To gauge summative performance authentically, the CLA presents realistic problems that require students to analyze complex materials and determine the relevance to the taskThat's from the test-makers' website. If that makes little sense to you, there is an example here. As far as I can see, the test requires you to think sensibly about a problem and then write clearly about it. If schools want their students to do well on such tests, I would think they should have them all take at least one course in critical thinking and consider making this test the final exam. There's your incentive. (The course should be taken before the last semester of senior year, too.) More courses in philosophy and English would almost certainly help too. I doubt many people will suggest this, though, and those who do will likely be philosophers and professors of English. Oh well.
UPDATE: There is a good discussion of the book and the test it's based on here. And more here. I'm not sure about the idea that we don't evaluate student learning though. Assessment is rife at VMI, and I hear similar things about other schools. In my department we (try to) measure the improvement in critical thinking skills of students who get a minor in Philosophy (we don't offer a major), and we (try to) measure the same thing plus general knowledge of Psychology for all our Psychology majors. My sense is that this kind of thing is pretty standard. Maybe I'm wrong.