PRINCIPLES FOR
EVALUATING AND CRITICIZING HISTORICAL DATA:

1. Multiply Sources

2. Integrate Sources by Comparing Them
a) With manuscript copies, collate them
b) With documents
--Compare sources with each other
--Check against calendars
--Check against standard reference books
--Check against your own knowledge of the period

3. Evaluating the Relative Quality of Your Sources
a) Distance from the subject
--Prefer the primary source to the secondary source: i.e. the eyewitness to the hearsay account
--Prefer the contemporary to the later source: i.e. the diary to the memoire, the contemporary chronicler to the later historian
--Prefer the socially near to the socially distant
--Prefer the geographically proximate to the geographically distant
b) Expertise: Prefer the expert to the inexpert
c) Prefer the unbiased to the biased; compensate for bias when necessary, privileging sources that testify against their normal biases
d) Reject forgery, lies and fraud (except as evidence of the mentality of forgerers, liars, and swindlers).