In the metal type days, it was a separate "sort", a generic character not part of any particular typeface, and there was typically a single design. The first PostScript fonts included the pilcrow (it was part of the original Mac character set) and type designers began to adapt its design to fit the style of the font it was part of, including italicizing it.
If you want a font to look more traditional, leave it upright. But I agree with Craig that there are good reasons to italicize it.
Anything that wasn't traditionally part of the standard character set, like math operators and other symbols.
Also, I need to clarify my previous comment. I checked one of my old Linotype specimen books, and the pilcrow was part of the standard character set, at least in some fonts. However, it was always upright. They did make it bolder for bold fonts, and italic in italic fonts (but not always).
I think more and more the characters that previously were not italicized (at least in digital fonts) are being designed with italic forms. I don't think this is necessarily because more type designer are uniformed, but because stylistically it is more fitting as these characters have multiple typographic contexts.
I vote “yes” and make an italic pilcrow. In general, my default is to make all letters slanted in an italic font. I have a specific list of glyphs to keep upright in an italic, originally based on Adobe’s practice in this area.
Note that if a glyph is maintained as upright in an italic font, it may still need sidebearings or spacing adjustment, especially if it has an unusual vertical position (asterisk, trademark, copyright, and degree, for example).
There is also the code point U+2761 for an especially swashy and decorative pilcrow.
Would it be an idea to include upright characters as a stylistic alternates set? That would give more control of correct spacing, as opposed to switching in and out of italic in a word processor.
I guess I slant most things with a few exceptions: bar, brokenbar, estimated, plus any dingbat-like glyphs, like stars and other geometric shapes. Also, directional arrows.
I italicize almost everything in italic fonts. If editors and typographers want to get picky about equations, they can use roman font characters at their discretion.
In a couple if types (The Modern Suite) I included roman parentheses as a stylistic set, suitably kerned, in the italic, but now I don’t bother, as I figure it is less work, for typographers who know and care about such things, to change fonts and apply optical kerning, than go digging around in the Stylistic Sets.
Comments
If you want a font to look more traditional, leave it upright. But I agree with Craig that there are good reasons to italicize it.
And what other characters does this concept apply to? I've often wondered this...
Also, I need to clarify my previous comment. I checked one of my old Linotype specimen books, and the pilcrow was part of the standard character set, at least in some fonts. However, it was always upright. They did make it bolder for bold fonts, and italic in italic fonts (but not always).
So, never mind.
Note that if a glyph is maintained as upright in an italic font, it may still need sidebearings or spacing adjustment, especially if it has an unusual vertical position (asterisk, trademark, copyright, and degree, for example).
My list for a large font I am working on:
Would it be an idea to include upright characters as a stylistic alternates set? That would give more control of correct spacing, as opposed to switching in and out of italic in a word processor.
In a couple if types (The Modern Suite) I included roman parentheses as a stylistic set, suitably kerned, in the italic, but now I don’t bother, as I figure it is less work, for typographers who know and care about such things, to change fonts and apply optical kerning, than go digging around in the Stylistic Sets.