Follow-up to the previous post...
People always have been creating works inspried by another works. After all, the books, papers and blogs are just the other modes of communication, and in the everyday communication we do react at something the others say.
Before internet era, though, things were different in the sense of how references have been maintained. If you have been writing a book, you would quote your sources. They were, in principle, localizable. Everything that has been printed has a number of attributes with which it can be more or less unambigously identified: the title, year of being printed, the name of the printing house; later, the ISBN number which is not the ideal solution, but it's fair enough solution to live with.
Therefore, if you read the book and the author is quoting his and her sources, it was always theoretically possible to locate the sources and to find out what the work has been based upon. It was not always easy (suppose the quoted source existed in one exemplar, or was not quoted directly, etc), but it was doable.
Now, we have Internet, and everything is supposed to be stored there forever.
As I write it, Internet is full of derivative work.
Most of the articles have links to the other articles, which in their turn have links to yet another articles, and so on. It's world wide web, so it's normal.
And these links are in fact as firm as the gossamer threads. May be gossamer threads are even better. Ever seen not working links? (I bet any article which exists in the web for more than one a couple of years probably has them, either directly or indirectly).
I can't stop wondering what will become of all this in several dozen years or so. Will there be a big pile of everything, to which every article that has been around long enough would be assumed to go? If somebody in 20 years would want to trace how ideas were spreading via internet, will it be possible to do? Will these sites still exist, will they still be pointing at each other? How to understand what somebody is writing about if his or her references are gone? Unless there would be a searching engine which would have a knowledge about the evolution of internet - may be it will be one more use case for Google or for some other company - temporal data mining :)
A pessimistic scenario is that, notwithstanding Internet, blogging et cetera, everything below a certain level of importance will have the same chance of getting completely into oblivion as the derivative work of earlier generations - or even a bigger one. The letter which the 8-year-old Babylonian boy would scrabble on the calfskin existed as an object, and would continue existing until purposefully destroyed or until the skin crumbles (which would take many years). The blogs which are hosted on a certain site are obliterated completely if the site closes down and nobody takes care of the content. (Theoretically, information still can exist hidden in the hard drives, but how quickly will the old hard drives be disposed of?)
I hope we will dedicate enough work in the near future to prevent the web from losing its structure with time. Keeping the dependencies will be quite difficult part of it... I am very curious how this problem will be solved. If it will be solved.