That's the title of a recent article by psychiatrist Ronald Pies at Psychiatric Times (free login). As Dr. Pies states:
There are some crimes so heinous, they may simply be beyond the human capacity to forgive: genocide, murder, and rape come quickly to mind. Gangdev (following Mahoney et al, 2005) defines forgiveness as the "...releasing or foregoing of bitterness and vengeance by a victim toward the perpetrator of an offence, while acknowledging the seriousness of the wrong."5 (italics added) Thus, none of us--other than the surviving victims--is in a position to forgive the Tucson shooter for the wounding or killing of innocent bystanders.
I take a somewhat different view. The question is not whether human beings have the CAPACITY to forgive a heinous crime like Loughner's. The question is whether there is any REASON for forgiveness. So far as I am aware (although I will keep an open mind as additional evidence may come in), there isn't.
I guarantee you, however, that the defense will try to portray Loughner as the victim. The real victims will turn out to be an inconvenient footnote to Loughner's sob story, whatever in it the defense psychiatrists are able to fabricate.
It does bother me that he appears to have been exhibiting all these signs of mental illness and there is no evidence that anyone in his family sought treatment for him. That's just plain bizarre.