When I first started out in software engineering during the ’80s, I had a talk with an older McDonnell Douglas engineer. Among his various amusing anecdotes from the Apollo moonshot era was his recounting of the Persian Rug Theory. Being wide-eyed and curious, I asked him what the heck the Persian Rug Theory was and how it pertained to software engineering.
Here’s his story: Hundreds of years ago, when Persian rugs were au courant with the social set, rug buyers were careful negotiators and would look for any reason — say, the use of two different wools– to undercut the price on a rug they were considering.
What the rug makers might learn to do — say, when making other such rugs, elegantly weaving together two different sets of raw wool whose coloring wasn’t a perfect match — would be to put in a tiny defect. It’d be off to the side and wouldn’t detract at all from the gorgeousness of the rug, but an expert eye would be sure to notice it. As the rug maker expected, the rug buyer would become fixated on this unimportant imperfection in the effort to get the best price and would thus miss completely that the coloring across the rug was just a tad off. Both maker and merchant would be happy with the final selling price, and the eventual owner at home would be happy with their Persian rug.
The Douglas gent told me that in software, when you are passionate and really believe in what you are doing, there can be times when you know the right things to do, but the powers-that-be might not have the vision. When you want to get functionality included that you know is crucial but management doesn’t understand, it’s much easier to get the functionality approved if you purposely put in a small but obvious problem. It might be a spelling error, a wrong copyright date, or an incorrect address.
Does the Persian Rug Theory actually work? Well, all I’ll say is that the theory is part of software lore, and what I build always includes all the necessary functionality. The rest I leave to you.