Logic And Critical Thinking

Truth is the object of thinking. Some truths are obvious; others are difficult to acquire. Some judgments we make are simple; some judgments are complicated. Some arguments, whether made by us or others, may be straightforward and easily understood; other arguments may be complex and consist of a series of smaller arguments, each needing to be critically examined and evaluated.

Almost every object of knowledge has a branch of knowledge which studies it. Planets, stars, and galaxies are studied by astronomy. Chemistry studies the structure, composition, and properties of material substances and the transformations they undergo. The origin, evolution, and development of human society is the object studied by sociology. Economics, biology, geography, and grammar all have objects of knowledge which they investigate, describe, and try to explain.

Critical thinking involves a knowledge of the science of logic, including the skills of logical analysis, correct reasoning, and understanding statistical methods. Critical thinking, however, involves more than just an understanding of logical procedures. A good critical thinker must also understand the sources of knowledge, the nature of knowledge, and the nature of truth. But first, what is the science of logic?

The object of knowledge involved in the science of logic is "thinking," but it is "thinking" approached in a special way. Generally speaking, logic is that branch of knowledge which reflects upon the nature of "thinking" itself. But this may confuse logic with other branches of knowledge which also have the nature of "thinking" as a part of their specific object of investigation. We need a more detailed and accurate definition to eliminate any confusion.

Logic doesn't just deal with "thinking" in general. Logic deals with "correct thinking." Training in logic should enable us to develop the skills necessary to think correctly, that is, logically. A very simple definition would be: Logic is the subject which teaches you the rules for correct and proper reasoning. For those of you who want a more complete and "sophisticated" definition of logic, you can define it this way: Logic is the science of those principles, laws, and methods, which the mind of man in its thinking must follow for the accurate and secure attainment of truth. Take your choice.

Natural Logic and Scientific Logic

We need to be aware of a distinction between what some call "natural logic" or common sense and "scientific" logic. We all have an internal sense of what is logical and what is not, which we generally refer to as "common sense." This "natural" logic we have learned from the moment of birth, through our personal experiences in the world and through our acquisition of language. Scientific logic, on the other hand, is simply our natural logic trained and developed to expertness by means of well-established knowledge of the principles, laws, and methods which underlie the various operations of the mind in the pursuit of and attainment of truth.

We have referred to the "science" of logic but logic is really more than just a science. The science part is the knowledge of the principles, laws, and methods of logic itself. This is important, to be sure. But logic must be put into action or else the knowledge provided within the science of logic is of little use. We can, therefore, also speak of the "art" of logic, that is, the practical application of the science of logic to our everyday affairs. Logic is not intended merely to inform or instruct. It is also directive and aims at assisting us in the proper use of our power of reasoning. In this sense, we can speak of logic as both a science and an art, a practical art meant to be applied in our ordinary affairs.

Logic and Psychology

We want to be sure that we don't confuse the science of logic with the science of psychology. Psychology also studies "thinking," but it is a separate, autonomous discipline of its own. And logic is not a branch of psychology, but a separate discipline of its own. How are logic and psychology different?

The most obvious difference is that psychology is a "descriptive" science while logic is a "prescriptive" science. The difference between a descriptive science and a prescriptive science can best be illustrated by an example.

Let's suppose we are scientists and have been asked to study the differences between the American form of government and the British form of government. We find that in the United States there are three separate branches in the central government: the executive branch which includes the president, the legislative branch which includes the Senate and the House of Representatives, and the judicial branch which includes the Supreme Court. We discover that the president is elected by vote of the people, as are the senators and representatives, and that the judges of the Supreme Court are appointed by the president with approval of the Senate. Furthermore, we find that the president is both the ceremonial leader and the chief executive of the nation.

Now we turn our attention to England. We see that the Queen of England is not elected and functions primarily as the ceremonial leader of the country. Instead of an elected Congress, England has a parliament system, consisting of a House of Commons, which is elected, and a House of Lords, which is not elected by the people. Furthermore, we find out that the prime minister, who is the real head of the government, is not elected by the people, but is elected by the leading political party in the House of Commons.

What we have done in the above example is simply "describe" and report on each form of government, noting any similarities and differences between them. We have been functioning as "descriptive" scientists, in this case, as political scientists since governments are an object of knowledge of a scientific discipline called political science.

Let's suppose now that we go on to argue that England should adopt the form of government we have in the United States. In this case, we are no longer describing or reporting on a state of affairs. We are now recommending or "prescribing" how England should conduct its affairs when it comes to government. We have ceased to be scientists at this point and have become political philosophers. We are no longer being "descriptive," we have become "prescriptive."

Psychology is also a descriptive science. It is not primarily interested in how