This debate comes up a lot in college. I got a 3.9 in Philosophy and Political Science (I actually thought Philosophy was a billion times harder than Political Science...besides the point). I love how people in the School of Business and the Engineering would imply, "Well, your GPA is so high because you're a Liberal Arts major."
But these same people have a 2.6 in engineering. It is not the GPA that makes them look foolish...its the fact that they were dumb enough to take something you're not good at. If you have a 2.6 in Engineering but it is good enough to get an engineering job...GREAT. But don't knock on us because we actually took something we can do well in. It was your choice to take engineering. If law school was an option, you should have researched the importance of grades before choosing it. Why should we be punished because we were smart enough to avoid something we would get a 2.6 in?
The average GPA at my engineering undergrad was a 2.6 while the average GPA at a liberal arts college it is usually 3.2-3.4. Thus, you cannot compare the GPAs directly since the two programs are obviously curved differently. It's not that engineers aren't as good at engineering as you are at polisci, but that the programs are graded differently.
One of the large differences in difficulty between science/engineering and liberal arts is the difficulty of the Gen ed courses required. For science/engineering, the math gen eds were generally Calc I, Calc 2, Calc 3, DiffEq, and Linear Algebra while the liberal arts majors could take fluff math (i.e. "Qualitative Business Statistics") and have it count. The same is generally true for science gen eds, as science/engineering majors have to take calculus-based Physics 1 & 2 and Chem 1 & 2, while liberal arts majors can take "Rocks for Jocks." IME, the liberal arts gen ed requirements were usually more consistent across the board, consisting of classes such as "Freshman Composition" and "Introduction to Literature."
Regardless, the OP isn't going to Columbia with a 2.6/158.