Today’s Brevity has an alien questioning an earthling. He tells the earthling, who is wearing a suit and tie, that he will blow up the planet unless he answers all of his questions. The eathling answers the first two questions correctly, but is stumped by the question about the prupose of ties. The earth is blown up.
To consider the necktie is really to consider clothing. The necktie has no utilitarian purpose, but that is not the only purpose of clothing. Clothing is not just utilitarian and protective, but also communicative. The ideas that it convey may be that certain body parts are sexually provocative, such as the hajib covering the hair, or that the body part is covered in such a way as to provoke desire while at the same time covering, such as the evening gown. It may also convey occupation, doctor, businessman, nurse, hooker, and so on. So what does the necktie communicate?
The tie has an obvious phallic resemblance, but that only applies to one style of tie, and cannot be said to be true of the bow-tie. Of course, the bow-tie may convey a different message, one that is less aggressive than that of the long tie, and that seeks to differentiate its owner from the male wearing the long tie. The tie can be a form of display, and an ostentatious representation of wealth. A Versace or Brioni tie can cost as much as $200 or more, and while a man may not be able to afford a Versace or Brioni suit (up to $7,000 for a Brioni), afford the tie that conveys an impression of wealth and power. So the tie can function as a part of a courtship display.
The tie is also the only part of a man’s uniform that is not a single color piece of drab. The standard uniform, at least for AWEMs, is pants and jacket in a solid color along the blue-black-gray continuum. The shirt is usually white, or a solid color. In the necktie a guy gets to assert his personality, and to be emotionally and artistically expressive.
I think in the final analysis the necktie has no utilitarian purpose, but is communicative, and expressive.
UPDATE (8/21/07): There is a utilitarian purpose to ties that I thought of, or actually recollected. Back in the 70s I used to shop at the Pierre Cardin and YSL stores at the Watergate. I couldn’t make it into their suits, but I could manage the shirts and ties. The lady at the Cardin store once said to me that that the cravat was intended to hide the ugly buttons on a man’s shirt. Cardin hid the buttons by having a piece of the shirt that overlaid the buttons, and provided a neat front.