Critical thinking can be defined as the active, persistent, and careful consideration of any belief or supposed form of knowledge in the light of the grounds that support it and the further conclusions to which it tends.
(Alex Fisher, Critical Thinking: An Introduction.
Cambridge University Press, 2001)
Critical thinking is that mode of thinking in which the thinker improves the quality of his or her thinking by skillfully taking charge of the structures inherent in thinking and imposing intellectual standards upon them.
(Paul and Elder, 2001.
Foundation for Critical Thinking)
Critical thinking can be described as the intellectually disciplined process of actively and skillfully conceptualizing, applying, analyzing, synthesizing, and/or evaluating information gathered from, or generated by, observation, experience, reflection, reasoning, or communication. It is a guide to belief and reasonable, reflective thinking that is focused on deciding what to do or believe.