It is singularly ironic that the most frequent compliment paid to Paramount's film ''The Lost Weekend'' by its eager and well-wishing friends is that it represents ''daring'' on the part of its producers in tackling an uncommon theme. The irony is, in the first place, that discussion of a psychopathic ''drunk'' should be regarded as socially taboo. That notion, supported by old sanctions, is an obsolete reference in itself. But the second and more immediate irony is that a film should be hailed as bold simply because it is candid in attacking a serious adult theme.

Why shouldn't a film be frank and forthright in coming to realistic grips - as this one does beyond question - with a subject of deep concern? Why shouldn't producers go searching, as a matter of creative course, for subjects which serve an honest purpose in revealing mankind to man? The normal assumption of the critic should be that films are here to convey adult dramatic entertainment - or emotional stimulation, if you wish. And whenever a film such as this one stands up to that job, it is vaguely an insult to its caliber to label it ''daring.'' What's that mean?

100 Proof

In this particular instance it doesn't mean nay more than that ''The Lost Weekend'' is sharp and truthful in exposing a chronic ''drunk.'' It measures a single alcoholic by the yardstick of modern medicine and the recognized psychological tensions of our aggressive society. To be sure, our motion pictures, as other art forms, have not be inclined to take such a forward, scientific viewpoint on excessive drinking in the past. Most of the lushes in movies have been bleary-eyed comic characters or occasional drab and wasteful victims of a mystifying ''curse of drink.'' (Has anyone stopped to remember that D.W. Griffith's last film was a tear jerker called ''The Struggle,'' in which Hal Skelly played a heavy problem ''drunk''?) But, for all its scientific understanding, the only thing ''daring'' about this film is the fact that it offers the public a morbidly shocking show.

However, that is scarcely audacious, considering the public's taste - and also considering the competence with which the film was made. For Charles Brackett and Billy Wilder, its joint writers and producer and director, respectively, have fashioned as fine a character study as we have had on the screen in some time. They have taken the Charles R. Jackson novel of the same title, which was quite a vivid book, and have made it even more vivid through the exercise of genuine cinema art. And they have treated a dreary human problem in a way that is sure to teach and fascinate.

Long Short

With a coldly observant camera they have followed a dipsomaniac through the torments and humiliations of a terrible four-day ''binge.'' They have carefully explained his ''illness'' - a frustrated ambition to write (which is not a sufficient reason for such persistent bottle fighting as we see, but it serves at least, to make it evident that all ''dipsos'' have some hidden gnawing pain). And then they have grimly documented every episode in his ugly, shameless bout with his own self-consuming frustration to the bitter and agonizing end. Well, not the end, precisely there is a hopeful solution contrived for a climax involving the efforts of a patient and loyal girl. But none of the torturing experiences of the defeatist writer are spared, from his panhandling [word missing] a bartender to a frightful night in the Bellevue ''alchy'' ward.

The same cinematic realism that distinguished their ''Double Indemnity'' has been applied by Brackett and Wilder in imagining this tale. Much of the candid graphic action was photographed here in New York, the locale of the hero's ''bender,'' with a sharp emphasis of visual details. And through Ray Milland they have captured such a portrait of pathos and chagrin as wrings the heart of the beholder.

One serious objection to this picture has been raised, however. One writer says (in the Quarterly Journal of Studies on Alcohol) that it will do great harm, particularly in supporting the ''rationalizations'' of actual chronic ''drunks.'' It could 'impede the sensible, rational solution of the problems of alcohol.''

Somehow this objection reminds us of Abe Lincoln's famous remark to those who demanded the removal of General Grant because he drank. ''Can you tell me the brand he drinks?'' said Lincoln. ''I'd like to send all of my generals a supply.''