A more detailed, but still uncontroversial comprehensive, definition is that philosophy is rationally critical thinking, of a more or less systematic kind about the general nature of the world (metaphysics or theory of existence), the justification of belief (epistemology or theory of knowledge), and the conduct of life (ethics or theory of value). Each of these three elements...
Anthony Quinton (born 1925) in: Ted Honderich ed. (1995) The Oxford Companion to Philosophy. New York: Oxford University Press
...the Bush regime doesn't believe in funding education because if you fund education you will have a more educated populace. If you have a more educated populace, you will have critical thinking. If you have critical thinking, you cannot push this agenda that they have and you won't have as many people that are so willing to serve in the armed forces for Dick Cheney.
The human capacity for denial and rationalization is always shocking, but never surprising.
Critical thinking is more than a set of skills and processes and there are many different skills and actions that may be involved in critical thinking; Emotion and emotional climate (two different things) are relevant and may need to be to be taken into account; Critical thinking is 'nurtured' in it's development. Nurturing might imply that it is best developed in a challenging environment which is relatively free of threat;
The purpose of critical thinking... is rethinking: that is, reviewing, evaluating, and revising thought.