Reversing a decision of two weeks ago, the Senate Rehabilitation and Social Services Committee voted 8 to 7 yesterday to change Virginia's method of execution from the electric chair to injections of lethal chemicals.

While proponents argue that the new method is more humane, some argued against the change on the basis that making the penalty more humane will lessen its function as a deterrent to crime. Others objected that a less shocking method of death would make it easier to impose the death penalty.

"I want {judges'} guts to be wrenched when they have to make that decision," said state Sen. Joseph V. Gartlan Jr. (D-Mount Vernon), a death penalty opponent who argued against the change. "If our society ceases to have trouble in imposing capital punishment, if we let ourselves gloss it over . . . we are embarking on a dangerous, dangerous road."

State Sen. Richard L. Saslaw (D-Springfield), supporting the change, countered that juries have "tremendous reservations" about the death penalty already and that using a more humane method would not make that decision easier or more difficult.

Sen. Frank W. Nolen (D-Augusta) opposed the change and said his real preference would be to have the criminal killed in the same way he took the life of his victim.