The Difference Between a Source, Information, and Evidence
These three words sound interchangeable. They are not. Understanding the difference between a source, the information it contains, and the evidence that information provides is the single most important conceptual leap in genealogy. Once you see it, you will never look at a record the same way again.
What Is a Source?
A source is the container. It is the physical or digital object you looked at — the death certificate, the census page, the church register, the family bible, the letter in the attic, the gravestone in the cemetery. The source is not what it says. The source is the thing itself.
This matters because the same piece of information can come from different sources, and the source it comes from affects how much you should trust it. Your grandmother's birth date might appear on her birth certificate, on her death certificate, in the 1920 census, and in her family bible. Each of those is a separate source. Each one was created at a different time, by a different person, under different circumstances. And each one might give you a slightly different date.
What Is Information?
Information is what the source says — the specific facts recorded within it. A death certificate is a source. The birth date written on that death certificate is information. The cause of death is information. The informant's name is information. Each piece of information within a single source may have a different level of reliability.
This is the concept that trips people up. A single source can contain both highly reliable information and completely unreliable information at the same time. The death certificate is an excellent source for the date and place of death — those facts were recorded at the time of the event by someone with direct knowledge. But the birth date on that same death certificate was provided by an informant who may have been guessing. The source is the same. The quality of the information within it is not.
What Is Evidence?
Evidence is what the information means in the context of a specific research question. The same piece of information can be evidence for one question and irrelevant to another. A census record showing a family in Ohio in 1860 is evidence that the family was in Ohio in 1860 — but it is also evidence that they were not in Virginia in 1860, which might matter if you are tracking a migration.
Evidence comes in two forms. Direct evidence answers the question explicitly — a birth certificate that states a person was born on March 14, 1892 directly answers the question "when was this person born?" Indirect evidence does not answer the question explicitly but contributes to the answer when combined with other evidence — a census record showing a person aged 28 in 1920 does not state a birth date, but it suggests a birth year of approximately 1891 or 1892.
Most genealogical conclusions are built on indirect evidence from multiple sources. You rarely find a single document that answers your question definitively. Instead, you gather information from many sources, evaluate each piece as evidence, and build a case that points toward a conclusion.
Why This Matters in Practice
Imagine you are trying to determine when your great-grandmother was born. You find her birth date in four sources: a birth certificate says March 14, 1892. The 1900 census says she was born in March 1892. Her death certificate says March 14, 1891. Her gravestone says 1892.
Without understanding the source-information-evidence framework, you might average the dates, pick the most common one, or go with whichever source you found first. With the framework, you evaluate each source separately. The birth certificate was created near the time of the event — strong. The 1900 census asked for month and year of birth and was recorded in 1900 — good. The death certificate birth date was provided by an informant decades later — weaker. The gravestone was carved after death based on family knowledge — weakest.
The conclusion: March 14, 1892 is supported by the strongest sources. The 1891 date on the death certificate is likely an informant error. You have not just found a date — you have evaluated the quality of the evidence and made a reasoned judgment. That is genealogy done properly.
The Practical Payoff
When you start thinking in terms of source, information, and evidence, two things happen. First, you stop accepting information at face value just because it appears in an official-looking document. Every piece of information gets evaluated on its own merits. Second, you start recognising when you have enough evidence to draw a conclusion and when you need to keep looking. A conclusion supported by direct evidence from one strong source and indirect evidence from three others is solid. A conclusion supported by one piece of information from one questionable source is not.
This framework is not academic theory. It is the practical tool that separates careful research from guesswork. Every time you find a record, ask three questions: what is this source? What information does it contain? And what evidence does that information provide for the question I am trying to answer?
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