Brian Garner’s Usage Tip of the Day (7 July 2009) holds, in part:

“ ‘Jr.’ and ‘Sr.’ aren’t used unless the names are identical. So the second Bush president (George W[alker] Bush) is not a junior, the father’s name being George Herbert Walker Bush. But some journalists use ‘Jr.’ and ‘Sr.’ as a kind of loose shorthand {Bush Sr. / Bush Jr.}.”

“When the names are identical” is a matter of context: how the names are spoken or written in a particular book, broadcast, etc. Although Garner is correct that “George W. Bush” should not be written “George W. Bush, Jr.” (because the elder Bush is not “George W.”, but “George H.W.”), the following pair should be acceptable:

George Bush, Sr.

George Bush, Jr.

It is only in contexts that include middle names or initials that the names, as written, become un-identical. Therefore, the “loose shorthand” is correct.

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