It has been noted elsewhere that a knowledge of informal logical fallacies can be used for (a) good or (b) evil. By this I mean that broadly speaking, a knowledge of logical fallacies can be used to: (a) detect false claims in argument in order to approach closer to truth; or to (b) make bigger, better and more sophisticated false claims in argument - in order to win an argument.
When a person shamelessly admits to engaging in argument in order to win an argument, then bad faith is not an issue, even when he or she uses a sophisticated knowledge of fallacies to wrong-foot an opponent. However, when the same person maintains that his or her motives are pure - in the service of truth alone, then bad faith is involved.
Bad Faith involves the adoption of a moral posture which is false. Other, more simple descriptors may be used to describe such a posture - "lying hypocrite" comes to mind - but bad faith is a term which is worthwhile advancing for its precision of meaning, and emotional coolness. (Calling someone a lying hypocrite can be provocative, whereas claiming that they are acting in bad faith may be, or ought to be more tolerable.)
Some examples to illustrate:
A journalist acts in bad faith when he or she claims to be reporting news - while in reality he or she creates news by provoking newsworthy incidents.
A social researcher acts in bad faith when he or she claims to be researching a topic in order to discover underlying reality - while in reality he or she discards and doesn't report results which don't support his or her cherished hypothesis.
A peace activist acts in bad faith when he or she expresses public anguish at the death of non-combatants while privately delighting in such casualties - as civilian deaths add weight to his or her rhetorical position on armed conflict.
Technorati Tagged - Fallacy, Skepticism.