> Intellectual property isn't real property, though

Do you mean intellectually property isn't really property, or do you mean intellectually property doesn't consist of estates in land (“real property”.) The latter is obviously true, but hard to see it's relevance; the former is false. IP is no less property than any other form of intangible personal property.

Intellectual property has many differences with other forms of property. The differences consist of two main properties that tangible property has which intellectual property does not: scarcity and exclusivity.

- Ideas are not scarce goods. They are for all intents and purposes infinite. - Ideas cannot be exclusive. Two people can have the same idea at the same time.

There are only so many apples available, restricted by sunlight and water and nutrients and such. If I hold an apple, another person can't also hold that apple at the same time.

That's why IP isn't property.

Sure it is, it is a completely different thing. The only way I could see thoughts and concepts being property, is if human law defines reality. But it does not, it just tries it's best to model an idealized version of reality. This really starts to become apparent where legal English diverges from dictionary or common English.

> The only way I could see thoughts and concepts being property, is if human law defines reality.

IP isn't thoughts and concepts, it's expressions and concrete applications, and “property” is a legal relationship; human laws don't define reality, but they do define legal relationships.