Q.My son is a fully developed 16-year-old. From time to time, our next-door neighbor visits us in our home, and my son walks around in his brief underwear.

My son feels there is nothing wrong with this, since he considers our neighbor almost part of our family. He can't see the difference between this and his very brief swimsuits, which he wears in and around the house during the summer.

My wife tends to agree with him that his opaque underwear is no different from the brief bathing suits that I wear working outside and around the house in summer. I see that similarity, but I still feel that there is a noticeable difference, and that it is wrong to wear underclothing in front of anyone other than the immediate family. A.A. Your wife and son are A. expressing a very common naivete and literal-mindedness when they deny the symbolic function of clothing, claiming that its only meaning is in how much territory it covers. Would you wear pajamas to the office, explaining that they cover as much as a business suit? Would your wife wear a strapless ball dress in the back yard, claiming that it exposes the same amount of skin as a bathing suit with cover-up sarong skirt?

Underwear indicates a state of extremely intimate undress. (For example, it would be indecent at a public beach, even if it covered more than a bathing suit would, and at a nude beach, it would be indecent where nudity would not be.) Miss Manners believes it to be proper only in bedrooms, but if nobody in your family is offended by seeing undershirts and slips at the dinner table, she will only ask that you keep the blinds drawn.

Wearing underwear in front of guests is an insult. Not only does it imply that the guest is not worth dressing for, but it suggests that a sexual relationship exists of a nature that does not require observing basic decencies.