> We don't grant copyrights to give authors a kind of royalty-based pension for their old age and their heirs.

"We" is doing a lot of work here. I realize that it's basically impossible for an entire population to have coherent motivations, but I support copyright because I think artists have the right to control what happens with their work and to sell it if they can. I believe that this right extends, like all rights, until the end of the author's life. I don't really care one bit about encouraging the production of new works.

> until the end of the author's life.

which is too long, and also too short - what about authors who wrote finished their book on their deathbed? Then their rights are shorter than someone young - an unfair discrimination.

That's why age should be irrelevant. Copyright is useful, and should be granted. However, current copyright grants last far too long - age plus some years beyond. Not to mention corporations lobbying to increase the length right as some copyrights for some works are about to enter public domain.

Therefore, copyright should be granted for a single period and end - like patents. 20 years seems to be a good middle ground, but i could hear arguments for slightly longer or shorter.

How about "We the people", as stated in the Constitution? The Constitution itself defines the purpose of copyright, and it is not the purpose you state.