MAGIC - Avalon 1, AMC Carrollton 6, Loehman's Plaza, White Flint.

All the old tricks of the psychological thriller, an art form in which murders is considered a natural instinct requiring only the most perfunctory motivation, are brought out for Joseph E. Levine's "Magic."

Levine's reputation for producing hits for educated audiences - such as "Carnal Knowledge," "The Lion in Winter," "The Graduate" and "Marriage Italian-Style" - and films that moved right up into the cinema-buff category lead one to expect something more sophisticated. The "Magic" opening scene, in which an elderly Merlin called Merlin snoozes fitfully while waiting for his protege to return from the stage, has the intellectual crackle of Robertson Davies' books about the thinking magician with the symbolic sleights of hand.

With bewildering speed, Corky, the young failure of a magician, turns into a celebrity ventirloquist and unaccountably goes berserk. Anthony Hopkins can do a pale blue-eyed look of madness as well as any actor, but gives no hint as to what's driving him.

All right. These are standard tricks from the conventional madman-on-the-loose thriller, but not outstandingly bad tricks.

Here is the dirty trick.

Having become a ventriloquist, Corky turns schizophrenic. This is not an original gimmick, either. But the rules of any drama, magic or otherwise, then demand that each of the two characters, the ventriloquist and the dummy he manipulates, personify something different, if only different sides of the same personality.

In this case, they dress alike. They talk to each other. Their careers are inextricably tied together. But there is no valid difference between them, except that the dummy seems slightly brighter, but the ventriloquist gets the girl. And this is not enough to justify splitting the character in two.

The ventriloquist is overcome with a fashionable attack of nostalgia, and seeks out his high-school dream girl - played in such a pedestrian fashion by Ann-Margret that his continued infatuation does seem a clue to his lack of judgment - while the dummy keeps alert to the present. The ventriloquist has homicidal attacks, but requires the dummy to explain how they may be carried out. Still this is not a matter of a psychological split, but of two heads being used to show how one maniac functions.

Thus the thrills of a conventional horror story have been blown up so pretentiously that they're no more scary than balloon monsters.