For:

I think the Internet provides us with a free space to express our own opinions. Everyone has the right to express himself online no matter what he says. For different people may have different ideas towards the same object, you should not judge other's opinions based on your own. At present, some people like to attack others' opinions on the forum. In my mind, you can reject others' opinions, but you can not regard them wrong.

Against:

One should be responsible for what he says

Nowadays, more and more people tend to express their own opinions on the Internet, especially in the forum. But I think, we should be responsible for what we say. If an opinion is wrong, it should be criticized by the public. Although everyone has the right to voice himself, he should be clear what he can say and what he can not. If his opinions are against the law or the basic moral, he should be criticized by people.