Is there actually a difference?
In the movie Bill and Ted’s Excellent Adventure, the slacker protagonists Bill and Ted offer this advice to the world: “Be excellent to each other,” and “Party on, dudes!” But are Bill and Ted running afoul of a rule regarding reciprocal pronouns?
“Each Other” Is a Reciprocal Pronoun
The phrase “each other” is known as a reciprocal pronoun because it shows a bidirectional action. For example, if Bill and Ted are being excellent to each other, that means Bill is being excellent to Ted, and Ted is being excellent to Bill. They’re practicing what you might call excellence reciprocity.
“One Another” Is a Reciprocal Pronoun
But Bill and Ted aren’t talking about being excellent just to Bill and Ted; they want each person in the world to be excellent to every other person. According to some grammarians, if we’re talking about more than just two people, we should use a different reciprocal pronoun: one another. In other words, Bill and Ted should more properly have said, “Be excellent to one another.”
English is unusual in having more than one reciprocal pronoun to choose from. It doesn’t set the record for the most reciprocal pronouns, because Korean has three, but most languages just have one. Chinese, Finnish, French, Classical Greek, German, Hebrew, Japanese, Russian, and American Sign Language, among others, all have just one reciprocal pronoun. Some languages, such as Spanish, Shoshone, and West Greenlandic, don’t even have that many. They use the same pronoun as both a reflexive and a reciprocal, so that the same sentence could mean either “We see each other” or “We see ourselves.”
“Each Other” or “One Another”?
The trouble with having a choice of reciprocal pronouns to use in English is that English speakers (and speakers of other languages, too) can’t stand to have more than one word with the same meaning. They’ll look as hard as they can for a meaning difference, and if one doesn’t exist, someone will create one. It’s happened with “healthy” and “healthful,” with “continuous” and “continual,” and many others. According to the Merriam-Webster Dictionary of English Usage (MWDEU for short) the first person to state that “each other” should refer to only two people and that “one another” should refer to more than two was George N. Ussher, in 1785.