There is a concept in statistical testing called “the null hypothesis.” It would be somewhat difficult to perform experiments on our ancestors to check statistically what records they would leave behind under different conditions and learn the probabilities of those records being preserved to our time. Simply put, we can’t do statistical tests on our ancestors, but that doesn’t mean that the idea of the null hypothesis isn’t useful for genealogists.
Let’s say you are interested in an ancestor named John Doe. You know about when he was born and approximately where he lived. You look for records of a John Doe that match what you think that you know about him. You collect records but gradually realize that there is no way that they can all be records for the same person. For the sake of argument, let’s assume that it turns out to be pretty obvious that there are four different men named John Doe represented by your records. At that point, it might be tempting to wonder “Which of these men is my ancestor?” Is that really the right question to ask?
There is a hidden assumption in the question “Which of these men is my ancestor?” The assumption is that one of them actually is your ancestor. It isn’t obvious that is true. The null hypothesis would be that none of the men whose records you have collected is your ancestor. That is an important idea to check. Even if it isn’t done consciously, the alternative is to take the man who fits best and add him to your family tree. Yet that fit might not be good enough to rule out that null hypothesis that all the men on your list are wrong. There is one little phrase, just two words, that can be added to the question that help us to remember all the possibilities—”if any.” The question becomes “Which of these men, if any, is my ancestor?” Those two little words may not put you on the right road, but they at least help to make sure that you don’t accidentally close off the right road.