"Evidence is none the less effective because it is circumstantial, if it be consistent, connected and conclusive."

...

"In theory:

Modern genealogy draws heavily from law in its handling of evidence. Yet genealogy requires a higher standard of proof than does most civil litigation, and attempts to define genealogical concepts by legal terms creates confusion. Consider this comparison:

• The justice system requires that a date be set for trial, that all known and valid evidence be considered at this time, and that a decision be made then and there on the basis of the evidence. To avoid clogging the court system, the law permits decisions to be made in the closest of cases - even when the evidence on one side barely outweighs that on the other. This is the legal standard of proof called preponderance of the evidence.
• Genealogy rarely sees an arbitrary time or deadline by which one must decide the parentage of a distant forebear. If clearly convincing evidence does not exist to accept or reject a point, the genealogist can - and should - simply delay a decision until suitable evidence is found.

As careful genealogists, when we thoroughly exhaust all potential resources, we will carefully analyze each element and apply at least the points set forth in this chapter. If the weight of the evidence suggests a reasonable conclusion, we will labor to disprove our hypothesis as diligently as we labor to prove it. When we find contrary evidence, we will adequately and logically rebut it - or else delay our decision until clearer support can be assembled. When we are convinced that all valid evidence points to a conclusion that we and others of experience and rational thinking can accept as clearly convincing, then we may be ready to present our case.

To argue a case - whether upon an assemblage of circumstatial evidence or a resolution of conflicting evidence - we must reduce our argument to paper. The object is a clearly written, logically reasoned, totally documented summary of the problem, the records consulted, the methodology used, the evidence found, and the conclusion we believe is justified."

Elizabeth Shown Mills, Evidence!, pp. 46-8.

...

"The Case Is Never Closed On A Genealogical Conclusion"

"The reliable analysis of any piece of historical evidence is a complex process. As good genealogists, we must repeat this process endlessly, applying the principles discussed in this chapter to every piece of evidence that we find. We also recognize that no decision regarding identity, parentage, origin, or other genealogical detail can be considered definitive. Just as scientists revise their theories in the wake of new discoveries, so do genealogists and historians. Any decision we make today could be changed tomorrow by the discovery of a new record.

In sum:

As careful genealogists, we cannot apply an easy, generic label - reliable or unreliable - to any document, much less any type of document. We cannot assign numerical values and add up a document's score to decide whether we should trust it. Under some misleading systems that hve been proposed, a dubious factoid repeated many times can seemingly outweigh an actual fact from a single, impeccably reliable source.

Instead, we must mentally appraise the credibility of each detail in each document on a fact-by-fact, circumstance-by-circumstance basis, considering all the factors outlined in this chapter. As we acquire a historical and social perspective of an ancestor's place and time, as we accumulate experience in evaluating the evidence we find, this phase of research becomes a less perplexing and a more fascinating and stimulating challenge."

ibid, pp. 57-8