“Each other” and “one another” are both reciprocal pronouns. This means that whatever is happening between “each other” or “one another” is going in two (or more) directions; if John and Jane love each other, he loves her and she loves him. When students share their revision notes with one another, no-one is at a disadvantage come exam time. But is there a difference between the two expressions? Or are they the same as each other?
Some traditionalists – and even several usage guides – advise that each other should be used to denote a reciprocal relationship only between two entities, whereas one another refers to three or more people or things. When Cher sang “Love One Another” about 10 years ago, she was presumably advising many people to love reciprocally; had she been addressing just one couple, “Love Each Other” (according to these strict grammarians) might have been more appropriate. A brother and sister compete with each other; three contestants vie with one another for the main prize …
However, in practice these expressions are used more or less interchangeably, whatever the number involved. In South Carolina yesterday, it was reported that “Spartanburg beekeepers encourage each other.” I’m guessing there are more than two beekeepers in Spartanburg. In a discussion about the Trayvon Martin case, MSNBC’s Thomas Roberts talked about how Americans are “treating each other with such disdain it’s not even funny.” There are definitely more than two Americans out there in the world, so Roberts obviously doesn’t abide by this particular rule.
Merriam-Webster traces “the prescriptive rule” (of each other for two, one another for three or more) back to the writings of a grammarian, George N. Ussher, in 1785, but goes on to explain that Ussher had no foundation for distinguishing between the terms whose interchangeability had been established many centuries earlier. “There is no sin in its violation,” reassures MW about the restriction, which has never existed in practice. Most modern dictionaries define the terms as interchangeable.
Fowler is relaxed about the interchangeability of the reciprocal pronouns. In the second edition of his Modern English Usage, he explains: “Some writers use each other only when no more than two things are referred to, one another being similarly appropriated to larger numbers; but this differentiation is neither of present utility nor based on historical usage. The old distributive of two as opposed to several was not each but either; and either other, which formerly existed beside each other and one another, would doubtless have survived if its special meaning had been required.
There is one situation, arguably, in which one another might be the preferred choice of expression, and that’s when talking about an ordered series (often temporal) of events or stages. “The relay runners passed their batons seamlessly to one another,” suggesting a handover one after the other. New York’s Daily News described today how customers were “pick[ing] up one another’s bills in [a] chain reaction at Massachusetts’ Heav’nly Donuts”. Here there’s a clear indication of more than two people in relationships that move forward in time. “The soldiers followed one another onto the parade ground” would sound slightly awkward if each other were substituted (unless there were only two of them).
One small word about possessive usage: The Sun reported today that “lovebirds Lia Benninghoff and Aro Draven share an unusual bond — they drink each other’s blood.” Each other and one another act as singles (ie. the apostrophe goes between other or another and the ‘s’) when they have possessions — whether they’re vampires or anyone else. They each own it, despite sharing it, and it belongs to only one of them at a time.