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Proof Arguments & Case Studies

We couldn’t have been prouder!

It seemed like everybody who visited our booth at the RootsTech conference in Salt Lake City, Utah, was talking about Professional Genealogy. Preparation, Practice & Standards, edited by Elizabeth Shown Mills. A number of people mentioned that they had signed up for a home study course based on Progen PPS.  And no wonder, Progen PPS is a landmark volume with an abundance of new material and thought. As David Rencher FamilySearch’s chief genealogical officer has remarked about the book, “The collective talents of today’s generation of key influencers bring together unsurpassed knowledge of our craft that simply must be studied by novice and expert alike!” As Benjamin B. Spratling has observed, “Every chapter of ProGen PPS has been crafted by one of today’s best practicing genealogists, then assembled into a cohesive course of instruction by an editor known for decades as American genealogy’s top expert.”

From time to time we have excerpted pages from Progen PPS.  If you haven’t acquired your copy of the most important new reference book in American genealogy, consider the following excerpt on “Proof Arguments,”  by Dr. Thomas W. Jones, from Chapter 20, pp. 477-479. You will be glad you did.

Proof Arguments & Case Studies,  by Thomas w. Jones, PH.D., CG, CGL, FASG

Proof arguments lie at the core of quality genealogical work. With no vestige of bias, successful proof arguments establish the likely reality of an observable identity, event, relationship, or other status that the genealogist deduced from indirect or conflicting evidence. Proof arguments show how solutions to complex genealogical problems meet genealogy’s standard for proof. They present and explain the evidence and the reasoning that underlie conclusions about those identities, relationships, and events.


Genealogical proofs establish the truth of a genealogical conclusion arising from research and reasoning. They show and, if necessary, explain the support for a researcher’s deductions about an event, identity, relationship, or status that the researcher did not see. Besides arguments, genealogical proofs can take either of two other forms or a combination of both:

Proof statements are sentences or data items in situations where, after thorough research, a citation alone can adequately document an assertion . Specific supporting sources and the overall context make the statements’ accuracy obvious. They require no explanation. For example, citing an official marriage return helps establish a marriage date when an officiant and eyewitnesses signed the document and an official recorded it soon after the event. That single citation can be sufficient in genealogical contexts , as when other evidence shows that the bride and groom were children in parental households before a certain date and parents after then. Statements and data items supported by single citations cannot, however, provide proof when isolated from thoroughly documented contexts.

Proof summaries consist of listed items or a series of sentences or paragraphs that support and explain conclusions not evident from citations alone. Proof summaries most often apply in situations where direct evidence items with no significant inconsistencies support a conclusion. The documented statements supplement and corroborate each, often adding depth or breadth to a conclusion.

With no clear-cut divisions separating them, proof statements, summaries, and arguments are three points  along a continuum of complexity and length. Proof statements are the shortest option, applicable when a proof requires little or no reasoning to understand. Proof arguments are the longest option, applicable when evidence items significantly conflict, supporting direct evidence is absent, or both. Per genealogy standard 53, proof arguments discuss “challenging cases.” These arguments also can contain proof statements and proof summaries.

Proof statements, summaries, and arguments give answers to genealogical research questions but present the question and answer in varying ways:

For proof statements, the questions and answers are obvious. A marriage date, for example, implies the question When did the couple marry and gives its answer, as well.

A proof summary typically states the conclusion in a way that implies the question. For example: a statement that “John married his first wife between 1808 and 1814,” preceding a list of documented points supporting that range of dates, implies the question When did John first marry?

A proof argument places the question near its beginning. The question can be the argument’s title, implied by the title, or embedded in a discussion of the question and difficulties in answering it. It can be stated as a question, worded as a problem to be solved, or implied by the argument’s opening discussion. Once the question and its context are clear, the writer of a proof argument can provide the answer before or after presenting and explaining the supporting evidence-or both before and after. Providing the answer before the evidence often simplifies the discussion, making it easier for readers to follow.

As the most complex form of presenting genealogical conclusions, proof arguments run to hundreds or thousands of words. Each argument focuses on a research question and the answer the researcher has determined to be correct. The discussion establishes the question’s context, including the relevant people, places, and time periods. It covers all relevant research findings and contextual and research factors affecting the question and its answer.

Maintaining a focus on the research question and its answer helps to make a proof argument intelligible and is likely to persuade readers that the researcher’s conclusion is correct. Therefore, proof arguments ruthlessly omit information and statements that are not intrinsic to the argument’s question and its answer. Researchers, for example, cite or describe negative searches only when they help establish the research problem’s context or provide negative evidence. Like “blind-alley” searches , interesting but irrelevant bits of information can appear in research notes or elsewhere, but they should not appear in the proof argument or its reference notes.

Proof arguments can stand alone or appear in broader contexts. Family histories and genealogy-software “reports,” for example, can contain one or more proof arguments at points where they help advance a biographical narrative or family story. Even in those contexts, the argument should remain free of extraneous discussion. The prose can transition from a literary style for a family narrative to a technical-writing style for the proof argument and back again. Section headings before and after the argument can smooth those transitions from the family narrative to the proof argument and back to the broader essay.

Regardless of where made, proof arguments contain similar elements. These include logical structure, clear writing, and sound documentation  and sound documentation.