A creative person who composes music, writes a poem, play or book, or who paints a picture, etc. Is usually trying to make a living doing such things. Why should this person not be compensated for his/her work just as anyone else is who has a job in manufacturing, retail, teaching, caring for the sick, delivering mail or any other viable job? An artist cannot remain an artist if they have to spend their time earning a living by NOT doing their art. We should value these creative people by honoring their thought, imagination and hard work through compensating them each time we use, borrow or steal what they have produced.
If a mashup artist make the choice to use the intellectual property (IP) of someone else by sampling their music they should expect to pay for the use of that IP. After all the mashup artist is making money off the product of their efforts. Why shouldn't they expect to pay for the use of the IP they samples in making their product? If you want to get paid, you should expect to pay!
Should the artist being sampled offer up their music for public use, then that would be one thing. However, most artists (not always the singers, as we all know) work hard on their craft and have the right to be secure in ownership. When we 'sample' from literary works, it's generally called plagiarism.
It's only right that someone who uses even pieces of the work or protected intellectual property of someone else, pay the holders of those rights for their use. It could be argued that using sample is beneficial to future sales to the copyright holders, and the copyright holders have every right to allow such a thing if it's to their benefit, and set their own limitations, but if someone were using something that I had created, I would want to receive compensation.
As a mashup artist myself, It's hard to make money sometimes, and to have to pay the copyright holder and label money is pointless... And worthless because the artist (the one that's sampled) won't get much (if any) of the money, just look at Clyde Stubblefield He got no money from the sample of Funky Drummer. The royalty sample paying system is really flawed and worthless. Sample artists should definitely get Permission from the original artist, Just to make sure everything is cool. And it should definitely be easy to get permission. As for the argument that sampling is plagiarism, that's not true, because it's taking the work changing/improving it. And usually attributing or giving credit to the original artist... If anything it could benefit the original artist.
I support artists pursuing royalties that they're owed, because that's a viable way to make money in a tough field, but I think certain courtesies should be extended towards other artists like Girl Talk. Sampling and mash-ups allow for future art to be made and explored in different ways, and often brings more focus to the original source. Since only a portion of the copyrighted material is being used, I think that qualifying that use as "fair use" would be acceptable. Moreover, I think that current copyright law is outdated and has no idea how to fairly handle new concepts like sampling, and it is unfair to limit creativity based on these outdated laws.