Mission 19: Weighing the Evidence — Introduction to the Genealogical Proof Standard
How to Know What You Think You Know
You’re three generations deep into a family line when you find it—two death certificates for the same ancestor, with different parents listed on each. One says his father was James. The other says William. You’ve been building your tree on one of those names for two years. Which one is right?
And how would you even know?
This is the moment that separates someone who collects records from someone who evaluates them. You now have an impressive toolkit: censuses, vital records, newspapers, court files, land deeds, immigration papers, church registers, and maps. You know where to find things. This mission answers what to do once you’ve found them.
The answer is a five-part framework called the Genealogical Proof Standard. It sounds formal—and it was developed by the Board for Certification of Genealogists—but it’s really a structured way of asking: Do I actually know this, or do I just hope it’s true?
The Five Elements
The GPS isn’t a single test you pass or fail. It’s five habits that, practiced together, turn a hunch into something you can stand behind.
Reasonably exhaustive research. You’ve checked all the sources a competent researcher would check for this question in this time and place. Not every source in the world—just the ones that matter. For our two-death-certificates problem, that means looking beyond death records: checking earlier census returns, marriage records naming parents, probate files, and church registers. If you’ve only consulted one source type, your research isn’t exhaustive. It’s a first impression.
Complete and accurate citations. Every claim traces to a specific document. Not “I found it on Ancestry,” but which collection, which image, and which repository holds the original. Good citations aren’t fussy decoration. They’re how future-you retraces your steps when new evidence changes the picture.
Skilled analysis and correlation. You’ve examined each piece of evidence in context, compared records against one another, and drawn reasonable inferences. A birth date on a census is information. That date, when you’re asking whether someone was old enough to serve in the Civil War, becomes evidence. Not every piece of information is relevant to every question.
Resolution of conflicting evidence. When two sources disagree—and they will—you’ve explained which one you trust more and why. Who was the informant on each death certificate? A sibling likely knew the deceased’s parents better than a hospital clerk recording what a grieving spouse said. You can’t ignore the source you don’t like. You have to explain the conflict.
A soundly reasoned, coherently written conclusion. Your reasoning is written down in plain language. If you can’t explain why you believe James is the correct father in a few clear paragraphs, you haven’t proven it. You’ve picked your favorite.
The Hierarchy: Information, Evidence, and Proof
These three words aren’t interchangeable.
Information is raw data in a source—a name, date, or place. It doesn’t care what you’re looking for. Evidence is information relevant to a specific research question. Proof is a conclusion supported by evidence that meets all five GPS elements. Evidence doesn’t become proof because you found a lot of it. It becomes proof when you’ve tested it.
Think of it this way: a folder full of photocopies is information. A folder organized around a specific question, with sources compared, conflicts resolved, and reasoning explained—that’s proof.
Three Kinds of Evidence
Direct evidence answers the question plainly. A marriage certificate stating Thomas married Clara on February 2, 1915 directly answers “When did Thomas marry Clara?” No interpretation required.
Indirect evidence contributes to an answer only when combined with other sources. Family records say Clate was the second child. County records show the second child was born in 1898 but don’t give a name. Neither record alone gives Clate’s birth year, but together they do.
Negative evidence is the silence that speaks. If a marriage register notes “guardian’s consent” whenever a minor is involved and one entry has no notation, that absence is evidence both parties were of legal age. Sometimes what’s missing tells you as much as what’s there.
You Don’t Need to Write a Dissertation
The word “written” scares people. GPS requires a written conclusion, and many hobbyists picture an academic paper with footnotes and peer review.
It’s not that. A proof summary can be a short paragraph. For a straightforward parent-child or spousal connection, a few sentences with citations may be enough. For a complex conflict, a page or two explaining the evidence and reasoning is appropriate.
The point isn’t publication. It’s to show your work so when a new record surfaces five years from now, you—or someone who inherits your research—can evaluate your reasoning instead of starting over.
Your Mission
Pick one ancestor you’re “sure” about. Choose one connection you’ve never questioned—parent to child, spouse to spouse, immigrant to port of arrival. Apply the five elements. Have you searched exhaustively? Are your citations complete? Have you evaluated the evidence and resolved conflicts? Have you written it down?
Write one paragraph explaining why you believe the connection is correct, with citations. If you can do it confidently, you’ve met the Genealogical Proof Standard for the first time. If you can’t—if you realize you’ve been building on assumption—congratulations. You’ve graduated from collector to analyst.
Granny says: “Finding a record is a good day’s work. Knowing what it proves—that’s the work of a real genealogist.”