Expert-witness – someone qualified to make a personal declaration about the nature of the fact in question.
Historiography – “concerned with the discovery, use, and verification of evidence. The historian traces influences, assigns motives, evaluates roles, allocates responsibilities, and juxtaposes event in an attempt to reconstruct the past. Reconstruction is no wiser, no more accurate or dependable than the dependability of the evidence the historian uses for his reconstruction.”
Hearsay evidence – a.k.a rumor or gossip. An assertion or set of assertions widely repeated from person to person, though its accuracy is unconfirmed by firsthand observation.
Common knowledge evidence – A way to support one’s arguments. Most useful in providing support for arguments which lack any real controversy.
All information is biased because all information goes through an interpretation process. The credibility of the evidence you use can be enhanced by:
Specific Reference to Source: Does the advocate indicate the particular individual or group making the statements used for evidence? Does the advocate tell you enough about the source that you could easily find it yourself?
Qualifications of the Source: Does the advocate give you reason to believe that the source is competent and well informed in the area in question?
Bias of the Source: Even if expert, is the source likely to be biased on the topic? Could we easily predict the source’s position merely from a knowledge of his job, her political party, or organization she works for?
Factual Support: Does the source offer factual support for the position taken or simply state personal opinions as fact?
In his book, Argumentation and Debate, Austin J. Freeley discusses the uses of evidence. He says that the various types of evidence can be use in two ways:
To establish Conclusive Proof for your position. Conclusive proof is using evidence in such a way that the law will not permit it to be contradicted, or that it is strong and convincing enough to override any objections to it.
To establish Circumstantial Proof for your position. This is where the various types of evidence are used to form a link strong enough to prove your point. Using the different types of evidence as support gives the argument a the strength needed to establish the accuracy of your argument.