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God has given us. The other proceeds from data which we know to be uncertain, and the uncertainty of which we are able to appreciate. They, of course, lead to an entirely different subjective result, and a line of distinct demarcation must ever separate the one from the other.

II. Reasoning from induction.

The object of this mode of reasoning is to establish a general law, from the observation of particular instances. The principle on which it depends has been already explained, when treating of cause and effect. See pages 153 -158.

We

It is in conformity with our intuitive beliefs, that, from observing a change, we proceed to ascertain its cause. We know that, wherever the cause exists, the effect must necessarily follow, and that wherever an event always follows a given antecedent, this antecedent must be the cause. therefore observe all the various phenomena which precede a change. We ascertain, so far as possible, which of them is the invariable antecedent; in other words, that which being present the effect exists, and which being removed the effect ceases. When this has been done, we consider ourselves to have ascertained the cause."

Having thus determined, by experiment, the cause in this particular case, we proceed as follows:

What is the cause of this effect in one case must be the cause in all cases.

The event A is the cause in this case; therefore,

The event A is the cause in all cases.

It frequently happens that there are several antecedents, and the greatest skill and the most persevering sagacity are requisite in order to determine which of them is invariable. We are obliged to try every variety of combinations, in order to ascertain with perfect precision the cause, and to sever it from every occasional and variable antecedent. When,

however, this is done, we generalize with entire confidence, and consider the law as established.

The manner in which we proceed, in such a case, is illustrated most happily in the process employed by Sir Isaac Newton to discover the cause of the solar spectrum. The full account may be found in the third chapter of Sir David Brewster's life of this great philosopher.

III. Of reasoning from analogy.

In this form of reasoning, we do not attempt to prove a proposition true, and we may not even attempt to prove it probable. All that we generally desire is to prove it not improbable.

In the other cases of which we have treated, we proceed upon the supposition that the same cause, under the same conditions, will produce the same effects. Here we proceed upon the supposition, not that the same cause will produce the same effect, but merely that similar causes may produce similar effects, in the absence of evidence to the contrary.

If this mode of reasoning were reduced to a syllogism it would take substantially the following form:

1. Similar causes may produce similar effects.

2. The cause A is similar to the cause B;

3. Therefore the cause A and B may produce similar effects.

The principal uses of analogical reasoning are the following:

1. It is frequently employed with success in answering an a priori objection. It is thus used with great acuteness and unanswerable force, by Bishop Butler, in his Analogy. Thus, if men deny the existence of God, and hence infer that there can be no future state of rewards and punishments, his answer is as follows: It is granted, even by atheists themselves, that in the present state we are rewarded for some actions and punished for others; that is, that we

find ourselves under a moral government. But, if we exist under such conditions now, when, by the supposition, there is no God, there can be no reason assigned why we may not continue to exist after death, and exist under the same conditions as at present; that is, under a moral government, in which we shall be rewarded and punished according to the character of our actions. The whole of this admirable treatise, one of the most remarkable that any language can produce, is intended to show that the principles of moral government taught in the Scriptures are strictly analogous to those everywhere exhibited in the government of the world, as seen by natural religion. Hence, it is evident that if God has adopted these principles for our government in one case, there can be no a priori reason why he should not adopt them in another case. "It will here be found," says he, "not taken for granted, but proved, that any reasonable man, who will thoroughly consider the matter, may be as much assured as he is of his own being, that it is not so clear a case that there is nothing in it."

While, however, analogy claims to do no more than this, it, in many cases, in fact, does much more. It is evident that the greater the similarity of cause the greater is the probability of the similarity of effects. It may thus, in some cases, approximate to proof; at the least, it furnishes grounds for a decided opinion. Thus, the similarity of many of the effects of electricity and galvanism created the opinion that they were the same agent, before their identity was discovered.

2. It will readily appear that an important use of analogy is to aid us in scientific investigation. Suppose, for instance, that we have discovered the cause for a well-known effect. We observe another effect of a similar character, and we instinctively are led to inquire, may it not arise from the same or a similar cause? Hence, in our search after

causes, we are greatly aided, and much useless labor is saved, by such an indication. Thus, Sir H. Davy discovered the metallic basis of potash. But there are other alkalies in many of their sensible properties nearly allied to potash. How natural was it for him to expect that the same laws governed them all, and that they all were formed in the same manner from metallic bases!

3. Analogy is frequently used by the orator with great effect. Thus, if it is admitted that a man has acted in one way at one time, there is no reason why he might not be expected to act in the same way at another time. Or, if it is honorable for one man to act in a particular manner in one case, there can be no reason why it is not honorable for another man, in a case essentially alike, to act in a similar manner. This mode of reasoning is used with the happiest success by Erskine, in the introduction of his argument for Stockdale. He commences by alluding to the fact that, though connected by ties of the closest intimacy with the political party who had directed the prosecution, yet, Mr. Stockdale had not hesitated to entrust him with his defence. He adds, "This, however, is a matter of daily occurrence. lied is the character of the English bar, that no political bias ever interferes with the discharge of the duty of an advocate; that, whatever may be our public principles, or the private habits of our lives, they never cast even a shade across the path of our professional duties. If this be characteristic of the bar of an English court of justice, what sacred impartiality may not every man expect from its jurors and its bench." Many similar instances may be found in the speeches of this eminent orator, perhaps the most consummate advocate of modern times.

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It is, however, obvious, that this mode of reasoning is liable to great abuse. The whole force of the argument depends on the similarity of the cases. But if an advocate

can present cases seeming to be similar, while, in fact, they are widely diverse, he may draw from them the most erroneous conclusions. It is, therefore, the business of an opponent, or of an inquirer after truth, to examine reasoning of this kind with the closest scrutiny; and, when it is defective, point out the dissimilarity of the cases, and show the result to which such analogies would lead, if we allowed them to form the foundation of our judgment.

REFERENCES.

Probable evidence - Stewart, vol. ii., chap. 2, sec. 4; Locke, Book 4, chap. 15; Abercrombie, Part 2, sec. 3.

Induction - Reid, chap. 6, sec. 24; Stewart, vol. ii., chap. 4, sec. 1; Cousin, chap. 9.

Analogy-Reid's Inquiry, Essay 1, chap. 4; Stewart, vol. ii., chap. 2, sec. 4, chap. 4, sec. 4; Locke, Book 5, chap. 16, sec. 12; Abercrombie, Part 3, sec. 4.

SECTION V. -ON THE IMPROVEMENT OF THE REASONING POWERS.

It is appropriate to close this chapter with a few suggestions on the manner of improving the reasoning powers.

If the remarks in the preceding pages are correct, it will appear that the process which we employ in reasoning is, in all cases, essentially the same. Our object is to show such a relation between the known and the unknown, that, if one be true, the other is equally true; or, if one be only probable, the other is equally probable. If our premises are denied, we proceed to show their relation to something better known and more universally admitted, and thus fall back, step by step, until we rest upon those elementary truths which are given us in the constitution of the human

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