The goal of nofollow is to reduce spam. It does that by excluding links from search engine ranking calculations. Google suggests that this be used by blogging software to flag links for trackbacks and in comments on blogs: a worthwhile trade-off if it saves us from spam. However, some people my use nofollow on links pointing to sites with which they disagree.
This is a dangerous abuse of the tool, for it attacks the connections that make the Web valuable. Furthermore, it encourages one of the other threats to the Web and the blogosphere: parochialism. It becomes easier and easier to converse only with people of similar interests and opinions. The links that cross-cut interests and convictions are valuable because they tie us into a larger public conversation.
Even distasteful opinions should be exposed to the world. Take a recent column on the Ayn Rand Institute site, which included claims like the following: “The United States government, however, should not give any money to help the tsunami victims. Why? Because the money is not the government’s to give.” The Institute has since retracted the original article. The fact that we can deplore the removal of the original text makes it clear how important it is for this kind of material to be accessible.
A link created by the author of a page flags its target as relevant to the page. The problem with spam is that it is irrelevant: it is all noise, no signal. Nofollow is an appropriate way to filter out the noise; it should not be used to attack the signal. The vote-links proposal offers a better way to deal with disagreement. Just as the blogosphere deplores posts that are silently updated, we should expect that nofollow never be applied to relevant links deliberately created by the author of a page.
In Tim Bray’s case, I am of two minds: spammers so flagrantly violate the social contract that they deserve no consideration. But the whole point of this exercise is that the Web is more important than the spammers. Making such fine distinctions sets a risky precedent.