Explaining Complexity in Software Development?

BMazurek asks: "I'm stumped by how to explain software development complexity (not theoretical big-O notation, that's easy) to non-developers. When it comes to people who aren't in the code, my explanations fall flat. It's not that the people I'm talking to are stupid, they're quite honestly people at the top of their respective (non-tech) fields. How do -you- explain software development complexity to non-developers? What analogies do you use?" "I often try the famous Fred Brooks, Jr. quote (seldom to much success):

'Software entities are more complex for their size than perhaps any other human construct because no two parts are alike (at least above the statement level). If they are, we make the two similar parts into a subroutine--open or closed. In this respect, software systems differ profoundly from computers, buildings, or automobiles, where repeated elements abound.'

Comments

My analogy

[Rosco P. Coltrane]

When it comes to people who aren't in the code, my explanations fall flat.

Before I changed line of work (I'm not a computer professional anymore thank goodness), I used to explain my work like this:

See, what I do is programming. Programming is like writing a cooking recipe, only slightly more complex but not much more. But it's a very large recipe, and it relies upon many more recipes to make an actual dish (the program). Many cooks write recipes in different languages separately, and all we cooks have to coordinate to prepare the final dish. So we need chief cooks (managers) that call meetings and prepare Gantt charts to do that. Then sometimes a cook writes a recipe that has the wrong combination of ingredients, or that make no sense to describe how to prepare food (bugs), so we need tasters (QA) to tell us busy cooks if the overall result will be pleasing to the restaurant's customers. In the end, you get a huge dish that has some nasty morsels in it, as well as tasty ones. We then have to refine the dish so the nastyness goes away and more goodness goes in (new versions). etc etc...

The cooking recipe analogy has always worked great to explain what I did.