YAGNI - You Ain't Gonna Need It. The idea behind YAGNI is to program for your requirements, not for prospective, potential features. The premise is that by keeping to what you need to program, you will (among other things) cut code bloat, reduce complexity, avoid feature creep, and reduce the restrictions on what can be done (and how it can be done) in the future.

I suppose it works in tandem with modular design: Future features can be augmented without redesigning existing code.