I use it very sparingly. If you want to know what people are down-voting just click the points next to their name and it will bring you to a screen that shows the points they got from up voted arguments, added arguments, as well as points lost by down-voting other arguments, and it will even tell you what debate it happened in. For example if you click the 3053 next to my name it will show you.

I think I only began to use it a few weeks ago, but lately I've down voted frequentlier and frequentlier.

Yes, I've used it but it's rare for me to do so. I only use it if I see what I think is an injustice... someone is unfairly (IMO) down voting someone else for no reason or maybe if I'm drunk or something.

Im new to this! :) But i have been playing around and yes i have used the down vote button! I thought thats what it was for? If someone says something off the wall that is not correct and has no proof.. Or if someone is entirely rude to someone elses response for like no reason?? I did see others put that they would like the person who down votes them to explain! I do believe this would be nice as i too would like to know why someone down votes me.. So, i feel from now on if i have the need to down vote someone else to atleast give an explanation??

ok i tried it and it worked- I guess I just don't get the POINT behind why it is even there to begin with

Yes I use it and I use it many times a day and i up vote them back again. LOLZ