Star Trek: The Next Generation, in many of its episodes, portrays and examines many social issues of the present day is such a way that the audience can come away with a new, non-emotional, understanding of the issues. Such portrayals and examinations are the provenance of science fiction.
An example of a social issue discussion appears in episode #117, The Outcast.
In this episode the Starship Enterprise encounters the J'naii, an androgenous
race for whom the concept of gender is so foreign that they find the concept
repugnant and deviant (even though they do reproduce sexually). Those members
of their race who demonstrate tendencies toward one gender or another are labeled
deviant and perverted and must be "cured". Commander Riker, an officer
on the Enterprise, finds one J'naii, Soren, very attractive, and it responds
to his attention by realizing that it prefers being female to sexless. When
her society discovers her desires it demands that she be cured of her perversion.
Soren points out how similar she and those like her are to "normal"
J'naii, and cries out, "What makes you think you can dictate to us how
we love one another!" (ST:NG #117) Nonetheless, she is put through a brainwashing
that convinces her that having gender is wrong, and she ends up claiming she
is much happier as a "normal" J'naii, although her formerly sparkling
personality now appears to be one of no personality at all. (ST:NG #117)
The parallels of the episode are clear to some attitudes about homosexuality
in American society today. A society with no gender that considers people who
announce they have a gender to be perverted is the same as a society with gender
(male with female) that considers people that have a different view of gender
(male with male, female with female) to be perverted. The J'naii's insistence
that their "deviants" can be cured parallels programs in America that
say they can "reprogram" or "cure" homosexuality. (Hadfield)
The Star Trek episode subtly condemns not only anti-homosexual attitudes (as
exemplified by the J'naii's attitudes), but the idea of "curing" genetically
determined behaviors and desires. (Khytam) However, because the discussion is
done in a science fiction setting, the discussion is less likely to cause an
emotional response to the issue in the audience than if the same issues were
presented in a standard drama. Science fiction places its ideas in places and/or
times that are separated from the audience's, allowing the audience to believe
that the discussion isn't about them and thus doesn't trigger emotional responses.
(Asimov) This allows the audience to have an intellectual appreciation of the
discussion, unhindered by emotion. In such cases, the audience can begin thinking
and arrive at reasoned, logical conclusions about the issue under discussion.
In the case of The Outcast, it allows the audience to examine their own
attitudes and prejudices about homosexuality.
Many ST:NG episodes dealt with social issues that allow the audience to think
and arrive at reasoned conclusions, including what is the meaning of human,
what makes a parent a parent, what is love, when and how does one become an
adult, and many others. Because of this approach to storytelling, ST:NG demonstrates
how science fiction can affect an audience.