Critical Thinking is a broad church. As an academic program, it draws from a wide range of disciplines including psychology, philosophy, and logic. All these areas are important - descriptive psychology gives us insight into our cognitive biases and heuristics, philosophy helps us understand the nature of truth and helps to understand what it means to be rational, and logic provides the tools for making valid inferences.
Yet amongst them, one area stands out as especially critical - argumentation.
When people hear the word argument, they often think of conflict. Within the thinking domains however, an argument is simply a connected series of statements used to establish definite proposition.
Argumentation then, is the study of how beliefs are justified via appropriate reasoning. It's a theory of rational persuasion whereby we can accept certain claims as true if they are backed by a cogent argument.
To understand why argumentation is so essential to critical thinking, we need to consider why we value critical thinking in the first place. A key objective in the application of critical thinking is to help ensure that our beliefs are warranted or justified. In other words, to ensure that our beliefs match reality or, in the absence of any way to confirm what the truth is, to stand confidently based on the quality of our reasoning.
The account of what exactly justifies or warrants our beliefs comes from epistemology - the branch of philosophy that studies the nature of knowledge. So a useful way of thinking about critical thinking is as a form of applied epistemology.
Epistemology is a normative endeavour. This means it is concerned with how we should think, as opposed to a descriptive one like psychology which studies how we actually do think. It is epistemology that gives us the standards of rational inference, of testimony, and of evidence - the standards we need to answer questions like "how do I know this is true?" or "which theory is the most plausible?".
This normative component is essential because without it, we have no way of reconciling completing claims about what is or might be true. Without it, all we can do is contradict each other when we disagree.
And it's in reconciling of disagreement that we can start to see argumentation connect the dots between the different subjects that inform critical thinking. Argumentation links the normative aspect of epistemology with the social aspect of persuasion. It gives us the tools to persuade others (and be persuaded ourselves) based on cogent reasoning rather than the tone, tempo, or volume of the person making the claim.
Argumentation is what makes social cognition so effective.
Given all this, it becomes clear that the effectiveness of any program that aims to promote critical thinking will be severely limited if it doesn't explicitly focus on student cognition and the norms of good reasoning.
If improving the ability of your students to think critically is important, then it's essential to think and plan in the language of student cognition.