The "hardest" major depends on your opinion. Personally I would say math, engineering, physics or chemistry are the hardest majors, because I'm not especially good at those subjects and don't enjoy them. I can write a 20 page essay no problem, but I can't do a problem set to save my life. On the other hand, at my school there were a handful of required writing classes, as with most colleges. I knew an electrical engineering major who could blaze through supremely difficult problem sets, but was just incapable of putting together a passable essay. He flunked (and had to retake) each of the writing classes multiple times.