6 ideas
Intellectual property protection should be set at the level that balances the marginal benefit of inducing creation against the marginal cost of restricting access and raising future creators' input costs. Too little protection underproduces expressive and inventive works; too much raises the price of building on existing works and reduces total output.
Information goods are nonrival and nonexcludable: once created, they can be copied at near-zero marginal cost without depleting the original, so creators cannot easily recover fixed costs of creation. Legal exclusion rights exist to artificially restore excludability and let creators capture enough returns to justify the upfront expenditure.
Copyright protects only the specific expression of an idea, not the underlying idea itself, because granting monopoly over abstract ideas would impose enormous costs on subsequent creators who need those building blocks. This boundary keeps the cost of future creation low while still preserving incentives to produce particular works.
A trademark's economic function is to lower the cost consumers incur in identifying and verifying product quality, since a consistent mark lets buyers rely on past experience rather than reinvestigating each purchase. This reframes trademark law not as protecting sellers' goodwill for its own sake but as an information-economizing device that also incentivizes consistent quality.
When protection is too strong or its prospect of capture too lucrative, parties will overinvest in racing to create or claim protectable works, dissipating the social value through duplicative effort and premature production. The expected monopoly rent attracts resources up to the point where they roughly equal the rent, so excessive protection can destroy the very surplus it aims to generate.
Copyright terms should be finite because the present value of incentive from very distant future royalties is negligible, while the access and tracing costs of indefinite protection grow continuously. Perpetual protection would add almost nothing to creators' incentives but impose mounting costs on locating rights holders and licensing old works.