Yes I said when I joined this site, that I would never block anyone because I was always interested in alternate opinion. But I forgot that a lot of alternate opinion can be mindless and boring, and you can just have too much dross blocking the pages. I have therefore blocked someone at last, not for disagreement or quality but just because of quantity. (Probably the same person. )

Click on the person's profile. Scroll down. On the lower right is an option to "Block user." You can choose to block him/her for one day, one month, three months, six months or forever.

you can also go select their profile, scroll down and there is a Block user option on the right side.

Click the gear icon in the upper right. Then click the right-most tab and enter the name of the person you want blocked.