A lot of commenters are concerned that they would lose the part of their culture that is in their language. But isn't only a small part of one's culture in the language? Culture includes history, traditions, food, celebrations, arts, beliefs, ethics, and so on. With a worldwide common language (or a common 2nd language) you could instantly communicate with anyone, anywhere, and get exposed to every other cultural detail. You gain understanding, lose your ignorance, build connections.

I think there is already a world language developing because of the internet. It is a 'good enough' English. Grammer and spelling don't need to be perfect to communicate. I've met many people in the US who speak 'some English' and get along fine.

It would be kind of boring, it would be like we all look the same.  Languages make culture, people and jobs more interesting besides there must be a good reason why we have such variety of language and dialect.

Yes, Easton, it would be wonderful if the 7,000,000,000 people currently living in the world spoke the same language.

I think that it would definitely lead to a more peaceful world.

I also think that it would great if there were just one culture.

In my country (the United States), there are many languages and many cultures. This situation often leads to unpleasant situations.

Maybe I am wrong, but I think the happiest countries are those where at least 90% of the people speak the same language, believe in the same religion, and share the same cultural values.

There will be many people who lose their jobs....

If in all the world we spoke only a language, the world would be very boring....If it happened, shouldn't exist , for example , the italki's community where anyone of us look to improve and learn a new language.