PG seems to be advocating a pragmatic approach, based on the difficulty of enforcement. Goods can be excludable or non-excludable. Excludable goods are anything

PG seems to be advocating a pragmatic approach, based on the difficulty of enforcement. Goods can be excludable or non-excludable. Excludable goods are anything that can be effectively locked down (like most physical goods, or movie tickets). Non-excludable goods can't (like air, fish in the sea, and IP). You can make a non-excludable good excludable by creating laws (like Carbon Taxes or IP laws), but it's not always practical. But he kind of misses the other half - rivalry. Goods can also be rivalrous or non-rivalrous. Ideas are non-rivalrous as you don't lose anything (except a competitive advantage) if other people also have it. In fact, IP may be the opposite to rivalrous (which is a rare enough thing to not have a name, though I like the name "network goods"), because it's worth more if everyone has it. If more people can speak a language, it's more useful to everyone. The Lord of the Rings is more interesting if you can talk to your friends about it. While there's a good reason to try to make common goods (rivalrous but non-excludable) goods more excludable (by introducing laws which prevent over-exploitation), it's perverse to make non-rivalrous excludable. You don't tax breathing if there's plenty of air. The main reason you want to make a public (non-rivalrous non-excludable) good more excludable is to incentize its creation (another reason might be because it's judged to be a "de-merit" (bad) good - such as a porn or a method of manufacturing weapons). But since IP is an input to creating IP, there's very good reasons why you want to make copyright and patents expire in a short time - bringing down the cost of creating new IP may outweigh the lost incentive. Also, the anti-rivalrous nature of IP may even encourage people to make more, simply because it's so useful have more people using it - Linus got his own private kernel debugged and extended at a lower cost by sharing it.