The following is a tangent. When designing something, there are often many choices. If they interact, it quickly becomes intractable. It's tempting to try to k

The following is a tangent. When designing something, there are often many choices. If they interact, it quickly becomes intractable. It's tempting to try to keep them in mind, and work out the answer, but with exponentially increasing complexity, your limits are quickly reached (no matter how smart you are). Enhancing your intelligence, e.g. by offloading information onto paper, also has limits. One solution is the scientific experiment: hold all variables constant, and see the effect of changing just one design choice. Holding them constant means you have made a design choice for that aspect that is almost certainly not optimal. Ideally, you can do what is suggested in the article - create modules that are largely independent, and experiment within one module in isolation. Because there are fewer variables per module, they are less complex, and it takes fewer experiments to understand how each works. The deep problem with this is if you don't know what those modules would be - i.e. you don't know which aspects are independent because that's the very thing you're trying to find out! Of course, you can probably have a guess, and certainly use your initial experiments to check those guesses, and maybe with the information gained, improve your guesses. EDIT a specification is a module, in that it separates out some design choices.