Richard Stallman believes that the Golden Rule obliges him to give away
the software he finds to be useful. The law won't allow him to do this with
software copyrighted by others, so he and his associates write similar software
themselves and then give it away. Read Stallman's
"The GNU Manifesto" (http://www.gnu.ai.mit.edu/gnu/manifesto.html) and comment on Stallman's belief and practice.
Also see Stallman's "What Is Copyleft?" with link to the GNU General Public License,
and "Why
Software Should Not Have Owners"