The problem here is that Literature != Liberal Arts, even though some wish to classify it as such. A Liberal Arts degrees should require Philosophy I and II, Ethics, Logic, and Symbolic Logic. Not that long ago, the heavy focus on Philosophy was what defined the degree.
If a person has Liberal Arts degree with all of the Philosophy classes they do get better at critical thinking and detecting irrational and illogical thought. Just like a person with a Math degree gets better at solving equations. I have a degree in both Liberal Arts and Mathematics, and yes my Liberal Arts required everything I stated above.
A "STEM" degree on it's own presents some basic critical thinking problems, as I would say all education does. These are not exercises focused on critical thinking in a broad sense, but rather linear logic. "Critical thinking" in a traditional sense is not the same as the critical thinking in Math. For example, in politics one must take into account human nature, which is a variable set of rules. People often lie, tell partial truths, and use broken logic to make conclusions. Critical thinking in Math always works toward a single mathematical truth. With that in mind, a person can be very intelligent in programming logic, but be very poor in overall critical thinking abilities.