At some point in everyone’s genealogy research, there is time and place where we get stuck. It is then that we need to stop searching and start thinking. It is incredibly easy on the internet and genealogy websites to enter just one more search term, or just click through a couple more pages or results. After all, maybe the next thing we see will be the thing we are looking for! Unfortunately, it rarely works. When we get stuck, plowing on only gets us more confusion.
Here’s what to do instead: use logical reasoning.1 What do I mean? The application of formal logical arguments to break through where you are stuck. There are two ways to reach an answer to a problem. One is inductive reasoning and the second is deductive reasoning.
In inductive reasoning you start with a hypothesis, and then look for evidence to support or refute your hypothesis. This is essentially the scientific method you learned in high school science. An example in genealogy: Mary Campbell is in the 1880 Census at age 23 living in Reading, PA. But when you search on your favorite genealogy website, you get zero Mary Campell’s in 1870 and 1860. Where did she go? Using inductive reasoning you state the hypothesis that Mary Campbell was living in Reading in prior to 1870 and living with her parents. To test your hypothesis you look for evidence to prove and disprove it. In this case it would mean searching for all the Campbell families in Reading, PA and looking to see who has a 13 year old female in 1870 and a 3 year old female in 1860. You soon find such a family with a Alice Mary Campbell. A-ha! Is this your Mary Campbell? Possibly, and with more evidence gathering you can prove it or disprove it.
Deductive reasoning works in the reverse of inductive reasoning. With deductive reasoning, you gather evidence and then make a conclusion. This is similar to the work criminal detectives do in investigations of crimes. An example in genealogy: Mary Campbell is in the 1880 Census at age 23 living in Reading, PA. When you search on your favorite genealogy website, you get back seven Mary Campbell’s living in Reading, PA in 1870. Which one is your Mary Campbell? You stop searching and start thinking. Mary Campbell would have been 13 in 1870. You decide to add or subtract a year from 13 because her birthday could have been before or after the census. Mary was living on 4th Street in 1880, so you write that down too. Mary had siblings and parents, so you write their names down. Now you go back and look at the search results have a list of evidence to use to compare with the results. You can quickly go through the list and eliminate the wrong Mary Campbell’s to find the one you are seeking.
Deductive reasoning is the preferred method to use in genealogy because it starts from known facts and then looks for people who fit those facts. With inductive reasoning, you start with a possible answer first and you run the risk of not searching long enough to disprove your theory. Our human brains love to have answers and tie everything together neatly, and we don’t like to disrupt something that is settled. Using deductive reasoning helps us work around that.
Just remember, when you lose people in a specific time or place, stop searching and start gathering evidence. Look for more information on who they lived near, what church they attended, what other family they had in the area. Be a detective and gather, gather, gather. When you’ve got everything you can find, then use inductive reasoning to reach a conclusion. It’s just logic!
1 This writing was inspired by the National Genealogical Society Quarterly article “Logic for Genealogists” by B. Darrell Jackson, PhD, CG, published March 2017.