While not following the whole debate, Liberator, while there I do believe that a child should have a father figure growing up, I don't believe that a child when properly raised by it's mother will be more prone to violence than one with both parents. They may have other developmental problems, but as long as the mother is actually, you know, doing her job as a parent, then I feel that in many cases the child may develop quite well, having to learn to cope with the hardship of a single parent household and making them a stronger person.
That being said, I will repeat my sentiment that a child should have a father figure in their lives, just as they should have a mother figure. One without the other is always hard for the child.