In my last post, I suggested that broken links, although typically perceived to be a problem, might also serve as an interesting historical source if properly mined. Today I'd like to address a related topic: the fact that the content of websites changes even while the URL remains the same. In this blog, for example, I've made a lot of references to articles in the constantly changing, user-contributed Wikipedia. This means that the article on concordances that I cited on 29 Jan 2006 has changed since I cited it ... 16 times, in fact.
The reason that I know how many times the article has changed is that Wikipedia has a 'history' page for each article that keeps track of revisions and allows the user to compare selected versions of the article. The most recent change to the article on concordances (as of this post) was to fix a misspelling of the word 'frequently'.
A sophisticated Wikipedia user consults the history page before reading the article, much the way that EH Carr recommended that we study the historian before reading his or her work. It soon becomes clear that some articles offer a relatively stable interpretation, while others are subject to ceaseless revision. Although similar processes can be observed in more traditional historical discourse, the rapidity with which Wikipedia changes, and its extensive and automatic philological apparatus make it a natural laboratory for experiments in digital history. Mills Kelly, for example, has blogged about his experiences trying to change the article on the fate of the Donner Party, widely believed to have resorted to cannibalism when snow bound in the Sierra Nevada in 1846. Mills revised Wikipedia to reflect new work in historical archaeology which calls this interpretation into question, and then watched as other people revised his changes toward a temporary consensus. Mills has also assigned the task of writing Wikipedia entries and watching them be revised to his grad students. [For more on his experiments, see What's for Dinner? (Cont'd 1) (Cont'd 2) and Whither Wiki?]
As with other forms of new media, we need to be teaching young historians how to read wikis critically and how to write them effectively. We should also be aware of the new resources that they provide for computational historiography. To take a single example, look at the "history flow visualization" created by Martin Wattenberg and Fernanda Viégas, which maps the revisions of the Wikipedia article on evolution.
So is all of this completely new? Not really. As any work is reinterpreted over time, citations to that work will change in meaning, too. Traditional historical works age along with the literature that they cite. As a physical analog, we might think of refraction: a wave bending when it enters a new medium. There's a good description of the phenomenon at Wikipedia ... at least there is right now.
Tags: bibliography | citation | data mining | digital history | historiography | public history | Wikipedia