One of the big debates over the past few years in copyright economics is whether unauthorized uses of a work (say, a clip from a film put up on YouTube) actually enhance the value of the work used. I think that the landmark Sony case mandates such an inquiry in fair use cases, and that we have better ways of estimating such effects than we once did (given advances in environmental economics).
However, sometimes I despair of social science’s ability to tease out all the complex effects involved here. Consider this article on c0-0petition between the establishment fashion press and fashion blogs. The hobby blogs are sometimes vicious and unrestrained, but offer a refreshingly independent perspective; one, for instance, “warn[s] her fans against donning head-to-toe logo-a-go-go attire.” The article suggests that the hobbyists may not merely disparage, but also entirely displace, existing publications…upon whose content they often base their work.
However, many are optimistic that the blogs ultimately complement the MSM of fashion; one commenter says “blogs and mainstream magazines can exist in tandem,” and “freelance fashion writer Maggie Alderson agrees that ‘They aren’t going to snuff out the fashion press.'”
I like focusing the inquiry on whether the blogs will eliminate the MSM of fashion, rather than whether they reduce or increase their revenues. It strikes me that copyright has much to learn from the limits of misappropriation law, where a necessary element of the claim is that the unauthorized user threaten the existence of the plaintiff. That’s a much easier question than whether an unauthorized use substitutes for authorized (paid) uses, or whether the substitution effect outweighs the complementarity effect.