It is a good idea to have someone proofread your paper because they can see the little mistakes that you may not have noticed while writing your paper. A different set of eyes can offer a more in depth look at your paper than you reviewing your own paper over and over again. Another person will be able to tell you if your paper makes sense and flows. Every person thinks in a different way, the way you think may not articulate to your audience. If another person reads what you wrote, they may be able to show you where you can make changes in order to ensure your paper makes sense to everyone who reads it, not just you yourself.