Negative evidence is something that helps you draw a conclusion from the absence of a situation that should exist given the circumstances.
With negative evidence, it is the absence of something that is significant.
Here are some examples.
Patterns
In family history research, there are patterns of events. If those patterns are broken, this could be negative evidence of something that is not immediately obvious.
Before birth control, most couples had their first child within two years of marriage and then continued having children at gaps of between 18-24 months. If either of those patterns do not exist in a family, then this is negative evidence that something else has occurred. Perhaps the father had to leave for work or military service, or perhaps there was another child but you just haven’t found any records of them.
Women under a certain age (it differs by location) need parental consent or the consent of a guardian before they can marry. If a marriage records does not mention that consent was granted, this is negative evidence that couple were of legal age. Similarly, convicts needed permission to marry. If no permission exists, this could be negative evidence that they had served their sentence.
Negative evidence is very important in DNA research. The absence of DNA matches with descendants of your known ancestors is negative evidence of a non-paternal event or adoption along that line. In my own family history, for example, a complete absence of any matches on my father’s side provided negative evidence that he was adopted.
Missing or undiscovered records
If you have not yet found a death record, negative evidence may help you gather clues to the approximate date.
For example, if you track an individual through census records and they suddenly do not appear, this could be negative evidence that they died between the date of that census and the previous one.
Hypotheses
A research question can be converted into a hypothesis to provide a scenario that can be tested through research. The scenario is then used to predict events about which sources would have been created. If no such sources are found, this could provide negative evidence that the scenario is incorrect.
For example, if my great great grandmother Sophia was 101 when she died in 1931 and was born in Muswellbrook (as her death certificate states), then I should be able to find some evidence of her birth or her family in that locality at that time. However, a comprehensive search of the records for Muswellbrook around 1830 failed to reveal such records and this could be negative evidence that her name, age or the location were incorrect.
Negative evidence does not necessarily give us a definitive and defensible conclusion, but it can provide us with useful research leads. Investigating these leads may provide us with direct evidence from which we can draw defensible conclusions.
For more of my articles about research methods for family history, go to the Research Methods page.
Post last updated 4 June 2024