Dynasties are supposed to rise, then fall. But there must be a lot of folks in the National Football League who have given up on the Dallas Cowboys. They may never be brought down.

Clint Murchison started the NFL franchise here in 1960. He hired Tex Schramm as his general manager. Then he hired Tom Landry, a defensive coach for the New York Giants who had been an all-pro defensive back, as his head coach.

For 23 years the three have worked together, very successfully: 16 trips to the playoffs in the last 17 seasons, 10 National Football Conference title games in the 13 last years, five Super Bowls, two world championships, the NFL's best record since 1960 (202-115-6) and a 20-13 record in postseason games.

When the Cowboys finished with an 8-6 record in 1974 and failed to make the playoffs, the city was not so much disappointed as stunned.

"Our goal is always to win the world championship," said running back Ron Springs. "Other teams' goals might just be to go to the playoffs. There are always winning teams--Philadelphia, Frisco, the Redskins--and we're going to have our letdowns, but we always have the winning attitude."

In their first year, the Cowboys were 0-11-1. But they opened the 1961 season with a 27-24 victory over the Pittsburgh Steelers and Landry began a winning tradition. Five years later, the Cowboys were second only to Vince Lombardi's Green Bay Packers in the NFL, and they have been among the top teams ever since.

With the help of Gil Brandt, the player personnel director, Schramm, who was given the title of team president in 1966, and Landry have built their teams largely from the college drafts.

Often their choices were well-publicized college standouts: Bob Lilly, Lee Roy Jordan, Craig Morton, Randy White, Tony Dorsett.

Just as often, however, the Cowboys have made unlikely first-round draft choices that have provided star after star. In 1969, they drafted Yale running back Calvin Hill, and the next year completed the backfield by selecting Duane Thomas from West Texas State.

The Cowboys also have managed to exploit with uncanny skill the lower rounds of the draft, discovering Elizabeth City State tackle Jethro Pugh in the 11th round, Fort Valley State tackle Rayfield Wright in the seventh round and Oklahoma State running back Walt Garrison in the fifth.

Tackle John Dutton, whom the Cowboys obtained when they gave the Baltimore Colts their first two draft choices in 1980, is the only significant player on the roster who did not arrive through the draft.

Quarterback Danny White, linebacker Bob Breunig and defensive end Harvey Martin are all NFL standouts, and all third-round draft choices by Dallas.

"Tradition and the way we view the draft has a lot to do with our success," said Martin. "We had the chance to see the old guard on the way out--the Lillys, the Garrisons--and that's important."

White and Breunig credit the team's success to the only man to coach the Cowboys.

"I attribute it all to Tom Landry," said White. "More than anybody else, he has an ability to pick a team up. He will set goals, breaking the schedule up into three- or four-game segments. If we fall behind he'll come in with quality control and things inevitably straighten out."

"It's all Coach Landry," said Breunig. "He's a very intense worker, a dedicated worker, but he's under control. He has a perspective on what he's doing. My relationship with him is businesslike. He likes it that way because he has to make tough decisions whether to cut players or who to start."

As Dick Vermeil's recent departure from the Philadelphia Eagles for reasons of emotional exhaustion suggests, Landry's distanced, professional posture could be a reason for his longevity in the job and the team's success.

Players from Pete Gent to Butch Johnson have grumbled about Landry. And the press has had almost as much fun with the "computerized coach" as it has with the collected speeches of Bum Phillips and Casey Stengel. But Landry's results are sufficient answer to his critics.

"You know, we think of Coach Landry as so stern, saying why were you late for practice and so on," said Martin. "But it all contributes to concentration and winning."

"Football can't be played without discipline," said Drew Pearson. "Sometimes little rules can get annoying to a 32-year-old man, but it's a necessary way to give you a sense of responsibility."

Pearson also gives credit to Brandt for discovering talent and to Schramm for building and protecting the team's image.

"We have a whole organization," Pearson said. "That's the reason we're on top. When Philadelphia won, it was Vermeil. With San Francisco it was (Bill) Walsh, he was a genius. But when we win year after year, it's not Coach Landry, it's not any one player, it's the organization as a whole."

Landry, for his part, also is quick to credit the team's executives. "We have a good organization that feed us players," he said. "And when people make it with the Dallas Cowboys they don't worry too much about their jobs.

"We develop players. Sometimes it takes two, three years. (Offensive guard) Kurt Petersen was a linebacker and a defensive tackle in college, but he has come along. You pick them and have patience."

Not everyone is quite so sure why the Cowboys have been so good for so long.

Safety Benny Barnes came to the Cowboys 11 years ago as a free agent from Stanford. He shakes his head when asked about the Cowboys' success.

"For me to be in eight championship games is just unbelievable," he said. "We're there every year. Why is just a question I can't answer."