Hierarchy of evidence
About
The hierarchy of evidence is a ranking of different types of evidence, to be used as a guideline for determining which evidence should be considered more credible when more than one type is available. Reasoning from evidence is how we determine what is most likely to be true about the universe. See hierarchy of truth for how to evaluate the credibility of a conclusion based on the methodology used for reaching it. Note that there is a certain amount of overlap between "evidence" and "truth", and any given claim or statement may be evaluated by either or both means depending on context.
The List
The following list is a first pass, and should not be considered complete, definitive, or certain.
- [PEV] physical evidence
- [AGR] agreed-upon facts
- [CIR] circumstantial evidence
- [EXA] personal/direct experience (includes argument from authority if the speaker is the authority)
- [INT] intuition / gut feelings
- [HSY] hearsay, rumor; this includes "I once heard", "lots of people are saying", and even "millions of people believe"
Evidence higher on the list generally trumps evidence lower on the list.
Each type of evidence may have a range of reliability, and it's entirely possible that more-reliable varieties of a given evidence-type should trump less-reliable varieties of a normally more-reliable evidence-type – e.g. the opinion of a professional with years of experience in a given field would normally trump circumstantial evidence that is not overwhelming, unless there is reason to suspect that the professional is biased.