“One of the fundamental ideas in free software circles is that
copyleft—the requirement that improvements to free software
remain free to the community—is essential (or at least very
important) for ensuring that the public good of free software
production isn’t co-opted and privatized
(“hijacking” I like to call it, in response to those
who dub copyright infringement “piracy”). However,
while this sounds good in theory, it’s a challenge to prove
it quantitatively.”