As author Herman notes, there is no neutrality in the trauma of abuse.  The bystander — that’s you and me — cannot merely by-stand.  To do so is to choose, and the choice is for the abuser.  Evil only asks that we remain quiet and still.  Divert our eye and go on about our business.  This is at least part of the explanation for the blank stare and tic of discomfort we see in people when we talk to them about abuse.  Bystanders know that to acknowledge the reality of abuse and the plight of the victim is to force a choice between good and evil, right and wrong.  To stand with the victim on the other hand is to be required to take action, to pay a price, to take on a share of the victim’s burden.

Normally, the perpetrator wins as bystanders choose for him by turning away and just forgetting.  This is why an innocent person can be mugged or even murdered on a public street in front of witnesses, and no one does anything.

Trauma and Recovery: The aftermath of violence – from domestic abuse to political terror [*affiliate link]. Judith Herman, Basic Books: 1997].