The Purist has a pristine (but perhaps smaller) family tree because no data is incorporated unless it’s proven beyond a doubt, preferably with documentation. The Pragmatist isn’t afraid to put unproven, undocumented information into the family tree because, well, if you don’t, you won’t get far very fast. And frankly, much of the source material is unproven and undocumented.
Most family history researchers land on a spectrum somewhere between The Purist and The Pragmatist. I’m nowhere near The Purist, because when I encounter new data, if there are several points of agreement with my existing database, I joyfully copy the new material into my family tree. Are there errors in that new material? Possibly. Likely. The dirty little secret of genealogy is that there are always some errors and omissions.
My database, built over 20 years, is approaching 9,000 individuals. Some of them aren’t even in my family tree, but “floating” in the periphery as individuals who “might” be related. The majority of my source material has been family trees made by others who have people in common with mine. This is not really research but copying parts of other people’s trees. No documentation.
Yet the efficacy of my method has been vindicated when I go to Ancestry.com and connect with a person who shares small amounts of DNA with me. The ancestor we have in common is way back in the 1600s in colonial America! If my tree were inaccurate at any point back to that colonial kin, the other descendant would not be a DNA match. I share Early American relatives with over a dozen previously unknown individuals, and we have the DNA evidence to prove it.
If you’re going to apply for membership in a lineage society, by all means, learn the qualifications and do the documentation. If not, relax and get the documentation when you can, but don’t be afraid to build your tree without documentation.
There’s always the delete button.