In any crowd of cheerful, positive-thinking citizens, there is at least one eternal optimist who longs to believe that somewhere, somehow there must be a form of discrimination that is "fair," or even "good" for women.

If such a person exists among you and is not busy clapping hands for Tinkerbell, allow me to introduce him or her to the friendly neighborhood insurance industry.

For two days last week, at congressional hearings on a bill to ban discrimination in insurance and annuities, we heard testimony showing that women are paying more and/or getting less from their insurance than men.

In the pension business, for example, men and women often make equal payments to buy an annuity, but women get less-than- equal monthly payments back.

The industry, for its part, didn't deny that it offers separate plans for men and women. Rather, it held aloft actuarial tables, as if writ by the great Statistician in the Sky. Anatomy is destiny, they declared. Women live longer, they receive more monthly payments and so they must pay more.

Insurers have made similar arguments in terms of medical and disability policies since this issue was first raised. They are just following numbers: if women cost more, they must pay more. What's fair is fair.

But fair isn't always easy to assess. At the crux of this controversy is the fact that insurers choose to group people and then make predictions about the behavior of that group. They do not call this discrimination; they call it "risk categorization."

There is, of course, nothing sacrosanct about the groups themselves. Until fairly recently, they grouped people by races, and charged blacks more for life insurance than longer-lived whites. They stopped when it became socially unacceptable. They have never grouped people by religion, although Mormons and Seventh Day Adventists live longer than others.

Now women are claiming that being grouped by sex is equally discriminatory, arbitrary and harmful to them as individuals. The "average" woman, for example, may have a longer life expectacy than the "average" man. But out of every 100 women and 100 men, 84 of each sex will die in the same years. As Mary Gray, a math professor at American University and president of the Women's Equity Action League, testified on a similar Senate bill: "I have one life expectancy as an American. I have a longer expectancy as a woman, a shorter life expectancy as someone in a stress-filled position, a longer life expectancy as a nonsmoker, a shorter life expectancy as one who is overweight. There is no reason why our sex should be singled out."

The all too chivalrous rebuttal from the insurance industry now is that women aren't really suffering under this two-track system. Indeed, they insist, equality will cost women dearly. But whenever someone protests that equality will hurt women, watch out.

There are two areas today in which women pay less than men. Young female drivers under the age of 24 are generally charged less than young male drivers for auto insurance. Women generally pay 10 to 20 percent lower premiums for life insurance.

The auto insurance difference is based on the fact that young men get into more car accidents than young women. Indeed, men get into more accidents at all ages, but for some curious reason, the segregated rates usually end at age 25.

Here again, the insurers group people by sex rather than by their driving records or how many miles they travel. The real discrimination is against good young male drivers in favor of bad young female drivers. Ironically, this bias against men is the only one that's been corrected. A handful of states have now passed laws ending sex discrimination for young drivers.

As for life insurance, women usually do pay between 10 and 20 percent less for the same amount of coverage. This can be lower than the difference between companies, and is often wiped out by discounts, such as that for nonsmokers.

But even if you include these so-called advantages, the bottom line is simple. The "break" that women get in auto and life insurance is piddling. They pay dearly for their sex when it comes to medical coverage, disability coverage and pensions.

In one reasonable analysis compiled by the National Oragnization for Women from the industry's own figures, being a woman can cost $15,732 in insurance over a lifetime. That, on anyone's tables, is a real "risk category."

Copyright (c) 1983, The Boston Globe Newspaper Company