When Alan Greenspan retired two weeks ago as chairman of the Federal Reserve, USA Today bade him a friendly farewell: "Inscrutable Fed chief leaves impressive legacy."
"'Inscrutable chief?'" mused one observer. "He wasn't all that inscrutable. Most of the time he was really pretty scrutable."
"Scrutable"? What a lovely word! It dates from around 1600 and means "capable of being scruted." No. I misspeak. It means, according to Merriam-Webster, "capable of being deciphered." Alas, "scrutable" has disappeared from English discourse, but when "inscrutable" bobbed up with Mr. Greenspan, the adjective prompted a few ruminations on the variant prefixes that enrich our lovely language.
We fortunate Americans, said Thomas Jefferson, are endowed by our creator with certain "unalienable" rights. Did he mean "unalienable" or "inalienable"? You may play it either way. The "un" spelling dates from 1611, the "in" from around 1645. Today, some opinionated editors would regard the preferred spelling as "inarguable" (1875). More contemporary authorities would choose "unarguable" (1881).
If you are looking for a "rule" to guide you in this cosmic puzzlement, or even a pattern to suggest a preferred spelling, you will look in vain. The great Henry Fowler examined "un" and "in" almost 80 years ago in his seminal "Modern English Usage." He concluded, with his familiar twinkle, that (USE ITAL FOR UPPERCASE PREFIXES) "there is often a teasing UNcertainty -- or INcertitude --" about the negative form of an adjective. He added:
"The general principle that 'un-' is English and belongs to English words, and 'in-' is Latin and belongs to Latin words, does not take us far. ... The first part, when asked to solve real problems -- whether, for instance, 'unsanitary' or 'insanitary' is right -- seldom gives a clear answer."