This section summarises the theories of critical thinking upon which we based our content analysis method, for those who have not yet read the methodology paper (Newman et al. 1995).

Garrison developed a theory of critical thinking, as a kind of problem-solving process (Garrison 1992). Critical thinkers move through 5 stages, identifying a problem, defining it more clearly, exploring the problem and possible solutions, evaluating their applicability, and then integrating this understanding with existing knowledge. Although he initially developed it as a means of studying individual distance learners, it is well suited to the analysis of critical thinking within group learning, since these same stages are followed.

Henri (1991) identified five dimensions for analysing Computer-Mediated Communication (CMC): participative, social, interactive, cognitive and metacognitive. Questions of deep learning and critical thinking are in the cognitive dimension, so we concentrated on that. She laid out 5 skills needed for critical reasoning. It turns out that each skill is used mainly in one of Garrison's stages, as Table 1 shows.

Table 1. Stage and skills in the critical thinking process
Garrison's CT stagesHenri's critical reasoning skills
1. Problem identification
a triggering event arouses interest in a problem
Elementary clarification
observing or studying a problem, identifying its elements, observing their linkages
2. Problem definition
define problem boundaries, ends and means
In-depth clarification
analysing a problem to understand its underlying values, beliefs and assumptions
3. Problem exploration
ability to see to heart of problem based on deep understanding of situation
admitting or proposing an idea based on links to admittedly true propositions
4. Problem applicability
evaluation of alternative solutions and new ideas
making decisions, evaluations and criticisms
5. Problem integration
acting upon understanding to validate knowledge
for application of solution following on choice or decision

For each stage, Garrison, Henri and us identified indicators that showed (or at least suggested) critical thinking was taking place. For the content analysis, we picked pairs of indicators: a +ve indicator, showing evidence of critical thinking, and a -ve indicator, showing its opposite (e.g. uncritical acceptance or denial, deviations from the subject). These are discussed in detail in the earlier paper, and listed in Appendix A, where we show how we think they map into Garrison's 5 stages of critical thinking.