ing him, for disabling him from making any further resistance in support of his injustice, and the most effectual, the most proper methods may be chosen, provided they have nothing odious, be not unlawful in themselves, or exploded by the law of nature.' Here let me pause for

a moment and ask whether it be odious in itself or exploded by the law of nature to seize those debts?

The "authority authority" used for the purposes of such expert evidence as this must bear two special tests: (a) Is the witness possessed of the knowledge necessary to justify his acceptance as an expert in the matter in question? (b) Is his authority recognized by the audience? However great the knowledge or skill of an expert, if his greatness is unknown to the hearer or reader, the effect of quoting him will be a mere flash in the pan." The audience or reader will see in the pretended "authority" nothing more than a meaningless name, and so will ignore his statement. The disputant must always be sure that the worth of his expert is accepted; and if there may be any doubt, his first duty is to establish for him a satisfactory reputation.

To summarize:

I. Proof is composed of (A) evidence and (B) argu

ments.

A. Proof is the name used to designate all the means which serve to convince the mind

G

of the truth or falsity of any fact or proposition.

1 "Great Speeches by Great Lawyers," p. 13.

B. Evidence consists of all the matters of fact that may be used in the generating of

proof.

C. An argument is the process by which from knowing one fact or a certain number of

facts we infer the existence of other facts.

II. Evidence may be divided into:

A. Direct evidence and indirect or circumstan

tial evidence.

B. Written évidence and unwritten evidence.

III. The tests of evidence.

A. Tests of the nature of the evidence itself.
1. The burden of proof rests on the person
who originally asserts the existence of
the fact.

2. Evidence should be consistent with hu-
man nature and human experience.

3. Evidence should be derived from witnesses who can testify to the fact from their own personal knowledge.

4. Evidence should be consistent with all the known facts of the case.

5. Certain kinds of evidence are especially valuable.

a. Admissions and declarations against

interest.

b. Undesigned evidence.

B. Tests of the sources of evidence.

1. There are two kinds of evidence clas

sified with respect to their sources:

a. Ordinary evidence.

b. Expert evidence.

2. Tests of the sources of ordinary evidence.

a. Physical powers of witnesses.

b. Mental powers of witnesses.
(1) Memory.

(2) Accuracy of statement.

c. Opportunity for observation of the facts.

d. Veracity of witnesses.

(1) Exaggeration.

(2) Deliberate perversion of the truth

is due to:

(a) Interest in the outcome of the controversy.

(b) Defective moral character.

3. Tests of sources of expert evidence. a. Is the witness possessed of the special knowledge necessary to justify his acceptance as an expert?

b. Is his authority recognized by the audience or reader?

CHAPTER III

KINDS OF ARGUMENTS

THERE is a distinct difference in purpose and method between argumentation and formal logic. It is near the truth to say that formal logic is the science of which argumentation is the corresponding art. Logic aims merely to investigate and explain "the operations and processes of thought." "Its first business must be to investigate the nature of thought," as it is actually carried on in the human mind; but it makes no attempt to prescribe any practical rules for correct thinking. Argumentation, on the other hand, finds only a secondary interest in scientific logic, its purpose being to make practical rules and suggestions which will facilitate correct reasoning and the producing of beliefs in the minds of others.

This difference is strongly marked in the methods employed by each in the treatment of the kinds of arguments, or, as the term is in logic, of "inferences." Logic explains the different ways in which the mind may work in making an inference or reasoning. In argumentation the purpose in discussing the methods of inference, or "the kinds of arguments," is to make clear the rules that must be

followed in order to make arguments that will be valu. able for the purpose of convincing and persuading others. For this purpose the necessity of knowing the various kinds of arguments that may be used is twofold: it is necessary (1) in order to be able to select the arguments that will be valuable in constructing one's own proof, and (2) in order to be able to attack the proofs of an opponent.

Since these are our only two purposes, little attention need be given to the questions of what kinds of arguments are most naturally used, or in what forms these arguments are generally stated or explained. For example, the causal connection in many arguments is often not understood by the person making the argument, and hence inferences from cause to effect or from effect to cause may seem to be comparatively few in number. Again, in many instances where the causal connection is understood, it is not explained in the statement of the proof. But these facts are not of any real significance for our purposes. In order to be able to select good arguments for our own use, and in order to be able to attack the weak arguments of others, however others may understand them and however they may be stated, we must know what it is in the arguments that makes them strong or weak.

Nearly all writers on the subject of rhetoric have divided the kinds of arguments into three classes, and have given to these classes the names, antecedent probability, sign, and example. The mean