mousthief,

-> You failed to note the distinction, implicit in what I wrote, between means and ends.

-> You are falling back on the copyright-maximalist trick of replying to questions about the proper scope and duration of copyright by simply repeating arguments for why there should be some copyright rather than no copyright, leaving the question of "how much ?" unanswered.

-> The Constitution states that Congress has the power "to promote the progress of science and useful arts". This means enlarging the public domain. If there remains any doubt, the same clause goes on to state that the monopolies granted under this power must be for limited times.

T.