There is a difference between a voluntary shrink-wrap license and
the Gnu copyleft; in the former, your acceptance of the terms must
precede your purchase, as evidenced by exchange of consideration.
That makes it a contract--and offer is made, accepted, and executed.
Stallman's software is free, and since no consideration is exchanged,
there can be no contract. He simply gives you information, then
issues a unilateral pronouncement about how you will use it--or even
what you may derive from it--whether you consent or not. And the
copyleft is (theoretically) binding even on those third parties who
come in contact with the information by perfectly legitimate means
without having examined any contractual terms. It is, for example,
legal for me to post source code for GCC anonymously to the net.
But then anyone who downloaded that anonymous post--and thereby
incurred real costs prior to examination of the contract--would be
bound by the copyleft nonetheless.
-- Lee Daniel Crocker <lee@piclab.com> <http://www.piclab.com/lcrocker.html> "All inventions or works of authorship original to me, herein and past, are placed irrevocably in the public domain, and may be used or modified for any purpose, without permission, attribution, or notification."--LDC