The paper's purpose is to clarify and develop some theoretical and practical implications of the concept of critical thinking, and the field of social studies is used as one example of the problem. The work of four leading critical theorists (Robert Ennis, Harvey Siegel, Michael Scriven, and R. S. Peters) is described and a distinction is made between the holistic approach of most critical thinking philosophers and the general approach of most cognitive psychologists. A premise of the paper is that global insights into the obstacles to critical reflection, critical inquiry, and critical discussion on the part of students, teachers, and the general public are crucial to sound design of critical thinking instruction. Teachers, however, rarely grasp where and when the concept of free critical discussion is essential, what it means to conduct it, and what is required to empower students to pursue it with understanding and self-command. The origins of critical thinking in the Socratic ideal and the application of Piaget's model of the egocentric mind to uncritical thought are discussed. The paper concludes that if the need to develop long-term strategies for nurturing the development of teachers' own critical powers and passions is ignored, the emphasis on critical thinking will be a passing fad. The issue is discussed in five sections: (1) "Rational and Irrational Learning"; (2)"Thinking Critically in the Strong Sense"; (3)"The Egocentrically Critical Person"; (4)"The Sociocentrically Critical Person and the Ideal of a Critical Society"; and (5)"Social Studies and the Fostering of Rational Belief." (TRS)