According to Donald Ary, Lucy Cheser Jacobs and Christine K. Sorensen, the major sources of knowledge can be categorized under five headings: (1) experience, (2) authority, (3) deductive reasoning, (4) inductive reasoning, and (5) the scientific approach.
(1) EXPERIENCE
Experience is a familiar and well-used source of knowledge.
By personal experience, you can find the answers to many of the questions you face. Much wisdom passed from generation to generation is the result of experience. If people were not able to profit from experience, progress would be severely retarded. In fact, this ability to learn from experience is a prime characteristic of intelligent behavior.
Experience has limitations as a source of knowledge. How you are affected by an event depends on who you are. Two people will have very different experiences in the same situation. The same forest that is a delightful sanctuary to one person may be a menacing wilderness to another. Two supervisors observing the same classroom at the same time could truthfully compile very different reports if one focused on and reported the things that went right and the other focused on and reported the things that went wrong.
Another shortcoming of experience is that you so frequently need to know things that you as an individual cannot learn by experience.
(2) AUTHORITY
For things difficult or impossible to know by personal experience, people frequently turn to an authority; that is, they seek knowledge from someone who has had experience with the problem or has some other source of expertise. People accept as truth the word of recognized authorities.
We go to a physician with health questions or to a stockbroker with questions about investments. A student can look up the accepted pronunciation of a word in a dictionary. A beginning teacher asks an experienced one for suggestions and may try a certain technique for teaching reading because the teacher with experience suggests that it is effective.
Although authority is a very useful source of knowledge, you must always ask, How does authority know? In earlier days, people assumed an authority was correct simply because of the position he or she held, such as king, chief, or high priest. Today, people are reluctant to rely on an individual as an authority merely because of position or rank. They are inclined to accept the assertions of an authority only when that authority is indeed a recognized expert in the area.
Closely related to authority are custom and tradition, on which people depend for answers to many questions related to professional as well as everyday problems. In other words, people often ask, “How has this been done in the past?” and then use the answer as a guide for action. Custom and tradition have been prominent infl uences in the school setting, where educators often rely on past practices as a dependable guide. However, an examination of the history of education reveals that many traditions that prevailed for years were later found to be erroneous and had to be rejected. For generations, it was considered good practice to humiliate students who made mistakes with dunce caps and the like. It is wise to appraise custom and tradition carefully before you accept them as reliable sources.
Authority is a quick and easy source of knowledge. However, as a source of knowledge, authority has shortcomings that you must consider. First, authorities can be wrong. People often claim to be experts in a field when they do not really have the knowledge to back up the claim. Second, you may find that authorities disagree among themselves on issues, indicating that their authoritative statements are often more personal opinion than fact.
(3)DEDUCTIVE REASONING
Ancient Greek philosophers made perhaps the first significant contribution to the development of a systematic approach for gaining knowledge. Aristotle and his followers introduced the use of deductive reasoning, which can be described as a thinking process in which one proceeds from general to specific knowledge through logical argument. An argument consists of a number of statements standing in relation to one another. The final statement is the conclusion, and the rest, called premises, offer supporting evidence. A major kind of deductive reasoning is the syllogism. A syllogism consists of a major premise and a minor premise followed by a conclusion.
For example, “All men are mortal” (major premise); “The king is a man” (minor premise); “Therefore, the king is mortal” (conclusion). In deductive reasoning, if the premises are true, the conclusion is necessarily true. Deductive reasoning lets you organize premises into patterns that provide conclusive evidence for a conclusion’s validity. Mystery fans will recall that Sherlock Holmes frequently would say, “I deduce . . .” as he combined previously unconnected facts in such a way as to imply a previously unsuspected conclusion.
Deductive reasoning has its limitations. To arrive at true conclusions, you must begin with true premises. The conclusion of a syllogism can never exceed the content of the premises. Because deductive conclusions are necessarily elaborations on previously existing knowledge, you cannot conduct scientific inquiry through deductive reasoning alone because it is difficult to establish the universal truth of many statements dealing with scientific phenomena. Deductive reasoning can organize what people already know and can point out new relationships as you proceed from the general to the specified, but it is not sufficient as useful in research because it provides a way to link theory and observation. It lets researchers deduce from existing theory what phenomena they should observe. Deductions from theory can help build hypotheses, which are a vital part of scientific inquiry.
(4) INDUCTIVE REASONING
As noted previously, the conclusions of deductive reasoning are true only if the premises on which they are based are true. But how are you to know if the premises are true?
You can see the difference between deductive and inductive reasoning in the following examples:
Deductive: Every mammal has lungs.
All rabbits are mammals.
Therefore, every rabbit has lungs.
Inductive: Every rabbit that has ever been observed has lungs.
Therefore, every rabbit has lungs.
Note that in deductive reasoning you must know the premises before you can reach a conclusion, but in inductive reasoning you reach a conclusion by observing examples and generalizing from the examples to the whole class or category. To be absolutely certain of an inductive conclusion, the investigator must observe all examples. This is known as perfect induction under the Baconian system; it requires that the investigator examine every example of a phenomenon. In the preceding example, to be absolutely sure that every rabbit has lungs, the investigator would have to have observations on all rabbits currently alive, as well as all past and future rabbits. Clearly, this is not feasible; you generally must rely on imperfect induction based on incomplete observation.
(5) THE SCIENTIFIC APPROACH
Exclusive use of induction often resulted in the accumulation of isolated knowledge and information that made little contribution to the advancement of knowledge. Furthermore, people found that many problems could not be solved by induction alone. In the 19th century, scholars began to integrate the most important aspects of the inductive and deductive methods into a new technique, namely the inductive – deductive method, or the scientific approach. This approach differs from inductive reasoning in that it uses hypotheses. A hypothesis is a statement describing relationships among variables that is tentatively assumed to be true. It identifies observations to be made to investigate a question.
Darwin’s procedure, involving only observation, was unproductive until reading and further thought led him to formulate a tentative hypothesis to explain the facts that he had gathered through observation. He then proceeded to test this hypothesis by making deductions from it and gathering additional data to determine whether these data would support the hypothesis. From this method of inquiry, Darwin was able to develop his theory of evolution. This use of both inductive and deductive reasoning is characteristic of modern scientific inquiry.
The scientific approach is generally described as a method of acquiring knowledge in which investigators move inductively from their observations to hypotheses and then deductively from the hypotheses to the logical implications of the hypotheses. They deduce the consequences that would follow if a hypothesized relationship were valid. If the deduced implications are compatible with the organized body of accepted knowledge, researchers then further test them by gathering empirical data. On the basis of the evidence, they accept or reject the hypotheses.
The use of hypotheses is the principal difference between the scientific approach and inductive reasoning. Innductive reasoning, you make observations first and then organize the information gained. In the scientific approach, you reason what you would find if a hypothesis were true and then you make systematic observations to confirm (or fail to confirm) the hypothesis.
[Adapted from Donald Ary, Lucy Cheser Jacobs and Christine K. Sorensen (Introduction to Research in Education, 8th Edition, Wadsworth, Cengage Learning, 2010, pp. 2 – 12)]
