[jdietrich]

Dedicating a work to the public domain is legally very ambiguous and varies globally; Some jurisdictions do not allow a creator to relinquish their moral rights. Permissive licenses are simply a way of unambiguously stating that a work may be used freely. Permissive licenses also provide important protections to the author, as liability is not necessarily waived by relinquishing a claim to copyright.

As the Zen of Python says, explicit is better than implicit.