So, the people of this community have by design recreated the accident that split Captain Kirk into good/bad parts in the classic first season Star Trek episode, "The Enemy Within." In this story, Jessica goes through the procedure and becomes two warring parts, while Logan and REM endeavor to put her back together and bring justice to the community.
In this story of a "city where all are perfected," there's one individual worth noting: a character named Rama 2, played by a very young (and very beautiful) Kim Cattrall. Seems she's actually a cast-out living among the Positives. When she went through the processor as a child, Rama's positive side died...leaving only her cast-out side. But ever since then, there's been a deception. Rama has been living as the consort of the Patron, the community leader (played by William Smith) and hiding her "negative" nature. Because she has been successful, Rama's presence proves that the processing procedure doesn't really work. A little good and a little evil resides in each split part of the citizenry...and so the attempt to separate these essential human qualities is foolhardy. That fact makes Logan and REM's task easier, repairing the society.
The "Enemy Within" plotline and the use of easily-recognizable Star Trek sound effects for the processor machine only serve to reveal what a pervasive influence Gene Roddenberry's creation had on the rest of science fiction TV in the 1970s. Logan's Run's "Half Life" is, like "The Innocent," diverting and entertaining enough, yet still ultimately rather derivative. At least - finally -there's a whole society on display here, not just a little community with one citizen. That's a bonus, I guess.
It is kind of neat that Logan and REM (and sometimes Jessica) feel absolutely free to interfere in any society they run across. You see, these guys have no Non-Interference Prime Directive, so if their lives are threatened, they can meddle. I thought this clarity would be refreshing, but actually I miss the Star Trek rule. There, Captain Kirk had to justify his interference; and find ways around acting selfishly or rashly. Here, there's one layer less of drama because Logan can engineer any societal changes he deems necessary, and he often does so with the business end of his Sandman-issue weapon. Somehow, that makes things too easy...