Circumstantial Evidence
In most cases in court such direct evidence is the exception rather than the rule, for a man attempting crime would shun circumstances in which his crime would be witnessed. Indirect evidence—circumstantial evidence—is much more usual. It lacks the certainty of direct evidence, yet from the known facts presented it is often possible to secure almost the same certainty as from direct evidence.
In serious crimes, such as murder, juries are extremely cautious about convicting upon circumstantial evidence. There are many chances of error in making chains of evidence. In indirect evidence a group of facts is presented from which a conclusion is attempted. Suppose a boy had trouble with a farmer and had been heard to threaten to get even. One day the man struck him with a whip as he passed on the road. That night the farmer's barn was set on fire.
"Indirect evidence—circumstantial evidence—is much more usual."
Neighbors declared they saw some one running from the scene. Next day the boy told his companions he was glad of the loss. Circumstantial evidence points to the boy as the culprit. Yet what might the facts be?
In presenting arguments get as much direct evidence as possible to prove your statements. When direct evidence cannot be secured, link your indirect evidence so closely that it presents not a single weak link. Let the conclusion you draw from it be the only possible one. Make certain no one else can interpret it in any other way.
When you present evidence be sure it completely covers your contention. Be sure it is clear. Be sure it fits in with all the other facts and details presented. Do not let it conflict with usual human experience. Consider the sources of your evidence. If you do not, you can be certain your audience will. Are your sources reliable? Is the information authoritative? Is it first-hand material, or merely hearsay? Is it unprejudiced? Many of the other facts for evidence have already been suggested in the chapter on getting material.