If you write a blog, from time to time, people are going to write comments that you disagree with. Some of those comments will put forward a view apposed to yours, some of them will show you up for not knowing as much about a subject as you purported to and some of them will just be purely insulting. The question is, do you delete them?
Some bloggers I read delete comments that disagree with their point of view. They argue that they shouldn't have to pay for space in which someone disagrees with them. Well okay, that's a point of view, but it's a pretty naive one. If blogging is about the global conversation, how useful is it if you can only hear one side of the conversation? It is much better, in my view, to be the sort of blogger who leaves comments up no matter how much the commenter disagrees with them.