Disclaimer: These are some informal thoughts of mine on the subject, and should not be mistaken for a meticulously researched and comprehensive essay. I make no claims at being comprehensive here; this is a collection of miscellaneous thoughts and titles that occur to me when I think of "ethics and SF." Depending on the feedback I get, I may write more on this in the future.
Science fiction is the natural home of discussion of ethics. As I noted in a newspaper interview last year, one of the main concerns of science fiction (SF) is "ultimate issues." Among them are the fate of man, the fate of the universe, the ideal society, etc. A. Bertram Chandler used to say he loved writing SF novels because it gave him room enough to kick around ideas and see if they yelp. This is an apt description of the genre, for it provides a chance to do things "in the laboratory" with (theoretically) no harm to the real world -- you can destroy the universe, tear societies apart, postulate any form of God you wish, then do it all over again. I don't want to put all of SF in certain eras in a box, but it is fair to say that one of the dominant themes of the 1930's and 1940's in SF was technology. A typical story, especially early in the period, showed a person coming up with a strange invention and then showing the effects of the invention. Ethical issues in this era often touched on the appropriate use of technology.
In the 1950's, sociological SF was all the rage, and the ethics of societies and such were prominent. One of the key works of the time was Pohl & Kornbluth's Merchants of Space, which postulated the use of prisoners as organ banks -- a prediction that is apparently now coming true in China.
The 1960's was a time of civil rights struggles, and much SF of the period was concerned with this. Cordwainer Smith, in his Instrumentality stories (The Rediscovery of Man and Norstrilia), took Pohl and Kornbluth a step further, in having a prison planet ("A Planet Called Shayol") on which condemned prisoners were used to grow NEW parts for harvesting. Smith also poignantly addressed civil rights in these stories with his tales of the Underpeople, genetically manipulated animals who were the downtrodden in society, performing menial tasks and having no rights. In his structure of the society on the planet Norstrilia, Smith dealt with the question of how to make the best use of limited resources, how to avoid population explosions when you have people who are de facto immortal, how to prevent a society from letting wealth go to its head, etc. The more I look at Smith, the more I see that all of his work is suffused with a profound interest in all sorts of ethical issues.
As we move to the present, we see that Political Correctness has gripped a number of authors. Suzette H. Elgin's Judas Rose series posits the usual evil Christian theocracy suppressing women, and deals with a number of issues relating to how women deal with a theocracy that resembles Islam more than Christianity. The ethics in these books basically boils down to: in general only women are ethical, but an exception is made for Amerindian males because they are Politically Correct.
David Brin's work is also infused with Political Correctness. The Postman starts out with a fascinating premise -- that re-building the postal system would be one of the most constructive things to do after a major disaster, and that seeing postal deliver resume would cause a lot of warm and fuzzy feelings to resonate with people. The climax of the book, however, has a group of women sacrifice themselves, thus setting a moral example that everyone is awed by -- in the real world, such a sacrifice might be less than efficacious. Earth is a novel in which the ethics revolve around whether one believes the neo-pagan concept of Gaia is a more trustworthy source of ethics than humankind.
The idea of a next step up in evolution has always been popular. A.E. Van Vogt's Slan dealt with this in the 1940's. More recently, Nancy Kress' Beggars in Spain series deals with the idea of a group of humans who have evolved upwards, and addresses the ethics of what obligations they have to the rest of humankind, and what demands humankind has the right to make of them. A weakness in these books is that Kress' superhumans always know best and apparently rarely have inventions go awry.
Treatment of inferiors by their betters is taken a step further in many "first encounter" stories where humans meet aliens. A common theme is the alien invasion story, where aliens have to make ethical decisions re how to treat US. In the comic book field, the current title Mars Attacks addresses this issue frequently. When Heaven Fell by William Barton is one of the best alien invasion books of recent years, and deals with the ethical decisions of how to live under a harsh alien regime and still maintain one's dignity and humanity.
Patricia Anthony's Brother Termite has aliens visiting Earth ostensibly to share technology and culture. In point of fact, they are on the edge of self-destruction, and the only way out the aliens see involves ethical decisions that we humans would feel are not in our best interests. Octavia Butler has some books also dealing with the topic of how much to let aliens mess with us. Arthur C. Clarke's Childhood's End is perhaps the classic here, though I would consider it a much darker book than most of its supporters would.
On the flip side, how would aliens fare if we are the ones who invade? C.S. Lewis was very concerned with this issue, and was quite pessimistic about it. His Space trilogy (Out of the Silent Planet, Perelandra, That Hideous Strength) deals with some of the fears Lewis had about how we would treat aliens.
Much of the fiction published in Astounding/Analog magazine during the 1950's and 1960's covers the topic of how first contact with aliens should be handled. Murray Leinster's "First Contact" (1940's) is one of the all-time classics of this genre.
Brian Aldiss' Helliconia trilogy deals with the fear by humans that we would destroy an alien decision if we come in contact with it; he explores how things might turn out if we just set up observation satellites and watched...for thousands of years.
