The concept of critical thinking has been developing for the past 2500 years but the term critical thinking emerged in the mid 20th century. According to B. K. Beyer in Critical thinking (1995), critical thinking is a mode of thinking about any subject, content or problem in which one uses criteria to judge the quality of the subject and assess its validity. Other definitions put emphasis on the metacognition factor, saying that critical thinking is a way to think about one's thinking with the aim to identify its strengths and weaknesses and eventually improve its quality. According to Richard Paul and Linda Elder in The Miniature Guide to Critical Thinking Concepts and Tools (2008), critical thinking can be shortly described as a self-directed, self-disciplined, self-monitored and self-corrective mode of thinking.
In an article in volume 22 of the journal Teaching of Psychology from 1995, C. Wade identified eight characteristics of critical thinking. According to Wade, critical thinking is based on asking questions, defining a problem, examining evidence and analyzing assumptions. In addition, a critical thinker avoids emotional reasoning and oversimplification, while considering other interpretations and tolerating ambiguity.
According to the Foundation for Critical Thinking, a well-cultivated critical thinker has several characteristics. First, he or she raises questions of vital importance and formulates them in a clear and precise manner. Second, a critical thinker gathers relative information, which is then assessed and interpreted in order to reach well-reasoned conclusions and solutions. These conclusions should be tested, using relevant criteria and standards. Third, a critical thinker thinks in an open-minded way and communicates effectively with others.
Teaching critical thinking is of great importance in the current age when one has access to an enormous amount of information through technology. Students are often passive receptors of information so they need to be taught how to weed through the information and decide what is important. Critical thinking can be applied both to students' academic studies and to solving complex problems in life. Critical thinking enables people to make sound decisions on personal and civic level, which is of crucial importance for living successfully in a democracy.
In volume 22 of the journal Teaching of Psychology from 1995, which was dedicated to the teaching of critical thinking, different authors shared several strategies to help promote critical thinking. A teacher can use ongoing classroom assessment to enhance and monitor students' critical thinking. For example, students can be asked questions such as "What was the most important thing you learned in today's class?" or "What question related to this session remains uppermost in your mind?" Another strategy to foster critical thinking is to put students in group learning situations where they can get continuous support and feedback from both the teacher and other students.
The case study/discussion method is a method in which the teacher presents a case and encourages students to reach a conclusion by leading them into a discussion via prepared questions. Critical thinking can also be enhanced through so-called conference style learning. Here the teacher does not give lectures but rather acts as a facilitator of a conference, he or she gives the students the task to thoroughly read certain materials and then discuss the materials in class asking each other questions. Although the teacher does not have an active role of lecturer, he or she helps direct the discussion.
Some scholars see writing assignments in which one must defend both or more sides of an issue as a basic way to develop critical thinking skills in students. Other scholars advise teachers to produce much ambiguity in the classroom by giving students conflicting information, thereby making them think critically in order to find their way through.
Another good method to foster critical thinking is to stimulate discussions in the classroom. This can be done by asking students to read and analyze written dialogues in small groups, asking them to decide which viewpoint is the most reasonable by looking for biases, presence or exclusion of important evidence, alternative interpretations, errors in facts and reasoning. Then each group has to act out their dialogue and explain their analysis. Another way to stimulate discussions among students is to give a group of students roles to play in a discussion (such as leader, information giver, opinion seeker and disagreer) and then ask the rest of the students to find out who plays which role using the same kind of analysis as in the previous example.