Peter Checkland

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'.

— Peter Checkland

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.

— Peter Checkland

A methodology will lack the precision of a technique but will be a firmer guide to action than a philosophy. Where a technique tells you 'how' and a philosophy tells you 'what', a methodology will contain elements of both 'what' and 'how'.

— Peter Checkland

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

— Peter Checkland

The core of a root definition of a system will be a transformation process (T), the means by which defined inputs are transformed into defined outputs. The transformation will include the direct object of the main activity verbs subsequently required to describe the system.

— Peter Checkland

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.

— Peter Checkland

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'. ..

— Peter Checkland

In an unrestricted science such as biology or geology, the effects under study are so complex that designed experiments with controls are often not possible. Quantitative models are more vulnerable and the chance of unknown factors dominating the observations is much greater.

— Peter Checkland

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.

— Peter Checkland