I couldn’t agree more with Ken Orr’s remarks about the vague usage of terms that one might expect to have clearly-defined meanings. But this is what you must expect at the interface between the worlds of human enterprise and scientific precision.
There is a theory – which I find intuitively plausible – that natural language evolved largely to help people inspire and motivate others. Or, if you prefer to look at things that way, to manipulate and exploit them. Wherever you see natural language (English, French, Russian, etc.) being spoken under normal everyday conditions, you will see brands being talked up, deals offered, and haggling engaged in. Right from childhood, “smooth talkers” have a definite advantage: they can persuade others to do what they want, and often acquire groups of admirers and hangers-on. With adulthood, the horizons widen: a persuasive speaker can sell cars or insurance, get a good job or a promotion, attract friends and lovers, or rapidly climb the greasy pole of political ambition.
Those who get to the top – whether as our political masters, as captains of industry, or otherwise – instinctively trust their natural ability to make a persuasive case, convert others to their point of view, and (if the worst comes to the worst) to talk their way out of hot water.
One thing that they have difficulty coping with, or even understanding, is the unemotional, objective, matter-of-fact language of science and technology. Hearing an engineer present some plain facts and figures, the manager or politician finds himself continually asking, “Why did he say that? What’s his motive in making this claim? What’s in it for him?”
This fundamental contrast is the key running gag that makes Scott Adams’ Dilbert cartoon series so funny. The pointy-haired boss rarely opens his mouth without trying to making himself look good, do others down, or strive for dominance. So he is utterly baffled by the strange tribe of engineers, who make a religion of rigorous, objective precision and who habitually tell the truth without concern for their own personal benefit. They, in turn, are confused and disgusted by his obvious self-seeking and the degrading dishonesty it leads him into.
So, whenever we come across a term like “use case”, it is useful to consider not just what it ought to mean, but the personal agendas of people who seem to be abusing it or stretching its meaning.
No doubt when software engineers and designers talk about use cases, they are pretty clear about what they mean and what they are trying to accomplish.
But as soon as some “users” – anyone other than those who introduced the term because they found it helpful – pick it up and start to bandy it about, the motivation changes. Instead of trying to communicate as clearly as possible, eliminating all possible sources of confusion or ambiguity, we must realize that some people may be doing the exact opposite.