English is just one language among the others
Languages are tied to the way humans think. English shouldn't be the world's lingua franca, as it shouldn't be French or German or any other language, in this regard. Languages are vectors of culture and boiling the world's culture down to one language is dangerous for the humanity. Just look at the yes group proponent : they are mostly English native speakers (Americans?) who have a warped view of the world and its very nature : diversity. I believe diversity is good and benefit all of us. "just about every culture in the world would be served well if they could communicate effectively with the united states of America." That sums up pretty much the dangerousness of a common language which would just benefit only one country over the others.