I propose that spanking a child to achieve discipline is a failure of the adult. Parental attachment is one of the primary ways that children learn how to regulate their emotions. Emotional regulation is a cornerstone of empathy and behavior when interacting with others. I'm not making this stuff up off of the top of my head, this is the current state of research in child emotional and cognitive development. (See the Whole Brain Child and No Drama Discipline). The very core of child behavioral regulation is parental attachment, and mirroring. By spanking children, you directly undermine the emotional foundation that children use to achieve behavioral regulation. Spanking can get short-term results. Which is why parents use it (and other forms of violence, including deep psychological and physical abuse) to achieve the behavioral results they want. But those short-term results come at a consequence which is the long term emotional health and development of the child. Young children are often completely out of control of their emotional state and even their bodies. They are in the process of learning how to control themselves and regulate their brains. Spanking them disrupts this process and sends exactly the wrong signal. It teaches them that it is ok to hit, but it also teaches them that their emotional state is something to be feared, and that their bond with their parents is contingent. Stop spanking your kids.