THE SATURDAY EVENING POST award for best speech at the Republican convention has got to go to Rep. Guy Vander Jagt, the keynote speaker from the Netherlands by way of Hoboken. It seems, at least this year, that everyone who is anybody in the Republican Party is a first-generation success story and all of them seem to be clinging to the same American dream their fathers came here to pursue. Guy Vander Jagt is no exception.

"Sixty-six years ago this month," he told the convention, "my father stood on the docks of Hoboken. He stood there in clothes that were patched and tattered, but they were the very best he had because he had just immigrated here from the Netherlands. No man has ever been poorer in material possessions or richer in dreams than that little 14-year-old Dutch lad standing there in wooden shoes on the docks of Hoboken."

But that little Dutch lad, it turned out, "was dreaming some mighty big dreams. He dreamed that if he worked long and hard and saved he might one day own his own transportation." And then, maybe his own home, and then maybe he just might have some children, and they might go on to get high school diplomas and maybe, just maybe, a college degree. But there was no way, said Guy Vander Jagt, that his daddy could have ever believed one of his children might be elected to Congress and give the keynote speech at the Republican convention -- in just one generation.

Now let us pause here and say hip, hip, hooray for the Vander Jagt family. Theirs is no small accomplishment and it's nice to know that there are still some people who can make it and if they should cling a trifle tightly to the American dream, well, that can be understood.

But the keynote speaker at a political convention doesn't just speak for himself. He is chosen by the party leadership to deliver a rousing , bellringing, inspirational message that tells the world what his party plans to deliver. He's supposed to set a tone. If a keynote speech isn't riveting, it's still worthwhile hearing. It's supposed to tell you about the way the people running the party think, about the way they see the world around them. The trouble with Guy Vander Jagt is that he sounded more life Professor Harold Hill telling his audience in The Music Man what was wrong with River City than a Republican Party spokesman telling us what was wrong with America, but no matter. It's not the way he spoke that was most distressing, but what he said.

"It is our historic opportunity," he said, "as a united party to be the chosen instrument by which and through which the American people reach out to change the direction we're traveling to restore the American dream, to make America work again, to make America great again. . . .

"Here in Detroit, where the stilled assembly lines, the closed factories and the jobless workers proclaim the bankruptcy of Jimmy Carter and his policies, we feel the anguish of our people -- that unemployed auto worker who has to try to explain to his little daughter why the long-promised birthday bicycle isn't there because daddy doesn't have a job anymore."

After a plug for the Republican tax cut, he goes on: "I say that it is the height of irresponsibility and callousness to deliberately plunge one million more children into the heartache of saying, 'Daddy doesn't have a job anymore.'"

Daddy doesn't have a job anymore.

Daddy?

Isn't someone missing from the Republican picture?

Of course there is. Things have changed since Guy Vander Jagt's daddy stood on the docks at Hoboken and things have changed since Dwight D. Eisenhower and Barry Goldwater stood on the Republican platform. And while the Republicans would be the first to tell us these changes are causing no end of trouble, it is a fact that some of these changes are, quite simply, immutable.

It is a fact of American life that Daddy isn't the only one buying bicycles and that Daddy isn't the only one getting thrown out of work, and that if there were 1,057,000 men laid off in the first six months of 1980, there were also 451,000 women.

It is a fact that the number of American women who work has doubled over the past 20 years to 41 million now, and that this year, 3,337,000 of them are unemployed. Women, in other words, are unemployed at about the same rate as men. And it is a fact that the rule on those United Auto Worker assembly lines is the last person hired is the first person fired and that this, generally, is a rule that hits women workers hardest.

And it is a fact that the American family in which Mommy stays home and takes care of the children while Daddy goes off to work represents only a fraction of American families now. For better or worse, more than half of the American women work, and they too are earning bicycle money. Times have changed, and women have changed and, even if Guy Vander Jagt and the Republican Party don't realize it yet, the American family has changed.

American women have their own stake in the American dream.