In our genealogical study and training ,we are urged to question our sources. Who created the source? When was it created? Why was it created? These are important questions, and I can give you an example as to why they are important.
In my research for my current grant project on the family structure of St. Augustine, Spanish Florida, 1783-1821, I came across an excellent article by Sherry Johnson, titled "The Spanish St. Augustine Community 1784-1795: A Reevaluation" (Florida Historical Quarterly, 68:1 27-54, July 1989). In the article, Johnson discusses the ethnic/national makeup of the population of St. Augustine, and deals with a contention entrenched in the historiography of St. Augustine: that the Spanish population during that period was quite fluid and therefore not of much consequence in the affairs of the town. From a comparison of the census of 1786 with a town plan drawn up in 1788 (which includes owners' names for town plots) and the census of 1793, it appears the English and Menorcan components of the population were more stable, and therefore of more consequence in the town's history.
This evaluation stems from the work of Joseph Byrne Lockey, who transcribed and translated the censuses found on Reel 148 of the East Florida Papers, Bundle 323A. The East Florida Papers, the originals of which are at the Library of Congress, consist in Spanish records seized at the time of the United States' takeover of Florida in 1821. There are several censuses from 1783 to 1814 on Reel 148 of the microfilmed East Florida Papers, but not all of them bear dates. It has been difficult to discern which enumerations apply to which years. Lockey transcribed the entirety, and thought along with everyone else at the time -- the early to mid 1940s -- that there was one huge census from 1793, the census of 1786 which is dated and identified, and a few from about 1813-1814. However, when Lockey was working with this long transcription of the supposed 1793 census, he discovered that names appeared more than once, with changes in family composition and in ages of the individuals. He was able to figure out that there was more than one census recorded, and to figure out the years of each of them within a small margin of error.
However, in examining these censuses, according to Johnson, Lockey also reached the above conclusion -- that the Spanish population turned over fairly rapidly. He assumed that these were the government officials who served short terms and then returned to Spain or Cuba or wherever. This rapid turnover, as perceived by Lockey, led to the conclusion that the Spanish were not that tied to St. Augustine during the period, and were not that important.
The problem is that in looking at the 1786 census, Lockey, a historian, did not ask an important genealogical question (which, may I point out, is also an important historical question): Who created the 1786 census? WHY was the 1786 census created?
Johnson did more research, thinking like a genealogist, and came up with the explanation, and support for the idea that St. Augustine in the Second Spanish Period was very much a Spanish town with a very stable and significant Spanish or Spanish-descended population. It is well-known that the census was taken by the parish curate, Father Thomas Hassett (he was Irish). The census has a brief descriptive introduction signed by Father Hassett, in which he states that he did not enumerate the Spanish officials or the troops of the garrison of the Castillo de San Marcos. He took the census because he wanted to know how many protestant foreigners resided in St. Augustine, for whom and whose children he wanted to create a school to catechize these protestants in the Catholic faith.
For 20 years, between 1763 and 1783, St. Augustine had been under the control of England. When the Spanish returned, there was a decree that foreigners who wished to remain as residents of the town must swear allegiance to the King of Spain and must, if not already Catholic, convert to the faith. It was those protestants who had been permitted to remain whom Father Hassett wanted to enroll in his school. It follows, then, that Father Hassett would not have enumerated the Spanish and Spanish-descendant families in St. Augustine who were already Catholic and not in need of Father Hassett's schooling.
Johnson adduces much other evidence to show the importance of the Spanish and Spanish-descended population of St. Augustine.
We need to remember to question our sources, for doing so may prevent us from reaching erroneous conclusions.