Part of the ethics re aliens is figuring out whether they are "equal" to us, i.e., whether they count as sentient. The classic books on these lines are H. Beam Piper's Little Fuzzy series. A. Bertram Chandler covered this topic in a number of his short stories, particularly one in which some humans accidently get captured and treated as pets by an alien race.
A major variation on this has been the issue of at what point do machines/robots become intelligent enough that they should be considered sentient/human? Isaac Asimov's robot stories often center around this. Robert A. Heinlein's The Moon is a Harsh Mistress is one of the best on this issue. Also recommended: David Gerrold's When Harlie Was One, Martin Caidin's The God Machine, and Jack Williamson's books on the Humanoids.
Some ethical situations are set up by scarcity of resources. In outer space this is a constant problem, because usually one needs things like oxygen and food for survival, and such things do not naturally occur in space. Tom Godwin's "The Cold Equations" is a classic story covering this, wherein a stowaway is found on a spaceship where there is not enough food or oxygen on board to support both the stowaway and the crew. A. Bertram Chandler's "Giantkiller" pits sentient rats against humans on board an interstellar grain transport.
In terms of medical ethics, the science fiction of James White (particularly The Genocidal Healer) is the best work that has been done. Much of Murray Leinster's work also covers medical ethics.
Greg Bear's Blood Music addresses the ethical issues of genetic manipulation gone wild.
Military SF is often written more as an exercise in strategy and tactics than in the ethical decisions one must make in real combat. A major exception is David Feintuch's Nicholas Seafort books (Midshipman's Hope, etc.). Seafort (a man I would not myself care to serve under) is constantly placed in tight corners where he must make ethical decisions that affect the lives of others. In some cases, he must send people to their deaths if he is to save many, many lives. In other cases, he must deliberately break his word of honor in order to save his ship, and (unlike many heroes in literature) he is haunted by this breach of his oath.
Richard C. Meredith's We All Died At Breakaway Station is a military SF book with some good material on the ethics of self-sacrifice.
How should a society be ethically and morally organized? One of the more off-the-wall answers to this question is in Philip K. Dick's Clans of the Alphane Moon, where the lunatics take over the asylum -- literally.
David Gerrold takes the "how honest are you with yourself?" question to its ultimate conclusions in The Man Who Folded Himself, wherein a time traveler meets himself not just once but, ah, many times.
The ethics of telepathy are covered in Dan Morgan and John Kippax's New Minds books. Robert Silverberg's Dying Inside is also good on this subject.
In many respects, our society could be described as a post-Christian one, particularly as postmodernism increases its hold on intellectual thought in our universities. As a result of this, much fiction (and SF is no exception) is concerned with trying to set up a moral compass in a universe in which God (and God-given moral principles) does not exist. Even more so, with postmodernism, you have writers fumbling around for how to make moral and ethical decisions in a world in which right and wrong and truth have become meaningless terms. Likewise a number of writers work within a framework of assuming moral and ethical relativism, but are not seeing the implications of following such principles to their logical conclusions.
James Blish's A Case of Conscience has some good stuff in it re ethical decisions from a Christian framework.
On television, by far the best example of ethics in action is Babylon 5. It is a complex, 5-year long story in which three-dimensional characters are faced with important ethical decisions that have no easy answers. The creator of the series has stated that the central theme of Babylon 5 is about people making choices and taking responsibility for those choices.
In fantasy, four works stick out to me as being pre-eminent re ethics. Stephen Donaldson's Chronicles of Thomas Covenant series is an exercise in frustration -- you spend volume after volume reading about a character who could make a difference but who is frozen in indecision as the world collapses around him. It' s one of those cheery works where you feel like slitting your wrists afterwards so you will feel better.
J.R.R. Tolkien's Lord of the Rings is at the opposite end of the scale -- it's about people who are not afraid to make decisions and who then have to pay the price of those decisions. Gandalf the wizard is faced with the temptation of the One Ring -- if he has it, he knows he will have ultimate power, but he turns it down because he knows it will also ultimately corrupt him. Frodo, who carries the One Ring all the way to Mount Doom, is constantly faced with the temptations and uses of power. Elrond sends the One Ring to its destruction, though he knows its destruction will mean the end for his own powers. The various bad guys are living out the consequences of past choices to Do The Wrong Thing.
C.S. Lewis' The Screwtape Letters, structured as a series of correspondence between two demons, is a highly entertaining tour of how ethics works within an explicitly Christian framework. It is particularly concerned with how temptations and greed can affect one's moral compass.
G.K. Chesterton's The Man Who Was Thursday sets up one of the classic ethical Mexican standoffs of all time in literature. A police investigator and an anarchist are pitted against one another, both bound by their oaths of honor not to reveal the others' secrets. When reading this book, be sure to note the book's subtitle and, if possible, purchase one of the editions that contains the one-page afterward by Chesterton (which he wrote shortly before his death, explaining important aspects of the novel).