DON JUAN - At the Arena Stage through May 6.

Discovering a later period that fits Moliere's exquisite depictions of self-indulgence and hypocrisy in 17th-century France isn't really all that hard.

His Don Juan's philosophy, that you only have one life to live and should spend it pleasing No. 1, is no unknown even in our era; nor is Don Juan's impersonation of those who keep smugly invoking God.

But Liviu Ciulei, the Romanian director who put "Hamlet" into the 19th century for Arena Stage last year to modernize it while staying within a time of clear social stratification, has put Arena's "Don Juan" there, too.

What a shame that is. Fooling with "Hamlet" is an acceptionable theatrical occupation because there are always Elizabethan-style productions around, but Moliere's genius is not attempted as often in this country. One cannot be assured of seeing this play in its period glory, with the kind of memorably witty and stylized Moliere production Arena was doing 20 years ago.

The only justification here is the set designer's. Ming Cho Lee created a glass-floored terrace for Don Juan's apartment, under which can be glimpsed the fine furniture of another fashionable room.The lower section later serves as the echoing mausoleum in which the Commander lies in sculptured splendor. Even if modern audiences weren't starved for scenery from a diet of bare stages and symbolic steps, this set would produce the gasps it got at the preview.

But the dull black costumes representing turn-of-the-century evening clothes and servants' livery are a handicap to the actors' madcap antics, and having a gramophone on which Don Juan keeps playing "Parlezmoi d'amour" ought to punishable by a Moliere Defense Society. Even if it were funny, the Playwright does not need such gimmicks to brighten his comedy.

Richard Bauer, in the delicious role of Sganarelle, Don Juan's valet, whose moral outrage stops short of endangering his job and who represents both human striving and its failure, does have the Moliere comic spirit, matching physical farce with verbal nimbleness.

But Stanley Anderson's Don Juan does not. This is a character whose sensual and intellectual attributes should not only dazzle and conquer moral conventions but undermine philosophy and faith. Anderson, with his Bing Crosby nonchalance, seems no threat on any of these fronts. He becomes a modern person who doesn't defy morals, but simply ignores them.

It is just well that this version cuts Don Juan's final realization of his damnation. Hell had to go, one feels, because it didn't fit in with the updated production.