We've been having a little trouble around here lately with the words "I'm sorry". Whenever my boys do something wrong or hurt someone, I ask them to say sorry. Ryan has a stubborn streak, but he will generally say sorry and then move on. Lucas, however, takes stubborn to a whole new level.
Now that Lucas is almost 4 I feel like he's mature enough to understand the general sense of being sorry. I don't think he can mentally put himself in someone else's shoes and ponder how they may feel. But I do think he can understand that saying sorry helps to make things better, and then prompts an "I forgive you". (We try to always offer forgiveness after one of our children has been in trouble, once they apologize).
As an example, Lucas and I had a faceoff yesterday for almost two hours. He had hurt Ryan and then hit me repeatedly when I went to put him in a timeout. After he had calmed down a little bit he refused to apologize. He knew that was all he needed to do to be forgiven and come out and play. But he kept shouting "NO NEVER! I WON'T SAY SORRY". I must admit, after an hour of this I wanted to give up. But I didn't....and finally just before the 2 hour mark of tantruming he ran up to me and gave me a hug and said sorry.
Ugh nobody ever said this parenting thing was easy!