There are lots of symbols for peace: the dove, the olive branch, the v-shaped hand gesture. Unlike those first two, however, the peace symbol -- the wearing of which these days seems more a fashion statement than a political one -- is of much more recent vintage. Here's how it came about.
It was 1958. Worldwide concern over nuclear stockpiling and total annihilation was growing, and the British Campaign for Nuclear Disarmament (one of many such groups, albeit the only one headed by a prominent philosopher, namely Bertrand Russell) was getting ready for a big protest at Canterbury Cathedral. They wanted a symbol of their own they could wear as a badge, and hired a British graphic artist named Gerald Holtom to create one. After experimenting with designs involving a Christian cross inside a circle, he created the now-famous "crow's foot" design.
The crow's foot has been a symbol for death and despair since ancient times, which seemed a not-unfitting reminder of the disarmament movement goal -- stop governments from nuking us into death and/or the stone age. But Holtom's peace symbol also had a more literal meaning hidden within: it contained the semaphoric shapes for the letters "N" and "D" ("nuclear disarmament" -- seen at left). Semaphores are a means of visual communication at a distance using the arms or a pair of flags.
Holtom later elaborated on his creative process in an interview: "I was in despair. Deep despair. I drew myself: the representative of an individual in despair, with hands palm outstretched outwards and downwards in the manner of Goya's peasant before the firing squad. I formalised the drawing into a line and put a circle round it." Here's that painting:
The circle, of course, has lots of meanings, among them eternity and the unborn child. Once Holtom's symbol had been adopted not only by the group he designed it for, but the anti-war movement as a whole a few years later, the right wing got ahold of it and created their own set of interpretations. The John Birch Society, for instance, claimed that it was the Antichrist's "broken cross," purportedly devised by Nero as a nasty way to execute Saint Peter. Others claimed it was a medieval symbol for the devil, and that it bore a striking resemblance to a Nazi badge used during WWII.
Thanks to Cecil Adams for his fine research, who also pointed out that the Birch Society has tried to "re-brand" the peace symbol thusly: