Q. Besides italicization, does “ceteris paribus” require an initial C? In an article of mine, I wrote: “With this notation, the ceteris paribus cost relevant to the source . . .” The copyeditor capitalized “ceteris” but not “paribus.” Why would that be?
A. I can only imagine that your copyeditor thought that “ceteris paribus” was some sort of species of the animal kingdom, perhaps a distant relative of the wood pigeon (Columba palumbus). Note also that, all things being equal, CMOS doesn’t recommend italicizing any Latin phrase common enough to be included in a dictionary like American Heritage or Merriam-Webster.
[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]