[ckannan90]

That's such a strange thing to say. When artists create their work, do they rank them by the estimated number of years of their legacy, and discard the ones that fall outside of the copyrightable timeframe? I mean, are you implying there are artists out there who aren't creating works because they feel that this one is definitely a "life+75" piece of work, and so what's the point if all I get is life+70?

[hammock]

Imagine a copyright that lasts only one day. Would you ever write something to appeal to an international audience? There wouldn't be time enough to translate it.

Imagine someone lives beneath a volcano and knows that at some point an eruption will destroy his house such that he no longer extracts economic benefit from it. Do you think that the way he builds his house (e.g. using straw, or stone) will differ based on whether the eruptions come every 10 years or every 100?

If artists are motivated by the economic incentive afforded by copyright, then the level of that motivation is variable based on the length of copyright.

[SEMW]

> If artists are motivated by the economic incentive afforded by copyright, then the level of that motivation is variable based on the length of copyright.

While that's undeniably true, I think the objection is to your leap from observing that motivation significantly increases with term length at term = 1 day, to concluding it's still significantly increasing at term = life+70yrs.

Economic incentive can be measured and modelled, and while there isn't that much research into this, there is some. One Cambridge study (Pollock [2007]) found that the optimum length of copyright term is ~14 years (any longer and the economic benefits of works going into the public domain outweigh further increases in incentive to produce). Now, yes, economics models should be taken with a large grain of salt (especially ones when it's unfeasible to test their predictions). But it's a start, and certainly there don't seem to be any econ studies supporting a length anywhere near life+70 or longer.

[nano111]

Are you saying that home builders and engineers should get paid royalties for as long as the house stands?

[eru]

No, that's the wrong analogy. Hammock's comment applied to housebuilding would be that new houses would fetch lower prices (and thus there would be less incentive to build them), if after a few years your house would cease to be your property and become a publicly owned good.