Possible, Plausible, Probable, and Proven:The Four P's

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This is one of a series of articles on Genealogical Methods, prepared in association with The Tapestry. See Index for a list of related articles.

This page is currently under development.

Genealogists routinely have to assess a wide variety of data, deciding whether or not the data applies to the particular ancestor in question. Sometimes such decisions are easy to make, sometimes not. Sometimes people accept information that they perhaps should not. That can lead to considerable mis-understanding of who their ancestors were, and is often the cause of "confusions" in a particular lineage. The "Four P's" is a simple set of rules that may help in making better decisions: The Four P's are

  • Is this Possible?
  • Is this Plausible?
  • Is this Probable?
  • Is this Proven?


Its is often surprising how frequently genealogical data is presented for an ancestor that is not just wrong, but not even possible given the other data that's presented.

Common examples of this include dates of birth that suggest that someone a) was born before their mother was born or b) lived an extraordinarily long life (e.g., 150 years old at death). In America its also not uncommon to see indications that a European settler was born in a place that was not settled until well after their birth. As as an example of this, a check of Ancestry Family Trees shows many entries for Europeans being born in Jamestown, Virginia, before the colony was settled in 1607. The DOB's could actually be correct, but we can be quite confident that no European was born in Jamestown as early as 6 MAY 1585, as one entry for John Rolfe would have us believe.


Sometimes data will be presented that is not obviously in error, but if correct, would be truely extraordinary. For example, While an age of 150 is simply not possible, it could easily be true that an ancestor lived to an age of over 100. Its not common, though. Even in recent times, the vast majority of folks die before they reach the centennial of their birth. When data is encountered that might suggest someone lived to the ripe old age of 110, it probably should be accepted only cautiously. Possible, but not plausible.

Similarily, many genealogies on Ancestry Family Tree's give Pocahonta's POB as Jamestown. Its conceivable that she was born in this area, but it is strikingly coincidental that she was born in the exact location where the Jamestown colonists would establish their fort in 1607. Again Possible, but not probable.


Sometimes data can be both possible and plausible, but just not very probale. As an example of this, some of the same entries on Ancestry referred to above give the birth of Pocahontas (aka "Matoake"), wife of John Rolfe, and daughter of Powhattan, as 1595 in Jamestown. Captain John Smith tells us in in his work "A True Relation..." that John Rolfe married Pocahontas in 1614. We might presume that she was perhaps 20 years of age at this time. That would make a DOB of 1595 both possible and plausible. Indeed, we can go a step further and say that this is a probable DOB, at least approximately, as we know that she had a child by Rolfe when she visited England in 1616. That would not be very likely if she had been born much later than 1595, give or take a few years. So in absence of more concrete data about her, a 1595 DOB is possible, plausible, and indeed probable. It can not, however, be accepted as proven.