This page considers how restrictive one should be about the sharing and modification of one’s content.
gwern, for instance, likes CC0: “I believe the public domain license reduces FUD and dead-weight loss, encourages copying (LOCKSS), gives back (however little) to Free Software/Free Content, and costs me nothing.”
In a footnote he elaborates:
[Public domain] increases economic efficiency through - if nothing else - making works easier to find. Tim O’Reilly says that “Obscurity is a far greater threat to authors and creative artists than piracy.” If that is so, then that means that difficulty of finding works reduces the welfare of artists and consumers, because both forgo a beneficial trade (the artist loses any revenue and the consumer loses any enjoyment). Even small increases in inconvenience make big differences.
Some sites like the Subject Wiki use CC-BY-SA, and others use CC-BY. Any stricter license prevents remixing, not that there is anything wrong with that.
Richard Stallman says:
In my view, nonfree licenses that permit sharing are ok for works of art/entertainment, or that present some party’s viewpoint (such as this article itself). Those works aren’t meant for doing a practical job, so the argument about the users’ control does not apply. Thus, I do not object if they are published with the CC-BY-NC-ND license, which allows only noncommercial redistribution of exact copies.
CC-BY versus public domain
What is the difference between CC-BY and CC0, in terms of what one should choose? One argument that they don’t make much difference is that any respectable person would give attribution anyway—so even given the full privilege of public domain works, one would still essentially use it like CC-BY. Another idea is that (like myself) most people won’t go after others even if their copyright (or copyleft) claims are ignored by other parties.