It is an admirable educational goal for citizens of a democracy, and one that has been advocated in the United States since Jefferson. The ability to think critically is a goal that is likely to be accepted by all American educational theorists. But it is a goal that can easily be oversimplified and sloganized.
In the progressive tradition that currently dominates our schools, "critical thinking" has come to imply a counterpoise to the teaching of "mere facts," in which, according to the dominant caricature, sheep-like students passively absorb facts from textbooks or lecture style classrooms. Critical thinking, by contrast, is associated with active, discovery learning and with the autonomous, independent cast of mind that is desirable for the citizens of a democracy. Conceived in this progressive tradition, critical thinking belongs to the formalistic tool conception of education, which assumes that a critical habit of thought, coupled with an ability to read for the main idea and an ability to look things up, is the chief component of critical-thinking skills.
This tool conception, however, is an incorrect model of real-world critical thinking. Independent-mindedness is always predicated on relevant knowledge: one cannot think critically unless one has a lot of relevant knowledge about the issue at hand. Critical thinking is not merely giving one's opinion. To oppose "critical thinking" and "mere facts" is a profound empirical mistake. Common sense and cognitive psychology alike support the Jeffersonian view that critical thinking always depends upon factual knowledge.
and Why We Don't Have Them.