Basic Information
Values Dissonance occurs when the morality of a character or culture in-story (whether historical, fictional or game plot) conflicts with the morality of the audience (or players). This can turn out to be something of a challenge for some players and audiences and may need to be handled with care - whilst in an ideal world bowlderisation would be severely punished too much dissonance may make a work more trouble than it is worth for a given audience.
It is also possible to have dissonance between cultures in-story - indeed it reduces the congruent reality of a setting if there is not some dissonance as well as some common ground between any two given cultures. How much of each will normally depend on geographic difference (and species if appropriate). In some cases lack of dissonance may be noteworthy.
Another important role of values dissonance is in the creation of meaningful antagonists for your characters (or meaningful PCs if your players like to run villains and antiheros). Although it's a pretty standard trope for fantasy villains to be self consciously "Evil" … and even for "evil" to be a cause in its own right … this is a little too dissonant to be credible1. In reality - and in congruent settings - very few people are likely to consider themselves "evil" but will appear so to others due to values dissonance. If a worldbuilder or GM takes the time to create realistic motivations for his antagonists, the resulting story is liable to be much more playable.
(More to come)
