Mercy seems wimpy, passive, even wrong somehow. Let one guy get away with it and the rest will try, seems to be the theory. But mercy is the counterpoint to justice. It is the reminder that despite all our laws and lawyers there are times to give it up and just let go. It is a reminder that a society cannot live by rules alone.
Pardons are legislated acts of mercy.
And as such, they don't really make sense to our justice-oriented minds. Sure, we can understand pardons to heal the country or even to help out a relative. But we want to know why when pardons are conferred on people we don't see as worthy. Mercy is deeply rooted in our Judeo-Christian heritage. As our society becomes more secularized, such a transcendent concept becomes harder to understand.