What arguments would you present in order to make your case in favor of granting the right to vote to 18 year olds?

What argument would I present? I would present that everyone is equal and everyone has a voice if you had asked them to speak, people have different outlooks on being able to vote at 18 or 21.  But I don't know much about voting, I don't, and don't plan on, voting ever. S 

To prevent the population from overgrowing