The word "rational" is defined as based on or in accordance with reason or logic. As genealogists I assume, as a group, we aspire to rationality. Although my observations of the data produced by many individual genealogists would seem to belie that assumption. As Bertrand Russell is supposed to have said, "It has been said that man is a rational animal. All my life I have been searching for evidence which could support this."
It is rational to build a pedigree one event and one individual at a time. It is irrational to jump into the middle of a family line and start working without considering all the steps it takes to support the conclusions at the level at which you begin. Almost every time I help someone begin the steps necessary to discover a family line, I deal with irrationality. Fundamental to this irrationality is the supposition that genealogy can be a productive activity without proving each ancestral step. Quoting Rene Descartes, "When it is not in our power to determine what is true, we ought to follow what is most probable." Without investigation, you cannot determine what is either rational or most probable.
In a number of cases during the past week or so, I have had people start investigating their families before they had even a modicum of sources establishing their most proximate generations. If I were to claim that they owed me a considerable sum of money, almost to the person, they would require proof of my claim, but when it comes to genealogy, it is enough is Aunt Mabel or whoever, put the information on a family group record or that it was written in the published family history. A rational mind rejects unsupported assertions.
I am not implying that we become obsessed with proof to the extent that we lose our ability to decide and move on, but I am saying that genealogists should only accept that level of certainty, they can personally accept as proven by a preponderance of the evidence and never forgetting that additional evidence my change the accepted facts. The Genealogical Proof Standard is primarily procedural. It basically says that if you follow a certain methodology your will obtain a level of certainty and proof. For example a reasonably exhaustive search with a citation to reasonable sources. So, proof is procedural?
Correct, proof is procedural to the extent that achieving a certain level of believability or "proof" requires a consistent methodology, but ultimately proof is subjective. It is what you believe after you have seen the "evidence." The key here is seeing the evidence. So then you come back around to the Genealogical Proof Standard and the reasonably exhaustive search.
I frequently get the question, phrased in different ways, "do I have to start all over again and go through my pedigree? I have thousands of names." The real questions is whether you "went through" the pedigree in the first place? Where did the thousands of names come from? If you did the work and have the sweat to prove it, then by all means start where ever you want and move on from there. But if you inherited your information from someone else, how about reaching a reasonable level of certitude at every step before you move on doing research out there in the cloud?