4. Novel reading is a waste of time.
5. Tramps ought not to be fed.
(Make a brief. Consider the arrangement of your arguments. Read Section 72.)
+176. Errors of Induction.+—A common error is that of too hasty generalization. We conclude that something is always so because it happened to be so in the few cases that have come under our observation. A broader experience frequently shows that the hastily made generalization will not hold.
Some people are led to lose faith in all humanity because one or two of their acquaintances have shown themselves unworthy of their trust. Others are ready to pronounce a merchant dishonest because some article purchased at his store has not proved to be so good as it was expected to be. There are those who are superstitious concerning the wearing of opals, claiming that these jewels bring the wearer ill luck, because they have heard of some instances where misfortune seemed to follow the wearing of that particular stone. What may seem to be causes and effects at first may, upon further investigation or inquiry, prove to be merely chance coincidences. In your work in argument, whether for the class room or outside, be careful about this point. Remember that your induction will be weak or even worthless if you draw conclusions from too few examples.
Often one example seems sufficient to cause belief. We might believe that all giraffes have long necks, even though we had seen but one; but such a belief would exist because, by many examples of other animals, we have learned that a single specimen will fairly represent all other specimens of the same class. On the other hand, if this one giraffe should possess one brown eye and one white eye, we should not expect all other giraffes to have such eyes, for our observation of many hundreds of animals teaches us that the eyes of an animal are usually alike in color. In order to establish a true generalization, the essential characteristics must be selected, and these cannot be determined by rule, but rather by common sense.
+177. Deductive Reasoning.+—When once a general principle has been established, we may demonstrate the truth of a specific proposition by showing that the general principle applies to it. We see a gold ring and say, "This ring is valuable," because we believe the general proposition, "All articles made of gold are valuable." Expressed in full, the process of reasoning would be—
A. All articles made of gold are valuable. B. This ring is made of gold. C. Therefore this ring is valuable.
A series of statements such as the above is called a syllogism. It consists of a major premise (A), a minor premise (B), and a conclusion (C).
Of course we shall not be called upon to prove so simple a proposition as the one given, but with more difficult ones the method of reasoning is the same. The process which applies a general proposition (A) to a specific instance (C), is called deductive reasoning.