This proposed "filter" promotes exactly the kind of behavior it claims to prevent, and there are already methods in place to reduce the presence of "stupidity" when we need to.
So wait, let's stop and think of what we see as "stupid" on the Internet. From what I've gathered from the consensus of people on Slashdot, stupid is anything you find in the comments on digg.com. In general, these comments tend to have elitist qualities with chauvanistic implications like "my penis is bigger than yours because of arbitrary qualifications x1, x2, ..., xn". In other words, they give you the sense you're in a junior high classroom. Now, this filter turns the former statement into "my penis is bigger than yours because i'm more intelligent than you are". It's just as elitist, and just as invalid. There are people you might call stupid, but they happen to be CONSIDERATE and they are at least willing to learn, or to change.
We already have means for dealing with this as well. In closed forums, we ban the offending individual. In open forums, since they're open and all, we ignore them.
I really fail to see the necessity of any sort of filter, unless it's to impose your own, elitist regime on everyone else.