This is a crucial year for stout-hearted men. Either they will rise up and be done with the last great yoke of sartorial oppression or they will meekly succumb once more to senseless spending for the sake of conformity.

I refer, of course, to the necktie. For all of its acknowledged uselessness, this anachronism continues to survive despite the trend toward more practical dress that began in the 1960s. Even the younger generation's rebellion against the conventional clothing dictates has had little effect, mainly because too few fathers have joined their sons in rebellion.

But now there is a marvelous opportunity for Dad to rebel as well.

Seventh Avenue has decreed another of its mindless changes: The wide tie is out; the slim-Jims are back in. No matter that one has 10 or 20 -- or 100 -- of the old variety. They must be all discarded to update the properly attired gentleman's wardrobe.

All of this was brought home mercilessly to millions of men when they opened their Christmas presents. Behold, the newest crop of ties, almost all slims. Behold, too, the strategic salesmanship that produced this result. Shoppers found stores well stocked with prominently displayed slims -- clearly a calculated effort to give the new trend a big leap to the cash register.

The tactic will work if men are dumb enough to let it. And they may be that dumb.

On the other hand, the occasion provides an opening for males to finally muster their long dormant courage. They could simply resist the tide by refusing to wear what the market is dictating. That would be a minimum sensible step.The really sensible step, though, would be to stop wearing ties -- period.

The suggestion is not so radical as it seems. After all, women have pioneered in the liberation area: By turning to pantsuits and blue jeans and wearing what they please, they have established a firm new beachhead for fashion freedom. Why should men lag so timidly behind?

There area few encouraging signs. Some men, including executives, are beginning to show up at the office in casual, tieless garb. NBC's Jack Perkins no longer appears on television wearing ties. Dick Cavett frequently does his PBS interviews in turtleneck sweaters. (Another well-known correspondent, Edwin Newman, boldly tried to start a male liberation movement a decade ago when the big switch was made to wides by sticking to the then-fashionable narrow ties, but he got nowhere. Now, if the recycled style catches, he presumably will be judged to be a properly attired gentleman again).

Unfortunately, there have been setbacks, too. The Carter White House has been a particular disappointment. In contrast to the down-home informality that the Georgians brought to town two years ago, today's pesidential staff has been transformed into a conspicuous testament to tradition. Hamilton Jordan, who used to work in his shirt sleeves sans tie, now dresses -- in the words of a female colleague -- "as if he just came out of a New York bank."

The irony is that Jimmy Carter is an unstuffy man who can't wait to get into jeans and strip away his tie for nighttime work in his study. Because of this, Carter seems the ideal person to mobilize males for the march out of slavery.

White House aides might ponder the possibilities: The president wearing his nighttime uniform for daytime duty in the Oval Office, or perhaps delivering an evening address on television in the new sporty look. The benefits could be formidable -- rpoviding fresh proof that Carter indeed is serious about conquering inflation, and endearing him everlastingly to legions of males who would feel free at last.

It could, in fact, give the president the image of leadership and fearlessness he so desperately wants.