Well practically , I can't find the need to have a common language around the world because language serves as the "identity" of one person or country. If we will just have ONE language around the globe , how we will be able to distinguish the nationality of each and everyone ? Language represents the culture of every country so why change it to one common language ? Besides , i believe that  we will still be able to communicate to others even if we have differ language as long as we listen to them with our heart and be more comprehensive with each other's opinion . The key to good communication is with our actions not with language .