"Critical thinking" (most frequently known by the endlessly repeated phrase "higher-order thinking skills" or HOTS) is a particular conceit of the pretentious constructivist crowd -- a crowd averse to thinking and analysis. This crowd wallows in false dichotomies. It establishes a false dichotomy between learning subject matter and "thinking" to justify its profound hostility to knowledge. It's either one or the other. According to this crowd, "thinking" somehow can take place in a vacuum.
The saprozoic crowd's obsession with so-called higher order thinking skills has its basis in a misunderstanding of Bloom's fabled taxonomy. Bloom's taxonomy -- a scheme bandied about endlessly in ed schools -- attempts to classify levels of intellectual behavior important in learning. The scheme is viewed as a hierarchy consisting of knowledge, comprehension, application, analysis, synthesis and evaluation. This hierarchy supposedly proceeds from lower-order to higher-order thinking skills.
In this scheme, as interpreted by the constructivist crowd, knowledge and comprehension have a lowly, contemptible amoeba-like existence and may be disregarded because of their lowness in the hierarchy. This suits the anti-intellectual constructivist crowd just fine. However, I doubt that Bloom ever envisioned such an interpretation. Most likely he viewed each category as being inextricably intertwined with each other. In other words, you cannot think in a vacuum. You need something to think about. This commonsensical and pedestrian insight is beyond the grasp of the mindless, but pretentious progressive/constructivist education herd.