This post originally appeared on The Thinker on January 9, 2008.

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In an earlier post, I defined critical thinking as “the set of practices and attitudes intended to get us as close as possible to the truth.” But I’m not happy with that definition. It falls a bit short of fully capturing what critical thinking is really all about. Critical thinking is hard to define in a simple statement of meaning, and upon reflection I think a model is warranted rather than a definition.

In this post, I’d like to introduce my own working model of critical thinking. And by “working” model, I mean it works good enough for now, but I’m not completely happy with it and it’s still a work in progress.

I begin by recognizing that critical thinking involves certain cognitive skills, various characteristic habits, and specific values or commitments, as well as the relationships between these things. For the mathematically inclined, we could formally define critical thinking using set theory notation as:

CT = { {S}, {H}, {V}, {R} }

where {S} is a set of cognitive skills, {H} is a set of characteristic habits, {V} is a set of values/commitments, and {R} is a set of relationships among the sets {S}, {H}, and {V}, and/or the elements within them.

The set of cognitive skills include things like logic, analysis, evaluation, inference, reading comprehension and language skills, interpretation, explanation, and synthesis. Alternatively I could have used Bloom’s taxonomy of cognitive skills or some other list, or I could even decompose these into more specific skills. For instance, analysis can be decomposed into deconstructing, contrasting and comparing, differentiating and discriminating, etc.; synthesis can be decomposed into organizing, classifying, composing, etc.; logic can be decomposed into abduction, deduction, etc.; and so on. The point is that these are all fundamental reasoning skills, regardless of the specific list or taxonomy chosen to represent them.

Next is the set of characteristic habits. I use the term “characteristic habits” because these are the habits that characterize the critical thinker — i.e., the acquired behavior patterns that distinguish the critical thinker from the non-critical thinker. Richard Paul lists these as intellectual humility (an awareness of and willingness to admit to the prejudice of one’s viewpoint and the limits of one’s knowledge and abilities), intellectual courage (a willingness to challenge one’s own beliefs), intellectual empathy (ability and willingness to examine issues from others’ viewpoints in an open-minded manner), intellectual integrity (ability to consistently apply good standards of thinking), intellectual perseverance (willingness to overcome obstacles and adhere to rational principles despite irrational objections from others), faith in reason (belief that quality reasoning leads to quality outcomes), and fair-mindedness (treating all viewpoints equally without regard for one’s own feelings or vested interests). Based on other critical thinking sources, I might choose to also add introspection (routinely examining one’s own thought processes and seeking to overcome biases and errors introduced by human limitations) and possibly other traits such as inquisitiveness, flexibility, prudence, etc.

Last is the set of values/commitments. This is a small set with only one member: a commitment to the truth, or the true best answer, where by “best” I mean the most defensible choice based on the available evidence and reasoning.

At the highest level, the relationships {R} between the cognitive skills, characteristic habits, and values/commitments enable me to loosely assemble these components into a structural model of critical thinking as follows:

Values/commitments provide the foundation for critical thinking. It is the commitment to searching for the truth that motivates the need for intellectual humility, empathy, and the various other critical thinking traits, and these traits in turn regulate the way in which cognitive skills are applied to form opinions, make decisions, and solve problems.

One interesting thing about structuring the model this way is that the vertical axis roughly corresponds to intelligence. Elements towards the top of the model (i.e. cognitive skills) are those that are measured by conventional definitions of intelligence, i.e., IQ, and elements lower down decreasingly depend upon intelligence. As I’ve said before, critical thinking is much more than just IQ. A person’s “practical intelligence” — a person’s intelligence for all practical purposes in the real world, i.e., how well a person can come to the right opinions, make the best decisions, and formulate good solutions to problems in the real world, rather than their ability to solve logic puzzles on an IQ test — is determined more by their intellectual habits and attitudes (characteristic habits) than by their cognitive skills.

Another interesting thing about this model structure is that the same structure holds for types of thinking other than critical thinking. For example, the non-critical thinker may be more committed to his own ego than the truth, or more committed to a pet cause or a political ideology. This commitment in turn motivates that particular person to adopt habits such as closed-mindedness, intellectual arrogance, and so on. It is what populates this model structure that determines the type of thinker.

So, this is my initial model of critical thinking. It’s pretty austere, but I think it’s a good starting point to build on. In the future I might try to come up with a use for the horizontal axis and decompose each of the three sets (values/commitments, characteristic habits, and cognitive skills) to arrange them along that variable. The model is also only a structural model (showing components and their relationships), and does not show any dynamics or processes that occur during critical thinking; those would be nice additions too.