Voting is great but without the ability to down vote bad ideas still accumulate and they don't get pushed back by the community.

So to be clear...
vote up (we currently have this)
vote down (requested here)

I hope this gets voted up haha :)

ps - yes I completely understand that the good ideas get more votes. However there are thousands of ideas and without the communities ability to push back the ideas keep accumulating votes and thus stay relevant.

e.g. An idea that has been live for a year may only have 5 votes which means that it is not valid.

However if that same idea had 2005 up votes AND 2000 down votes it would mean half the community want it and thus it would be valid.

It may only be a slight change but has huge engagement implications. We would now be engaged with the ideas we don't think are right as well as the ones we do.

Cheers
Hamish