'There won't always be a grown-up present' Should children fight back if they are being bullied?

Should we be teaching children that it is alright to fight back if they are being bullied?  Dr David Coleman, Clinical Psychologist, writing in the Irish Independent today argues: When it comes to a child being physically attacked, or physically bullied, my advice has always been to give that child permission to defend themselves. Hitting back shows the aggressor that a child is not an easy target.   What do you think?