The Enterprise observes an experimental mining operation overseen by the ambitious Dr. Farallon (Ellen Bry) to decide whether her technological methods can be deployed in more widespread use in the Federation. Farallon has in her employ some advanced robotic tools she created, called "exocomps." When one of them inexplicably malfunctions, Data takes it back to the Enterprise for further diagnostic. He slowly comes to the conclusion that the exocomps may be alive.
Just what exactly is "alive"? Data has a conversation with Crusher that asks this very question, and the discussion ends probably the only way it can — inconclusively. As the episode notes, if you boil down the criteria of what living things generally do — exist, consume, attempt to survive, multiply — you could make the case that fire is "alive." But perhaps there must be something beyond that — a spark that transcends the qualifying definitions. I think ultimately what this episode is talking about is not simply life, but intelligence. The exocomps are learning machines rather than simple tools. But does being a somewhat more advanced robotic intelligence make them alive?
I'm of two minds on "The Quality of Life." On the one hand, it is in principle a pure example of the "seek out new life" mantra of the Star Trek ethos, and it is surely an episode whose underlying issues are fodder for much discussion and debate about the nature of life (artificial or otherwise) and our responsibilities to it.
On the other hand, by taking the argument as far as it does, the story threatens to collapse under its own moral conviction. A crisis arises, involving Picard and Geordi being trapped near deadly radiation, and the only way to save them is to send in the exocomps to make the necessary repairs, which will unfortunately result in their destruction. Data becomes the exocomps' advocate and locks out the transporter controls, barring the solution because he believes the rights of these possible life forms are not being considered. In effect, Data is willing to sacrifice the life of the captain and chief engineer on the hunch that these machines might comprise a rudimentary intelligence that may or may not rise to the level of sentience. That to me is taking things a shade too far into oh-come-on territory. (From a chain of command standpoint, Data's actions are probably worthy of a court-martial.)
The unintentional point the story almost seems to make is that Data is looking at this issue from such a coldly detached logical point of view (albeit from a uniquely personal perspective) that he doesn't even consider that the value of life is not simply about whether it exists, but what humans assign to it emotionally, in the form of relationships, attachments, and feelings. To put it another way: If you accidentally kill a deer with your car, you're not going to feel nearly as bad as if you kill a person, even one whom you don't know. Why? Because certain life is simply more important because of the value we assign to it. Now, where do you draw the line? Good question. But Data and "The Quality of Life" are not interested in drawing lines or designating the order of value. They want to treat all life equally, which means the exocomps have every right to live as Picard and Geordi, even if they may only be marginally sentient. For some reason, that to me seems slightly ridiculous. Maybe I'm just prejudiced against little robotic tools when instead I should be leading the charge in freeing Siri from her prison of iPhone servitude.
I also felt that Dr. Farallon was a little too obviously written as the story's (mild) villain, who at first comes across as annoying and obstinate, but learns the story's lesson by the end. (Ah, TNG's spirit of mutually arrived understanding.) Ultimately, a compromise solution is reached. That solution allows the story to walk away without compromising its ethics, while also saving Picard and Geordi. It's an interesting resolution to an interesting dilemma, but it doesn't force anyone to address the question of the difference between the value of life and the quality of it. That "The Quality of Life" is good at inspiring these sort of questions is to its credit, but consider me on the fence as to its effectiveness as drama.