We conduct a reasonably exhaustive search in reliable sources for all information that is or may be pertinent to the identity, relationship, even, or situation in question.It may be easier to define what is not a reasonably exhaustive search, than what is not. The difficulty is in determining an objective, rather than a subjective, definition.
When I had a number of small children at home, it was common to "lose" shoes or socks or other small items. The children always claimed that they had looked for the item exhaustively. It was never surprising to find the object in an obvious and sometimes highly visible location. I sometimes have the same experience helping people with their genealogical research. In fact, I had an experience with this problem just this last week. Several of the volunteers at the Mesa Regional Family History Center were trying to help a patron with a search for his parents. The patron who was obviously very new to genealogy had no idea where to look. However, the volunteers were having trouble finding any information. This was a "missing sock" issue. The obvious place to look was the Social Security Death Index (SSDI) where I found the man's father in a matter of minutes. I am not faulting the volunteers at the Mesa FHC, but I went on and found the father's military record in Ancestry.com and a U.S. Census Record.
What I am using this example to point out is that the patron didn't have time to go on any further and walked out with three photocopies of records. I will likely never know if he goes any further in his search. The point of this example is that many researchers act just like the patron. As soon as they find something that looks like a document, i.e. a Census record, a SSDI entry, or some similar entry and away they go. That finishes that research, check off another relative.
The problem with using a word like "exhaustive" is the connotation that the search would never be over. That is the reason for using the modifier, "reasonable." But the real question is what I said above, is this an objective or a subjective standard? If it is subjective standard, then it is not a standard at all. The patron in my example did a "reasonably exhaustive" search from his standpoint, about ten minutes to be exact with me doing the searching, and so he is own his way. I guess I shouldn't complain, his search was better than no search at all and he did end up with documents.
If that is where we are at in genealogy, then I might as pack up and go home. (Oops, I forgot, I am home). Seriously, what do we have to do to meet the standard? I would note that the standard of an exhaustive is not subjective to the extent that the types of documents that can be used to substantiate any given fact are finite and reasonably well known. "Reasonable" in this context can have only a narrow range of meanings. It does not mean look for ten minutes and then quit. What it does mean is to consult all of the available types of records that might have a bearing on a particular research goal. A search of the SSDI, the U.S. Census and Ancestry.com is not an exhaustive search by definition, reasonable or otherwise. 2nd Corinthians 3:6 says, "The letter killeth, but the Spirit giveth life." This is exactly true in genealogy. In looking at the issue of a reasonably exhaustive search, we need to focus more on the search and less on trying justify ending the search after an unreasonably short time or effort.
The purpose of discussing this issue is not to discourage researchers, but to encourage more effort and to expand the horizons of research to include all of the possible records that are now so often ignored. My recent posts about copying user submitted family trees is a case in point. Incorporating information in your records without a source or citation to a source is not consistent with the spirit of doing reasonable exhaustive searches. In addition, confining your search only to those records that are available online is also outside of the term "reasonable."
The issue for some researchers is knowing when they have reached the limit of reasonable. I would suggest asking this question of yourself, "Have I looked at every type of record that may have existed at the time the even occurred?" If the answer to that question is no, then the search may be reasonable, but it is not yet exhaustive.