A PERSON can become preoccupied by one minor social issue, to the point where it fills the landscape and blots out all rival considerations, indeed all sense of proportion.
A fine clinical specimen was on display last week, in the form of a reader's letter headlined: ''Smoking's latest victims''.
The writer of this piece was one of those people who approves of smoking being banned in aeroplanes. Indeed I think without being unfair to him we can surmise that he approves of smoking being banned anywhere people can be persuaded to ban it.
Some people seek to ban smoking because it is dangerous to non-smokers, an understandable if scientifically fragile approach. This writer adopted the alternative approach, wishing to ban smoking because it is dangerous to smokers. This idea is scientifically impregnable, but open to the serious objection that people's selection of personal habits, hazardous or otherwise, is their own business.
So here we had David Norris of Wan Chai announcing that Melina Mercouri and John Candy had joined Humphrey Bogart, John Wayne and Bette Davis, ''legendary smokers who paid the ultimate price of their addiction''.
Actually this involves a dangerous assumption. ''Smoking-related'' diseases are those which are found more often in smokers than in non-smokers. Smokers as a group tend to die somewhat younger than non-smokers, and it is reasonable to infer that this is a consequence of their greater susceptibility to ''their'' diseases.