Is Genealogy An Exact Science?
By Donald Lines Jacobus, MA, FASG of New Haven, Conn.

"Science" is merely a word of Latin derivation meaning "knowledge." If we except mathematics, which is not so much a science in itself as a mode of measurement employed in all the sciences, there are no exact sciences. The more definitely measurement can be employed, the more exact a science becomes. Hence, astronomy and physics may be considered as reasonably exact sciences, though even here when we approach infinite magnitude, as of distance in astronomy, or infinite smallness, as of electrons in physics, and our measuring devices are not sufficiently acute, we discover a wide margin of inexactitude.

Sciences which relate wholly or in part to human nature are considered the least exact. History and biography may be exact as to dates, but in so far as they deal with human motives, the "why" of historical and personal events, they can never hope to be absolutely correct. Genealogy, as one of the sciences in which human nature is a factor, is considered to be one of the less exact sciences. As practiced by many of its devotees, it is certainly one of the least exact. Yet it is entitled to rank higher, provided only that proper scientific methods be pursued. The real object of genealogy is to establish lines of descent of human beings. Whether the motives of the inquirer be to make a study of heredity, or to join a certain society by proving descent from a qualifying ancestor, or mere curiosity to learn the identity of one's forebears, the line of descent is the essential thing. All else is incidental.

Among these incidentals are dates. These are important for purposes of identification of ancestors; they are the measuring device which helps to make genealogy an exact science. No one who lacks a mathematical mind can hope to become a genealogist of the very first rank, for it is necessary to deal with dates constantly.

The dates in themselves may not be utterly exact. The family Bible may differ a day or two from the town record of birth; it may even differ by an exact year. The date of death may not be precisely known, except that it falls between the making and proving of the man's will. Yet the dates, if ascertained and copied with meticulous care, are usually exact enough for the larger purpose of identification of persons.

Biologically, the genealogist is concerned with proving a line of descent; which means, proving the parentage of one individual at a time, then the parentage of his parents, and so on, step by step. How exact is this process?

We may as well concede, at the start, that the paternity of every child in a human pedigree is a matter of faith, or belief, not of proved fact. Although the present writer, like most genealogists, has excellent reasons for the assumption that an extremely high percentage of children were actually the offspring of their reputed parents, it is hardly necessary to call attention to the fact that a single infidelity on the part of an ancestress would be sufficient to invalidate the paternal ancestry back of that generation. Hence, biologically considered, it must be granted that genealogy is not as exact a science as could be desired, since an entirely unknown margin of error always exists, at least as a theoretical possibility.

The genealogist has no means of going behind the official records. The pity is, that he does not more consistently pursue the policy of depending on the official records for his conclusions. Every science must admit the possibility of a margin of error. But in most of the sciences, conclusions are reached only after the collection of all facts which might affect the matter, and after experimentation; which, in genealogy, means the setting up of hypotheses, the testing of these hypotheses by known facts, and the successful elimination of all but one hypothesis, which is then accepted as the only one which fits and explains the facts.

When these scientific methods are employed, by a genealogist of sufficient knowledge and training, genealogy becomes a reasonably exact science. Let us consider an example of scientific methods, to illustrate how they work. Peter Gubbins appeared, let us say, in the town of Straitsville, where his children were born between 1800 and 1820. The line has been traced back to this Peter, and his origin is sought. Using the splendid facilities that are now available to the genealogist in many of the older sections of the country, it is found that a Peter, son of John Gubbins, was born in 1775 in Freetown, some fifty miles away. The dates fit, but the identity of the two Peters is a mere assumption or guess, if we stop here.

We therefore collect every atom of evidence concerning Peter which is available in the records of Freetown, or at the county seat, or at the State Library. We find that his father John died in 1798, leaving a will in which he gave specified realty to each of his sons, including Peter. In the land records, we find that in 1801 Peter Gubbins "of Straitsvine" sold this land, the description of the property proving it to be the same which was given to Peter in his father's will. If we are lucky, Peter's deed may even specify that the land "was set to me from the estate of my father John Gubbins deceased." In any case the cumulative evidence is sufficient to prove that our Peter Gubbins of Straitsville was the son of John whose birth was recorded at Freetown in 1775. We are assuming, of course, that the Straitsville records have been thoroughly searched, and indicate that only one Peter Gubbins was living there in the period from 1800 to 1820; also that the U. S. Census shows but one Peter as head of a family in Straitsville in 1800,and 1810.

In the above illustrative case, we have attained a degree of proof sufficient even for legal purposes; we are no longer relying on guesses.

