A hearing on the death penalty today provided a relative rarity in the Maryland General Assembly - a wide-ranging theoretical discussion of a major issue and its moral implications.

The death penalty was alternately characterized as a desperately needed deterrent to premeditated murder, and as a reprehensible and inhuman response by a callous society at a hearing today before the Senate Judicial Proceedings Committee.

The range of opinions over the death penalty can almost be defined by several verbal exchanges among state senators during today's 3 1/2-hour hearing.

The first took place between Sen. John C. Coolahan (D-Baltimore County), sponsor of one of several bills that would re-institute the death penalty in Maryland, and Sen. Margaret C. Schweinhaut (D-Montgomery), an opponent of the death penalty.

"I am fully aware that there are people in the legislature and elsewhere who do not believe in the death penalty," said Coolahan. "I believe very honestly that the death penalty can act as a deterrent to crime . . . I believe that retaliation by society for a heinous crime is an appropriate response."

"I've heard many times that jurors will not convict" accused murderers if they are aware they might be sending the defendant to death, said Mrs. Schweinhaut.

"I don't buy that," replied Coolahan. "I think quite frankly that the vast majority of the people of this state want the death penalty back on the books."

"What bothers me is, I wonder if we can be right in what we do if the process is so repugnant that we can't stand to see what we do," said Mrs. Schweinhaut. "I couldn't stand to watch someone executed. If we can't stand to see what we do, how can it be right?"

"There were an abundance of volunteers in Utah" for the execution of convicted murderer Gart Gilmore, noted Coolahan. "While it may be repugnant to many, at the same time there will be that many or more" who approve of capital punishment.

State Attorney General Francis B. Burch, who wrote the Mandel administration's death penalty proposal, said the bill would cover only a limited number of crimes, which are "basically the kind of crimes you would not expect a wealthy person to commit."

But Burch denied that the law would discriminate against poor people and added that "the public defender system of the state of Maryland is more than adequate" to protect the rights of the poor.

Another debate came during the testimony of Sen. Thomas P. O'Reilly (D-Prince George's), a sponsor of death penalty legislation in recent sessions, who said today he has changed his mind and now prefers life imprisonment for murderers.

"I have reasoned that capital punishment is not the answer," said O'Reilly. "I see it as being simply barbaric. It's unreasonable, it's a disgrace . . . To think that the rapist or the murderer will have such a sophisticated view to sit down and reflect. 'If I commit a murder, it's a more serious sentence,' is just fallacious reasoning . . . It's ludicrous."

"How about the ones we have on the record," demanded Sen. Jerome Connell (D-Anne Arundel), "where the armed robber, in no danger himself, turns around and looks the guy in the eye, and shoots him down like a dog"

O'Reilly responded that he thinks life in prison would be enough of a punishment.

"Do you believe that caging an individual for the rest of his life, with no hope of anything, is more merciful than the death penalty?" queried Connell.

"Yes, because I believe that life is important, O'Reilly replied softly. "We should have a greater respect for life than that guy did . . . What will we gain by killing the person? What do we accomplish? We just sa wa circus in Utah. Do you want Maryland to be another circus?

Maryland's death penalty law was invalidated by a 1972 Supreme Court ruling. Following guidelines suggested by the Court in 1974, Maryland reinstituted the death penalty in 1975, making it mandatory upon conviction for any of eight categories of murder. Last year, a ninth category was added. A decision by the Supreme Court later last year, however, invalidated the new law because it did not allow judges and juries any discretion.

The laws proposed this year would adopt the two-level procedure in death penalty cases most recently recommended by the Court. A first trial would determine guilt or innocence. In case of a conviction, a second hearing would be held to determine whether the death penalty should be imposed.