It has a far less ambitious role, to resolve disputes in a peaceful, socially acceptable manner . It is simply an orderly alternative to violent arguments.
The disciplines and institutions that claim to be possessors of The Truth (like religions) or at least try to systematize the search for The Truth (like science or philosophy) or those that promise thorough if chaotic access to The Truth (like art, journalism and the internet) arguably have had no greater success in finding nonviolent solutions to society's problems.
Like science and philosophy, The Law relies on the idea of debate - adversarial presentation of evidence, cross-examination, and arguments - to reach decisions. Each side is assigned a position to advocate strenuously in opposition to the other.
Wigmore the English legal scholar, stated, "Cross-examination is the greatest legal engine ever invented for the discovery of truth. You can do anything with a bayonet except sit on it. A lawyer can do anything with cross-examination if he is skillful enough not the impale his own cause upon it."
The legal system works best when it retains this skepticism, demanding credible evidence amounting to a high degree of proof before reaching final decisions.
The Law is accordingly suspicious of so called "common sense" (sometimes known as "conventional wisdom"). The phrase itself needs to be parsed, studied and thoroughly examined.
It is "common" because it constitutes widely held beliefs based on lore, anecdotal evidence, collective experiences (also known as rumor and hearsay), and often cursory observations. The word "sense" in this sense has a dual meaning. Sense infers correctness, as opposed to nonsense; it also relates to things that appear to be true to the senses. Senses can be misleading; perceptions of correctness can sometimes be equally wrong.
For instance, common sense as expressed in a commonly held sardonic axiom, is that "if it looks like a duck and quacks like a duck, it is a duck." The law expresses this principle as an example of circumstantial evidence, which the law defines far more carefully, using a different example with the same message. (CALCRIM - jury instructions 223 & 224):
"Facts may be proved by direct or circumstantial evidence or by a combination of both. Direct evidence can prove a fact by itself.
For example, if a witness testifies he saw it raining outside before hecame into the courthouse, that testimony is direct evidence that it was raining.
Circumstantial evidence also may be called indirect evidence.
Circumstantial evidence does not directly prove the fact to be decided, but is evidence of another fact or group of facts from which you may logically and reasonably conclude the truth of the fact in question.
For example, if a witness testifies that he saw someone come inside wearing a raincoat covered with drops of water, that testimony is circumstantial evidence because it may support a conclusion that it was raining outside.
Both direct and circumstantial evidence are acceptable types of evidence to prove or disprove the elements of a charge, including intent and mental state and acts necessary to a conviction, and neither is necessarily more reliable than the other.
Neither is entitled to any greater weight than the other. You must decide whether a fact in issue has been proved based on all the evidence.
Before you may rely on circumstantial evidence to conclude that a fact necessary to find the defendant guilty has been proved, you must be convinced that the People have proved each fact essential to that conclusion beyond a reasonable doubt.
Also, before you may rely on circumstantial evidence to find the defendant guilty, you must be convinced that the only reasonable conclusion supported by the circumstantial evidence is that the defendant is guilty.
If you can draw two or more reasonable conclusions from the circumstantial evidence, and one of those reasonable conclusions points to innocence and another to guilt, you must accept the one that points to innocence.
However, when considering circumstantial evidence, you must accept only reasonable conclusions and reject any that are unreasonable.
This cautionary clause is an expression of widely told folk tales that reveal the wisdom of skepticism in the face of apparently convincing indirect or partial evidence.
One of my favorites is the tale of the six wise men examining an elephant. Each touches a different part of the elephant and draws conclusions based on the limited evidence. One blind man feels the leg and concludes it is a tree. Another the side and envisions a wall. And so on. (See the interesting Wickipedia article, noting the derivations (Indian religious texts) and variations.
In logic, the problem is sometimes called the fallacy of exclusion, or of insufficient sampling (in statistics). In policy making, this fallacy can lead to disastrous results. When the perceiver expects or desires a particular result, intentional (or negligent exclusion) is called "selection bias."
Courses on logic are offered in colleges, but usually they are hidden in Philosophy departments. The basics should be taught as a pre-requisite to entry into any other area of study, because it teaches the one sine qua non, a way to approach any issue.
Our invasion of Iraq, of course is the most blatant and obvious example of this fallacy. The Bush administration drew conclusions from circumstantial evidence derived from often speculative and conclusionary intelligence gathering that conformed to their "belief" that Hussein was a threat, while disregarding, suppressing or minimizing contradictory evidence and inferences.
Their arguments shrugged off "legalistic" objections to the quantum of proof, proposing the common sense based dogma that national security required a lesser standard of proof than beyond a reasonable doubt. Considering the magnitude of the potential threat, they concluded that it was better to err on the side of action.
This impulse — to make decisions based on fear is precisely what causes juries to convict persons accused of heinous crimes on less evidence than they would require if the crime was less serious — is an example of common sense that is in fact contrary to logic, especially as applied to criminal cases.
Logic would seem to demand that the greater the potential punishment, the more certain should be the conclusion of culpability. But, even though the law demands presumption of innocence and proof beyond a reasonable doubt, some crimes are so inflammatory that those cautions are tossed. The instincts of jurors is to err on the side of their fear of releasing an accused child molester, serial killer or gang member.
Another fallacy of common sense is what I call the "who-could-be-so-stupid" fallacy. It proceeds from the assumption that people act in their own best interests, and are not likely to act in ways that expose their faults. Juries sometimes apply it to defendants, jumping to conclusions of innocence and often apply it to alleged victims and witnesses as well. Police officers often benefit from this presumption when jurors conclude that a police officer is telling the truth because "he has nothing to gain by lying."