Stephan,

Well, the term has broad and narrow usages. You’re right that the narrow usage (popularized by the Free Software Foundation) only applies to licenses — like the GNU GPL and FDL, or the Creative Commons ShareAlike licenses — that are viral, i.e., which not only free the work itself for redistribution and derivative works, but also require anyone who produces a derivative work to also free it under the same terms.

I don’t have any particular view on what license you ought to use on Libertarian Papers. But I think that the “Attribution-ShareAlike” license would only be “less libertarian” than a plain “Attribution” license if the powers restricted by “ShareAlike” were legitimate powers for an author to exercise. But all ShareAlike requires is that authors distributing a derivative work not try to enforce copyright restrictions with respect to their own derivative work. If enforcing copyright restrictions is illibertarian (as you and I agree), then I reckon that forbidding licensees from enforcing them, isn’t.