What is Critical Thinking?

Critical thinking is the art of analyzing and evaluating thinking with a view to improving it in order to make an informed decision that is most likely to result in desired effects.

Critical thinking describes a process of uncovering and checking our assumptions and reasoning. First, we analyze to discover the assumptions that guide our decisions, actions, and choices. Next, we check the accuracy of these assumptions by exploring as many different perspectives, viewpoints, and sources as possible. Finally, we make informed decisions or judgments that are based on these researched assumptions.

Life is a series of decisions, some small, some much larger. Whom we date or choose as friends, the work or career we pursue, which political candidates we support, what we choose to eat, where we live, what consumer goods we buy, if and whom we marry, if and how we raise children—all these decisions are based on assumptions. We assume our friends will be trustworthy and won't talk about us behind our backs. We assume our career choices will be personally fulfilling or financially remunerative. We assume politicians we vote for have our, or the community's, best interests at heart. We assume that the foods we choose to eat are healthy for us, and so on.

These assumptions are sometimes correct. At other times, however, the assumptions we base our decisions on have never been examined. Sometimes we hold these assumptions because people we respect (friends, parents, teachers, religious leaders) have told us they are right. At other times we have picked these assumptions up as we travel through life but can't say exactly where they've come from. To make good decisions in life we need to be sure that these assumptions are accurate and valid – that they fit the situations and decisions we are facing. Critical thinking describes the process we use to uncover and check our assumptions. Decisions based on critical thinking are more likely to be ones we feel confident about and to have the effects we want them to have.

Your Mental Models

Mental models are the filters we use to understand the world. A mental model is a representation of how something works. Everyday we encounter so much information that we cannot store it all and the phenomena we encounter are too complex to understand every detail. Therefore, we use filtering models to simplify the complex into organizable and understandable chunks, conceptual models to file and organize new information, and reasoning models to create new ideas and make decisions.

Mental models shape what we think, how we interpret what we value most, where we direct our attention, how we reason, and where we perceive opportunities. The quality of our thinking is only as good as the models in our head and their usefulness in a given situation. The best models improve our likelihood of making the best decisions. By critically examining our assumptions, we can adjust them to be in better accord with reality and they become more powerful mental models in the toolkit through which we understand reality.

All of us go through life with many incorrect core assumptions about reality. For example, most of us believe (1) we are perceiving reality accurately, (2) our perceptions are valid, and (3) that what is obvious to us must be obvious to others. Let that sink in for a minute: these are incorrect assumptions. It is simply not possible to perceive reality accurately and everyone's reality is different. Our sensory nervous system sends gigabytes per minute of data to the brain but the brain has the attentional bandwidth to process megabytes per minute. On top of that, we are always allocating some of our bandwidth to our thoughts (have you every been lost in thought and missed an important detail?). To improve our thinking, first we have to accept that our perceptions of the moment are filtered through mental models, that our most dearly held beliefs may not correctly describe reality, and be open to improving them.

Building your toolkit of mental models is a lifelong project. Stick with it, and you'll find that your ability to understand reality, accomplish your goals, deepen your relationships, and make the best decisions will always improve. Critical thinking is a set of reasoning tools that we use to improve our other models about the world. They are the foundation upon which we can build our best mental models. In the next section, you will find an overview of the reasoning tools described in this website.

Organization of this Resource

Learn to analyze the elements of reasoning

The Critical Analysis page is dedicated to the first step in the process of developing critical thinking skills, recognizing elements of reasoning that are present in the mind whenever we reason. I categorize six elements of reasoning: purposes, questions, points of view, information, assumptions, and reasoning. Note how these elements are related in the following paragraph.

To take command of our thinking, first we need to clearly formulate both our purpose and the question at issue. To uncover truths, we need to make logical inferences based on sound assumptions and information that is both accurate and relevant to the question we are dealing with. We need to understand our own point of view and fully consider other relevant viewpoints. We also need to recognize problems created by bugs in the human operating system by formally working around them. These bugs can be categorized into two major categories, each of which has it's own page.

Fallacies of reasoning are found in unsound arguments that may sound persuasive on the surface.

Cognitive biases are a predictably systematic patterns of deviation rationality in judgment. Cognitive biases can lead to irrational thought through distortions of perceived reality, inaccurate judgment, or illogical interpretation. For example, confirmation bias is the tendency to interpret new evidence as confirmation of one's existing beliefs and filter-out information that does not confirm one's existing beliefs.

Learn to evaluate reasoning

The Critical Evaluation page describes the second step in the process of critical thinking, evaluating the quality of thought. We need to use concepts justifiably and follow out the implications of decisions we are considering.

Learn to avoid other common mistakes

No one is a master of every discipline, however there are some common misconceptions that people have of other disciplines that you should learn to avoid.

Additionally, I have created a page of common writing errors that I have observed in developing student writing.

Before submitting your writing, I suggest that you please consult these resources as checklists and verify that you have done your best to avoid these mistakes.