Last season in Paris if you needed one item to help you cope with the incoming look in fashion, it was the shawl. If you wore a big shawl you could get away with almost anything you already had in your closet.

Now that Washington women are into buying and wearing shawls as fast as they can be found, Paris is into something else entirely. This year's answer to the shawl is the vest. Wear it over almost anything and you are on your way to one of the currently popular looks in the French ready-to-wear collections now being shown for spring.

In fact, chic young women in Paric who shop at the boutiques in Les Halles or Place des Victoires or on the Marche St. Honore, are already wearing these oversized, mannish vests, in corduroy, wool, heavy cotton, leather or knit.

The big giveaway for the American in Paris this season is her shawl. (Also not being worn much in Paris these days is anything with ruffles, turtleneck sweaters, or challis dresses, all popular at this moment in the United States.)

To be sure, the new vest bears no resemblance to the vests in our closets, left over from our three-piece suits. The new ones are huge and man-sized, unlined and totally shapeless. The sweatery versions are a chunky textured knit, or big grandpa sweaters. But others come in every imaginable fabric. They are the sister to another very popular look on the streets, that is also in the collections here and in Milan - the huge mannish jacket that is being worn with full skirts, big sweaters or tapered pants and high heels. Like the vest, the big jacket is shapeless, and often unlined so it hangs very loose. The big vest is often worn under these jackets with an oversized shirt.

The oversized vest has shown up in many of the collections that led off last week's ready-to-wear collections here. At France Andrevie, one of the current "hot" collections, the unlined vest in linen or leather was often the outer layer and shortest layer over dresses and tunics, all equally oversized.

Christian Aujard pairs the vest over one of the numerous big tent dresses that have shown up this week, such as his design at near right. Franck Olivier's loose vest, far right, goes over a full-sleved blouse and big skirt. Lison Bonfils makes a summer sweater of the vest, done in a lacy pointelle knit and Gaston Jaunet makes one worn with very square-cut camp shorts and very full culottes.