"Quite unnecessary," the amateur may retort; "the guess was correct in the first place." Very good: then let us consider another example, starting with the same premises. Again we seek the origin of a Peter Gubbins who appeared as a young adult at Straitsville in 1800; and again we find a Peter, son of John, born at Freetown in 1775. Again we make the same guess; but if we make a thorough search of the Freetown records, we shall discover that this time our guess is wrong. For the Freetown records may as easily (in this second example) reveal the following facts:

The will of John in 1798 gave land to his son Peter, but Peter did not sell it until 1805, when he called himself “Peter Gubbins of Freetown:” The description of the land proves the identity of this man with the son of John, and since he was still of Freetown after our Peter settled in Straitsville, he was apparently not the Peter we are seeking to trace. However, our search of the deeds shows that in 1810 Peter Gubbins "of Straitsville" sold all his right to realty in Freetown, reserving the dower interest of Widow Dorothea Gubbins. The birth of this second Peter is not found recorded, but in one of the parishes of Freetown we find the baptism of Peter, son of Thomas Gubbins, in 1778. We find that a Thomas Gubbins died intestate in 1808, administration being granted to his widow Dorothea; her dower was set out to her, but she failed to present for record a distribution to the heirs.

Here the only hypothesis that fits the known facts is that our Peter of Straitsville was the son of Thomas baptized in 1778, and that two years after his father's death he sold his interest in the property inherited from Thomas, reserving the life use which Dorothea held as her dower right. The case is genealogically proved by these records, and our first guess has been proved incorrect.

As will be pointed out in a future article, printed sources, even the best of them, too frequently contain errors. The only reasonably certain sources of information are the contemporary records, which a man made of himself and his family while he was living, or which were made concerning him by official recorders.

There are several reasons why scientific methods have been unpopular with many genealogical students and writers. First in responsibility is that all-too-human trait of laziness. It is much easier to make a "likely guess" than to collect data with infinite labor and attention to detail, and thereafter expend real thought on the analysis of the data. Second comes the factor of sheer ignorance. Many compilers of family histories quite evidently have no knowledge of the existence of documentary archives, and assume that the only way the early generations of their family can be put together is by accepting what little is to be found in print and guessing at connections.

A third and very important factor is that of expense. Many amateur genealogists and compilers cannot afford the cost of thorough research in documentary sources. With this factor, the present writer has an understanding sympathy. Yet it is an old maxim that "whatever is worth doing at all is worth doing well," and one may be entitled to ask whether it never occurs to perpetrators of the worst genealogical atrocities to give consideration to this maxim. And it may be observed that, despite the lack of funds to compile a worthwhile genealogy, the compilers nearly always seem able to raise the funds to publish their productions.

For the professional genealogist, as for the amateur, there are valid excuses for failure to take advantage of the opportunities for original research. The professional, dependent upon his work for a livelihood, is restricted by the limitations of cost set by his client, and these limitations frequently do not permit as thorough a search as should be made. Errors made by professionals very often are due to the fact that, to keep within authorized limits of expense, they were forced to rely to a greater extent than they desired on printed sources of information. No one is responsible for this situation, for a large number of those who employ the services of genealogists are not people of large wealth.

A final reason for the unpopularity of scientific methods in genealogy is the romantic temperament of some of those who pursue genealogy as an avocation or a hobby. To people of that type, scientific methods are a bore. It irritates them to be told that a line of descent, innocently accepted from an unmeritorious printed source, is incorrect. They like that ancestral line, and intend to keep it. Denial or question of its accuracy seems to them purely destructive and negative. With people of this temperament, genealogy is not a serious study: it is a mere diversion, and they derive more pleasure from the exercise of their imaginative talent than they could from grubbing for facts. They believe what they want to believe, regardless of facts and are scornful of evidence. Let us concede, without argument, that" genealogists" of this type are entitled to their opinions: just as those who believe that the earth is flat are entitled to that opinion. It is entirely natural that these temperamental enthusiasts should oppose scientific methods, and that with the uninformed their opinions may have weight.

It must be confessed, in view of such chaotic conditions, that genealogy in this country today is very far from being an exact science, although the many workers in this field who now employ scientific methods are doing much to make it one.

Donald Lines Jacobus, "Is Genealogy An Exact Science?" (Online:  ProGenealogists, Inc., 2004) [originally published in The American Genealogist, Volume 10, Page 65 (October 1933) and reprinted by permission].

To learn more about this important genealogical journal, and the articles they have published, visit http://www.americangenealogist.com/