"Boolean or" or "boolean or"?

I was writing the text for some new error messages for the expression tree library the other day. When I ran them past our user education specialists (that is, the people who will be writing the documentation to explain the error messages), one of them pointed out that “Boolean” is an eponym -- a word named after a person -- and therefore should be capitalized.

And indeed, she was correct. Boolean logic is named after its inventor, George Boole (1815-1864).

That got me thinking, which often leads to trouble.

English writers do not usually capitalize the eponyms “shrapnel” (Henry Shrapnel, 1761-1842), “diesel” (Rudolf Diesel, 1858-1913), “saxophone” (Adolphe Sax, 1814-1894), “baud” (Emile Baudot, 1845-1903), “ampere” (Andre Ampere, 1775-1836), “chauvinist” (Nicolas Chauvin, 1790-?), “nicotine” (Jean Nicot, 1530-1600) or “teddy bear” (Theodore Roosevelt, 1858-1916).

However, we do capitalize “Darwinian evolution”, “Victorian morality”, “Elizabethan plays”, “Dickensian stories”, “Machiavellian politicians” and “Orwellian surveillance”, so perhaps we should capitalize “Boolean logic”.

I think the actual guideline to follow here is that we capitalize eponyms only if they are adjectives. Once they become nouns, we quickly stop capitalizing them.

Of course, that then doesn’t explain why we do not capitalize “caesarian section” or “draconian measures”. Expecting that much consistency from English is asking rather too much.