PeteEU,
Genocide is an extraordinary human-engineered catastrophe. It is unusual, infrequent, and of a magnitude that is far beyond the scale of most of the atrocities one witnesses in conflict--civil and international. Most civil wars, even with their atrocities and war crimes, do not constitute genocide.
In Iraq, the Sunni-Shia civil violence does not rise to a genocide. Although there has been an effort to "cleanse" neighborhoods, the effort does not amount to a deliberate pursuit of the partial or whole extermination of a people.
Ideally, the United Nations Security Council should be able to rely upon contributions from member states to intervene to thwart genocide. Yet, bureaucratic inertia, emphasis on differences in national interests, and even bias inhibit the effective functioning of that important international organ. The General Assembly is in even worse shape.
In the end, if one argues, as is stated in the subject heading of this post, "I really don't care about Darfur," and also expresses opposition to any kind of intervention to thwart genocide, then one's view translates into "I don't care about the Jewish people in Nazi Germany" or "I don't care about the Cambodians at the hands of the Khmer Rouge," etc. That's a severe position to take.
Would those taking such positions really have been willing to allow Hitler a free hand to carry out his Final Solution?
Quite frankly, I highly doubt it. For all the arguments made against intervention in cases of genocide, I find it difficult to believe that more than a handful of people, if they had the authority to make a difference, would remain unyielding in the face of imminent deliberate efforts by an armed group or revolutionary movement to initiate a widespread bloodbath aimed at trying to exterminate a people.
Indeed, even as he opposed additional assistance to Cambodia in 1975, U.S. Senator Jacob Javits finally cast the tie-breaking vote in the Senate Foreign Relations Committee in favor of a compromise solution (which failed later on in the whole Congress). In stepping away from his formerly-held position for a complete cut-off in assistance, Javits explained, "I don't want to be the one who gave Cambodia the last push to a bloodbath." In my opinion, even those who are now stridently arguing against intervention to stop genocide would likely make the same choice, if they were confronted with having to make a decision in similar circumstances.
Of course, human nature being what it is and humanity's tendency to forget the past, perhaps I am overly optimistic in expecting that people will truly remember genocide's horrors and retain the determination to oppose it. If so, genocide will more than likely resurface again in the future. For now, though, I'll hold to my more optimistic position that enough people will care enough to reduce future prospects of genocide.