Critical thinking definitions may be found at http://www.coping.org/write/percept/critical.htm

"We have always esteemed critical thinking because we have believed that a 'search for the truth' is what thinking is all about. As a result of this fallacy we have sadly neglected the generative, productive, constructive, creative and design aspects of thinking. New concepts, new perceptions, new hypotheses, new designs have to be created - they are not just discovered. We also need to realize that, far from being a difficult mental process, critical thinking is very easy because of the possibility of choosing your reference standard."

Edward de Bono, I am Right, You are Wrong, Penguin Books, 1991