Saturday, August 11, 2012

Negative Evidence

Negative Evidence - it's important too!

Image: Wikimedia. Reused under ©© Creative Commons Licence

"The first point [of research] is that we cannot hope to prove any proposition unless we look for negative evidence that might contradict it."  [Studies in Philology , Richard Lavin, Volume. 92, No.4, 1995, p383]

As family historians we are constantly searching for evidence of the existence of ancestors. Evidence is  not to be confused with information. Evidence is much more than information. It is the information which we analyse and evaluate and which we accept to have authentic relevance to our research.

For the most part in the process of our research, we look for positive evidence. Positive evidence is what every family historian hopes to find. It adds names to our family trees. Positive evidence that an ancestor is associated with our lineage, can only be proved, when our information is tested, and we have sufficiently eliminated all contradictory evidence. As family historians, we seek unequivocal proof that ancestors belong on our family tree. To achieve this end, we use evidence, both positive and negative to reach our conclusions.

Photo Sharn White © Copyright

As every family historian knows all too well, vast numbers of hours are often invested in research which yields nothing of concrete value, no positive evidence and no names to place on the branches of the family tree. The question could be asked - are these hours of research a waste of time? After a long day or night of what seems to be fruitless searching, it is easy to think time has been frittered away. An example from my own research, is that of  my great great grandfather, John Morrison, born in Aberdeen, in 1847 [according to the positive evidence I have discovered and recorded, including his death certificate and marriage record which states that his father's name was William]. In the 1851 Scottish Census, I found five males named John Morrison, each around the correct age, but no one with a father named William. I therefore located no positive evidence that any of these persons were my 2 times great grandfather. This is an example of negative evidence. By process of elimination, I determined which of the males named John Morrison were NOT my ancestor, narrowing my search to one possibility. John Morrison, aged 4 years in 1851, ( born in 1846), who was living with his sister and grandfather in Aberdeen, fitted the profile of my 2 times great grandfather. Before I could accept this negative evidence ( absence of evidence) as reliable evidence, it required testing to search for  evidence. I found  census and marriage records for each John Morrison found in the 1851 census, eliminating those who did not have a father named William and each John Morrison who did not marry Hannah Tait. In this way I eliminated those males who were NOT my ancestor. All negative evidence - but all leading towards a positive result (I hoped). The next logical step was to compare my negative evidence against any positive evidence in my possession. On the the marriage record (1869) of my 2 times great grandparents, I was fortunate enough to link a witness ( John Morrison's sister) to  the address of the grandfather with whom John and his sister were living in 1851.

Image Wikimedia Commons

In the absence of positive evidence, be assured, that you have not squandered time. The very absence of evidence of your own ancestor is EVIDENCE in itself.  The significant inferences which emerge, when we find no trace of an ancestor at all in our searching, are as important as the positive evidence we uncover. The commonly used terminology for this absence of evidence [ besides 'frustration'] is  NEGATIVE EVIDENCE.  In the absence of any positive evidence, it is feasible to arrive at a sound conclusion from the negative evidence that you have gathered during your research.

Ancestors do not always turn up in records... Image Sharn White © Copyright Creative Commons

Negative evidence is defined in Webster's Dictionary as : "evidence of any kind which suggests, via deduction or inference, the non - existence or non presence..."  
Elizabeth Shown Mills defines negative evidence as " inference one can draw from the absence of information that should exist under given circumstances" [Elizabeth Shown Mills, Evidence Explained, 1st Ed, Electronic. 200, p. 825 & 28.]

Each time a family historian proves kinship with a  forebear, the evidence is chronicled and preserved. Be it a record of a birth, baptism, marriage or death, a passenger list or a census record, positive evidence is documented, and our sources are recorded on our family trees. All genealogy programs provide various means by which to cite sources and evidence you have collected.  It  is also  important to document all negative evidence that you discover in your research. It is quite possible that the absence of records of an ancestor, may substantiate your case for relationship. Negative evidence eliminates who is NOT an ancestor and without doubt it proves where your ancestor WAS NOT. Negative evidence does not generate a 'copy' of a record as does positive evidence ( e.g. a baptism record) therefore it may be of benefit to keep a log of all negative evidence you find. Record keeping avoids time wasted re-checking records which you have already investigated.

Oops already checked this record! Image Sharn White © Copyright

When you find a birth entry which appears to be appropriate for an ancestor, negative evidence can be used effectively to substantiate your supposition.


My 2 times great grandfather, John Morrison, mentioned earlier, married Hannah Tait Gair in 1869, in Northumberland, England. On the marriage record, Hannah's father was named as Roger GAIR (occupation -Gardener) and her birth place was stated to be Cramlington, Northumberland.  Roger Gair was found easily in the 1861 census where I found Roger aged 46, (born 1815, Alnwick, Northumberland), wife Elizabeth, aged 44 born Cramlington, Northumberland) and daughter Hannah, aged 14 (born  in 1846, Cramlington, Northumberland). This Roger Gair was working as the head gardener at Heaton Park. It was not difficult to find a marriage for Roger Gair to Elizabeth TAIT, in Cramlington, in 1840, especially as Hannah's middle name was Tait. A birth for Roger Gair was located in Denwick, Alnwick, Northumberland on October 29, 1815. Any thorough genealogist will attest that a NAME is NOT proof of a person. Despite having a strong argument that this was my family of Gairs, I needed to prove beyond doubt that there was no contradictory evidence. This is where I used Negative Evidence to identify whether the Roger Gair I had found, was the person for whom I was searching.

Heaton Park where Roger Gair was head gardener.  Image Wikimedia Creative Commons


  • A search for birth records revealed no other person by the name of Roger Gair born in Northumberland in 1815 or in an expanded search up to 5 years before and after this date.
  • No other Roger Gair was born in Alnwick in around 1815.
  • No other family with the surname Gair had a father named Roger and a daughter named Hannah in the 1851 and 1861 UK census.
  • There were no other later records relating to a Roger Gair born around 1815 (ie death).
  • No other Roger Gair could be located whose occupation was that of a gardener. 
The Oxford Companion to Family and Local History, [ David Hey, 1996, NY.] provides the following description of negative evidence or negative proof   'a term much used in genealogical research. It denotes the attempt to prove that a name in a parish register is the one sought, by searching all the other records in the neighbourhood to make sure no one else of that name is recorded.'

In the absence of evidence to the contrary, known as Negative Evidence, I arrived at a soundly examined, well supported and reasoned  genealogical conclusion that I had found Roger Gair.

So, the next time you spend a day searching in your local archives and go home empty handed, or sit for many hours at your computer only to find no record of an ancestor, think positively of the negative evidence you are gathering. Keep records of all the searches you undertake.  Often, it is the absence of evidence that is in itself evidence.


  1. Go to the top of the class, Sharn, for another iluminating post illustrated clearly with well detailed wxamples.

  2. A very important point! It's all too easy to grab the obvious candidate and say "it must be mine". Rigorous elimination is part of being confident of our assessments. Great advice.

  3. I'm definitely sharing this post!

    Just the other day, I received a reply from the FBI about my great-grandmother's first husband. Supposedly he was a rum-runner during Prohibition, and no one knows what happened to him. I thought it wouldn't hurt to see if there is an FBI file on him.

    Well, there's not, so that means I have eliminated one possible avenue of learning more about him. I just document that in my family tree database, save the letter, and move on to state criminal justice systems next! :)

  4. Thanks for an important lesson learnt Sharn. I need to document where I have searched more thoroughly.

    Kylie :-)