Skip to main content

Critical Thinking

Critical thinking basically means not accepting ideas presented to us at their face value. The knowledge we get out of being educated will be nothing more than indoctrination if we cannot use it to think for ourselves. We all do have some ability to think critically. If you watched the movie Transformers and wondered where the metal came from when a little passenger car turned into a giant robot, you are thinking critically. Critical thinking is the essential skill we use when we analyze an argument or compose an analytical paper. Our natural capacity to think critically, however, is no match for such a complex task. We could dig with our bare hands, but to dig deep, we need a shovel. Likewise, to think critically deeply, we need conceptual tools. This is why many colleges offer courses entitled Critical Thinking or Scientific Reasoning. These courses tend to be interdisciplinary to encompass various disjoint topics and can be quite technical. This book will help you improve your critical thinking in a fun and easy way.

In this book, you learn three platinum skills for critical thinking: logical reasoning, fallacy detection, and scientific reasoning. Logical reasoning is about the entailment relationship among ideas. That is, what we can infer to be true from what we already know to be true. An entailment relationship can either be truth-preserving or ampliative. An inference is truth-preserving if the truth of the conclusion is already embedded in the truth of its premises, and it is ampliative (or inductive), otherwise. Deductive logic is a paragon of truth-preserving inference, and statistical inference methods, like the Bayesian method that utilizes prior probabilities and the hypothesis testing method that utilizes error probabilities, are exemplary cases of inductive logic. As these are vast fields of their own, in this book, we just focus on the most important concept in deductive logic, validity. Through validity, we know why good reasoning is good.

Studying good reasoning is insufficient for critical thinking, however. Logic can tell us why good reasoning is good, but it cannot tell us why bad reasoning is bad. Logic is blind to the content of the argument, which is why a logically correct argument can be bad. Thus needed is the study of fallacies, defective arguments. A problem with the study of fallacies is that it will always be incomplete because manners of incorrect reasoning can be infinite in principle. In fact, the famous Alan Turing proved that, while we can algorithmically list all the valid arguments, it is algorithmically impossible to generate all the invalid arguments one after another. To study fallacies systematically, we learn them under the following six types: formal fallacies, irrelevance, weak induction, illicit presumption, ad hoc-ness, and abuse and misuse of language.

The third skill is scientific reasoning. We live in the era where science has become the religion. The public blindly assumes that scientists are lonely servants of truth, patient observers, and honest recorders. This image of scientists is far from the reality as the field of science is a career system for scientists. Revering the Principle of Publish or Perish, scientists will do anything to publish: they scratch each other’s back and massage the data. This favoritism and adhocism in science has led to the replication crisis that most published research findings are false since they cannot be replicated in subsequent investigation. The irresponsible behaviours of scientists produced junk science in the public sphere. All this implies that the public is also responsible for learning about scientific reasoning. In this book, following the field of experimental design, we study scientific reasoning under the headings of observational validity, construct validity, internal validity, and external validity.