Systems Engineering: Systems Theory (Definitions)

"Systems theory pursues the scientific exploration and understanding of systems that exist in the various realms of experience, in order to arrive at a general theory of systems: an organized expressing of sets of interrelated concepts and principles that apply to all systems." (Béla H Bánáthy, "Systems Design of Education", 1991)

"Systems theory is an interdisciplinary field of science concerned with the nature of complex systems, be they physical or natural or purely mathematical." (Thomas B Sheridan, The System Perspective on Human Factors in Aviation, 2010) 

"Systems theory is the interdisciplinary study of systems in general, with the goal of elucidating principles that can be applied to all types of systems at all nesting levels in all fields of research. The term does not yet have a well-established, precise meaning, but systems theory can reasonably be considered a specialization of systems thinking; alternatively as a goal output of systems science and systems engineering, with an emphasis on generality useful across a broad range of systems (versus the particular models of individual fields)." (Gabriela Walker & Elizabeth Pattison, "Using Bronfenbrenner's Ecological Framework to Design Support Systems for Education and Special Education: Learning About Thought Systems", 2016)

"The assumption that quality of a part of a system can only be understood in its relationship to the whole and investigating the parts in isolation cannot explain their combined effect on the whole system." (Margaret S Suubi, "Education for Sustainable Development (ESD) in Higher Education", 2019) 

"Framework of describing how smaller, multiple units and components work together to create a larger system that is designed to carry out a particular function or meet a certain goal." (RaMonda Horton, "Systems-Based Approaches to Speech-Language Pathology Service Delivery for School Age Children", 2020)

"Is an interdisciplinary study of systems that takes a holistic approach to analysis that focuses on the elements within a system, how they interrelate, how they work over time and within the context of larger systems (e.g., natural or man-made)." (Tatiana C Valencia & Stephanie J Valencia, "Cultivating Flow and Happiness in Children", 2020)

"Systems theory is an interdisciplinary theory about the nature of complex systems in nature, society, and science. It is a framework by which one can use to study, investigate and describe any group of objects that work in collaboration towards a common purpose/goal."

(Cheryl M Cordeiro et al, "Culture From a Value Systems Perspective", 2020)

"The domain of systems inquiry that explores the principles and the description models of the abstract organization of phenomena, in an interdisciplinary manner and independently of their nature (natural or social systems) or scale of existence." (Evangelos C Papakitsos et al, "The Challenges of Work-Based Learning via Systemic Modelling in the European Union", 2020)

"Theory that holds that systems in nature are holistic, interconnected and interdependent. If a change occurs in one part of a system, other parts of the system are affected as well." (Joe Monaco & Edward W Schneider, "Building Performance Systems That Last", 2020)