Defense and aerospace stocks continued a two-day decline yesterday that some analysts attributed to the announcement by Sen. John G. Tower (R-Tex.) that he would not seek reelection.

Lockheed Corp. fell 2 5/8 to 104 on the New York Stock Exchange. General Dynamics was off 1 5/8 at 46. E-Systems was down 7/8 at 34 3/4, Northrop was down 4 1/2 to 82 1/4, and McDonnell Douglas was off 1/2 at 47. Raytheon fell 5/8 to 47 3/4 and Rockwell International fell 1 1/8 to 27 1/4.

However, other analysts said that the impact of Tower's resignation was exaggerated, noting that Tower would probably be succeeded as chairman of the Senate Armed Services Committee by either Barry Goldwater (R-Ariz.) or, if Democrats regain control of the Senate, by Henry Jackson (D-Wash.). Both are supporters of a strong defense budget.

Bigger factors in the selloff of defense and aerospace stocks, according to several analysts, included anticipated defense spending cuts during the appropriations process, the natural end of a cycle of high defense stock prices, the uncertainty surrounding the 1984 elections in general and recovery in some other areas of the economy where earnings have heretofore been dismal compared with defense.

"Basically, the Tower announcement hit people over the head and focused the people who have discretion over money" on the other factors, said David Smith, an analyst with Sanford C. Bernstein & Co.

Defense company earnings have been good and will continue to be strong in the next several years because of commitments already made through the appropriations process, he noted. Offsetting that expectation, however, is bad news on the political front, including expected defense budget cutting, attacks on wasteful defense spending and the elections, he said.

Smith said he thought the reaction to Tower's prospective resignation was "a knee-jerk reaction, and when people come around they will see those earnings are going to be strong," he said.

United Press International quoted Drexel Burham Lambert analyst Laurence Lytton, who said Tower's announcement had substantial impact because "the main protagonist of defense spending is stepping down. He also said that Tower's lame-duck status would weaken the administration on defense issues.

"I think it's an exaggeration" to attribute the decline to the news of Tower's departure from the Senate, said Alan Benasuli, an analyst for Drexel Burnham.

"I think it was something that triggered other factors," he said, citing other political considerations such as the election year approaching and the anticipated clamor for defense cuts. He also said that the decline was partly due to a nervous market and a "tendency to take profits in things that have worked out."

"Even if the Democrats take hold of the Senate, Scoop Jackson is no dove," he said. "It's just the little thing that triggered everything else."