"A root definition describing a notional system chosen for its relevance to what the investigator and/or people in the problem situation perceive as matters of contention."

“We reduce the complexity of the variety of the world in experiments whose results are validated by their repeatability, and we may build knowledge by the refutation of hypotheses.”

“In a certain sense human activity systems do not exist, only perceptions of them exist, perceptions which are associated with specific Ws.”

“The concept of action research arises in the behavioural sciences and is obviously applicable to an examination of human activity systems carried out through the process of attempting to solve problems. This core is the idea that the researcher does not remain an observer outside the subject of investigation but becomes a participant in the relevant human group. The researcher becomes a participant in the action, and the process of change itself becomes the subject of research. In action research the roles of researcher and subject are obviously not fixed: the roles of the subject and the practitioner are sometimes switched: the subjects become researchers... and researchers become men of action.”

“We have no aces to what the world is, to ontology, only to descriptions of the world... that is to say, epistemology... We should never say something in the world: 'it is a system'; only: "it may be described as a system'.”

“Cursory inspection of the world suggests it is a giant complex with dense connections between its parts. We cannot cope with it in that form and are forced to reduce it to some separate areas which we can examine separately'. ..”

“Making drawings to indicate the many elements in any human situation is something which has characterized SSM from the start. Its rationale lies in the fact that the complexity of human affairs is always a complexity of multiple interacting relationships; and pictures are a better medium than linear prose for expressing relationships. Pictures can be taken in as a whole and help to encourage holistic rather than reductionist thinking about a situation.”