How do I get my dad to let me get an iPhone 5?

The iPhone 5 is coming out soon, and my dad says I can't have one because I don't need it. He wants me to "sell" it to him about why I have to have it. I have the money and he says if I do get it he will not activate it. I am 13 with a non smartphone and an iPod touch. Yes, I know it is just the two combined, but I am so tired of having to be on wi-fi to get on the internet. If I tell him that he will thing I am stuck in a world of Facebook. My mom is all for it, and she is upgrading her iPhone 3g s to a 5. What should I tell my dad?