From the preceding, it is apparent that refutation consists of discrediting evidence and attacking reasoning. The ways to overthrow evidence will be considered first.
EVIDENCE.
It is taken for granted that the evidence mustered by the opponent is sufficient, if not overthrown, to establish his side of the discussion. Of course, if enough evidence for this purpose is lacking, one has only to call attention to this fundamental weakness in order to overthrow the argument then and there. The rules, therefore, for testing evidence assume that the opponent has cited facts that, if not combated, will establish his case.
These tests are the same as those given in Chapter VI; a hasty review of them, however, may be serviceable at this point.
I. Tests of the sources of evidence.
A. Is the witness competent to give a trustworthy account of the matter?
B. Is the witness willing to give an accurate account?
1. Does he have any personal interest in the case?
C. Is the witness prejudiced?
D. Does the witness have a good reputation for honesty and accuracy?