From the Introduction: THE THEORY PRESUMPTIVE PROOF.
THERE is no branch of legal knowledge which is of more general utility, than that which regards the rules of evidence. The first point in every trial, is to establish the facts of the case; for he who fails in his proof, fails in everything. Although the jurists hold the law to be always fixed and certain, yet the discovery of the fact, they say, may deceive the most skillful. No work has as yet appeared in the English language on the theory of evidence; and the nature of circumstantial evidence has been still less inquired into. The object of the present Essay is to inquire into some of the more general principles of legal proof, and particularly into that species of proof which is founded on presumptions, and is known to the English lawyer by the name of circumstantial evidence.
Evidence and proof are often confounded, as implying the same idea; but they differ, as cause and effect. Proof is the legal credence which the law gives to any statement, by witnesses or writings; evidence is the legal process by which that proof is made. Hence, we say, that the law admits of no proof but such as is made agreeably to its own principles.
The principles of evidence are founded on our observations on human conduct, on common life, and living manners: they are not just because they are rules of law; but they are rules of law because they are just and reasonable.
It has been found, from common observation, that certain circumstances warrant certain presumptions. Thus, that a mother shall feel an affection for her child, —that a man shall be influenced by his interest, —that youth shall be susceptible of the passion of love,—are laws of our general nature, and grounds of evidence in every country. Of the two women who contended for their right to the child, she was declared to be the mother who would not consent to its being divided betwixt them. When "Lothario" tells us that he stole alone, at night, into the chamber of his mistress, "hot with the Tuscan grape, and high in blood!" "Cætcra quis ncscit?" As the principles of evidence are founded on the observations of what we have seen, or believed to have been passing in real life, they will accordingly be suited to the state of the society in which we live, or to the manners and habits of the times. The following passage, in the excellent memoirs of "Philip de Comines," I believe to be perfectly true, because it is confirmed by other accounts of the general state of manners at the period when he wrote.
Louis XI. distributed, he asserts, for corrupt purposes, sixteen thousand crowns among the King of England's officers that were about his person, particularly to the chancellor, the master of the rolls, the lord chancellor, &c.
The truth of this narrative has never been called in question, because it is given by an historian of great gravity and character, and is illustrated by the manners of the age; yet although the author says that his design in writing of these transactions, is to show the method and conduct of all human affairs, by the reading of which such persons as are employed in the negotiation of great matters, may be instructed how to manage their administrations, we should find it difficult to give credence to such facts, if related of any modern lord high chancellor or officer of state of the court of England.