Wiesel defines indifference as a "strange and unnatural state." What is your definition? How can indifference be unnatural?in reference to "The Perils of Indifference"
I would define indifference as a state in which you do not care about something -- you do not care about what happens in a given situation or to a given person.
I think that you could say that indifference is unnatural because (you can argue) people are naturally inclined to care about things. I think that people naturally want to take sides and "root" for one side or another in just about all conflicts.
However, Wiesel is saying that we can only be indifferent if we do not think that other people truly are people.