as a joint project of INCOSE and ISSS. Released under Creative Commons Attribution 3.0 License. Source is available at http://systemspraxis.org/framework.pdf.

Primary References

Bertalanffy, L., von. 1968. General System Theory: Foundations, Development, Applications, rev. ed. New York, NY, USA: Braziller.

Checkland, P. B. 1999. Systems Thinking, Systems Practice. Chichester, UK: John Wiley & Sons.

International Federation for Systems Research (ISFR) 2012. The Systems Praxis Framework, developed as a joint project of INCOSE and ISSS. Released under Creative Commons Attribution 3.0 License. Source is available at http://systemspraxis.org/framework.pdf.

Additional References

Lawson, H. 2010. A Journey Through the Systems Landscape. London, UK: College Publications, Kings College, UK.

MITRE Corporation. 2011. Systems Engineering Guide: Comprehensive Viewpoint. Accessed 2/28/2012 at http://www.mitre.org/work/systems_engineering/guide/enterprise_engineering/comprehensive_viewpoint/

MITRE Corporation. 2011. Systems Engineering Guide: Systems Thinking. Accessed 2/28/2012 at http://www.mitre.org/work/systems_engineering/guide/enterprise_engineering/comprehensive_viewpoint/systems_thinking.html

Senge, P. M. 1990. The Fifth Discipline: The Art & Practice of the Learning Organization. New York, NY: Doubleday Business.

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