EXERCISES
A. Use the following terms in expressed propositions:—
1. Immigration. 2. Elevated railways. 3. American history. 4. Military training. 5. Single session. 6. Athletics.
B. Explain the following propositions:—
1. The United States should adopt a free-trade policy. 2. Is vivisection justifiable? 3. The author has greater influence than the orator. 4. The civil service system should be abolished. 5. The best is always cheapest.
C. Can you restate the following propositions so that the meaning of each will be made more definite?
1. Athletics should be abolished. (Should all athletic exercises be
abolished?)
2. Latin is better than algebra. (Better for what purpose? Better for
whom?)
3. Training in domestic arts and sciences should be provided for high school pupils. (Define domestic arts and sciences. Should they be taught to all high school pupils?)
4. Punctuality is more important than efficiency.
5. The commercial course is better than the classical course.
6. A city should control the transportation facilities within its limits.
+Theme XCVI.+—Write out an argument favoring one of the propositions as restated in Exercise C above.
(Before writing, make a brief as indicated in Section 77. Consider the arrangement of your argument.)
+173. Clear Thinking Essential to Argument.+—Having clearly in mind the proposition which we wish to prove, we next proceed to give arguments in its support. The very fact that we argue at all assumes that there are two sides to the question. If we hope to have another accept our view we must present good reasons. We cannot convince another that a proposition is true unless we can tell him why it is true; and certainly we cannot tell him why until we know definitely our own reasons for believing the statement. In order to present a good argument we must be clear logical thinkers ourselves; that is, we must be able to state definite reasons for our beliefs and to draw the correct conclusions.
+174. Inductive Reasoning.+—One of the best preparations for trying to convince others is for us to consider carefully our own reasons for believing as we do. Minds act in a similar manner, and what leads you and me to believe certain truths will be likely to cause others to believe them also. A brief consideration of how our belief in the truth of a proposition has been established will indicate the way in which we should present our material in order to cause others to believe the same proposition. If you ask yourself the question, What leads me to believe as I do? the answer will undoubtedly be effective in convincing others.
Are the following propositions true or false? Why do you believe or refuse to believe each?
1. Maple trees shed their leaves in winter.
2. Dogs bark.
3. Kettles are made of iron.
4. Grasshoppers jump.
5. Giraffes have long necks.
6. Raccoons sleep in the daytime.
7. The sun will rise to-morrow.
8. Examinations are not fair tests of a pupil's knowledge.
9. Honest people are respected.
10. Water freezes at 32° Fahrenheit.
11. Boys get higher standings in mathematics than girls do.
It is at once evident that we believe a proposition such as one of these, because we have known of many examples. If we reject any of the propositions it is because we know of exceptions (we have seen kettles not made of iron), or because we do not know of instances (we may never have seen a raccoon, and so not know what he does in the daytime). The greater the number of cases which have occurred without presenting an exception, the stronger our belief in the truth of the proposition (we expect the sun to rise because it has never failed).
The process by which, from many individual cases, we establish the truth of a proposition is called +inductive reasoning+.
+175. Establishing a General Theory.+—A general theory is established by showing that for all known particular cases it will offer an acceptable explanation. By investigation or experiment we note that a certain fact is true in one particular instance, and, after a large number of individual cases have been noted, and the same fact found to be true in each, we assume that such is true of all like cases, and a general law is established. This is the natural scientific method and is constantly being made use of in pursuing scientific studies. By experiment, it was found that one particular kind of acid turned blue litmus red. This, of course, was not sufficient proof to establish a general law, but when, upon further investigation, it was found to be true of all known acids, scientists felt justified in stating the general law that acids turn blue litmus red.
In establishing a new theory in science it is necessary to bring forward many facts which seem to establish it, and the argument will consist in pointing out these facts. Frequently the general principle is assumed to be true, and the argument then consists in showing that it will apply to and account for all the facts of a given kind. Theories which have been for a time believed have, as the world progressed in learning, been found unable to account for all of a given class of conditions. They have been replaced, therefore, by other theories, just as the Copernican theory of astronomy has displaced the Ptolemaic theory.
Our belief may be based upon the absence of facts proving the contrary as well as upon the presence of facts proving the proposition. If A has never told an untruth, that fact is an argument in favor of his truthfulness on the present occasion. A man who has never been dishonest may point to this as an argument in favor of placing him in a position of trust. Often the strongest evidence that we can offer in favor of a proposition is the absence of any fact that would support the negative conclusion.
The point of the whole matter is that from the observation of a large number of cases, we may establish the probable truth of a proposition, but emphasis needs to be laid upon the probability. We cannot be sure. Not all crows are black, though you may never have seen a white one. The sun may not rise to-morrow, though it has never failed up to this time. Still it is by this observation of many individual cases that the truth of the propositions that men do believe has been established. We realize that our inductions are often imperfect, but the general truths so established will be found to underlie every process of reasoning, and will be either directly or indirectly the basis upon which we build up all argument.
We may then redefine inductive reasoning as the process by which from many individual cases we establish the probable truth of a general proposition.