Copyleft licenses are not "restrictive"

Copyleft licenses are not “restrictive” by Drew DeVault.

Copyleft is predicated on a deeper understanding of freedom in which freedom is a positive guarantee of rights.

Copyleft does not impose restrictions, but it does impose obligations. The obligations exist to guarantee rights to the users of the software – in other words, to ensure freedoms. In this respect copyleft licenses are _more free_than permissive licenses.

Copyleft licenses constrain these powers through additional obligations, and from these obligations greater freedoms emerge. Specifically, they oblige reciprocity.