What are we looking at?
How is “defining” a system different from “analysing” it, and why define first?
Why do we need definition?
Sometimes, before doing anything, we have to know exactly what we are dealing with. Many errors of analysis and design go back to a wrong or incomplete definition of the system. Defining means drawing a thing’s boundary: until we know what the system is, what parts it has and what it differs from, we can’t analyse it properly or improve it.
Aristotle, in the Topics (Book I, chapter 5), takes a definition to be an account that signifies a thing’s essence: it should say what the thing is and what sets it apart, not just give a name or an accidental feature. Russell Ackoff, one of the founders of systems thinking in management, gave in 1971 an explicit definition of “system”: a set of two or more elements that satisfies three conditions; the behaviour of each element affects the behaviour of the whole, the behaviour of each element and its effect depends on the behaviour of at least one other element, and every subset of elements affects the whole while none of them acts independently of the rest. (Both are paraphrased.)
So defining is the first step of analysis, not a merely theoretical job, and the definition of “system” itself makes a precise claim: a set of components that are not independent of each other.
What does each ask?
| Difference | Definition | Analysis |
|---|---|---|
| Aim | Fix the boundary and nature of the system | Understand components, relations, functions and behaviour |
| Tools | Precise language and key features | Diagrams, questions, models and scenarios |
| Output | A short but complete description of what the system is | A set of insights and data for decision or design |
Put simply: definition asks “what is this system?” and analysis asks “how does it work? why is it like this? how can it be better?”
How does definition help design?
Suppose we want to upgrade a university. If we don’t know exactly what a “university” is, what its purpose is and what it includes, every design is groundless. Definition is the project’s first map: it fixes the goals, shows the main components, sets the boundary between the system and its environment and makes the relations between components understandable. Without it we may overlook part of the system, or analyse something that isn’t part of it at all.
A few examples
| System | Boundary | Purpose | Components | Relations |
|---|---|---|---|---|
| University | All higher-education structures known as universities | Producing knowledge, educating students, scientific research | Professors, students, classes, research institutes, financial and administrative resources | Students learn from professors, professors define research projects, funds are distributed among units |
| Dairy farm | The premises where cattle are raised | Producing milk, meat and dairy products | Cows, workers, vet, milking machines, troughs and water | The vet checks the animals’ health, the worker feeds, the milking machine collects the product |
| Post | The organisation that sends and receives mail | Carrying and distributing parcels and letters | Counters, staff, tracking system, warehouse, vehicles | The counter receives items, the warehouse sorts, vehicles transport |
| City traffic | The infrastructure and processes of vehicle flow inside the city | Managing and smoothing movement, cutting accidents and travel time | Cars, lights, streets, signs, traffic police, navigation software | Drivers use routes, lights direct the flow, police keep order |