Suppose private property is justified. Take that as a datum.
Here is my question: What intuitions/settled judgments must a theory of property account for in order to be the right theory of property?
Here are a few jumbled thoughts:
The right theory of property will recognize the difference between external, physical objects that can, and those that cannot, be replaced without moral loss.
Consider the case of objects we possess for purely instrumental reasons. I have a screwdriver set at home. If you were to replace it with a just-as-good set of screwdrivers, I don't think there would be anything wrong with that (holding other things constant). Many things are like this. What we want is that the object serve some purpose, goal, project, or aim. If you can find a substitute that will do just as well, then we have no moral complaints with replacement.
I also have a watch that my grandfather gave me. You couldn't replace that with an object that is just as good, since no object, other than that one, will be just as good. I don't care that it tells time, that's not what matters to me when it comes to this watch. What matters is that my grandfather gave it to me. The originality of that object matters to me. Some people claim that this is true of Picassos and the Mona Lisa, of the Wayne Gretzky rookie card, and the pen that John Hancock used to sign that piece of paper Americans go crazy about.
I don't know what to call this exactly, but here is the upshot: The right theory of property should recognize that some ownership relations are more important than others. The right theory of property should be sensitive to the difference, for instance, between my first and only dollar, and your million-and-first dollar. Or, if we think that it shouldn't be sensitive to this, to the difference in moral weight between your owning your home and your owning your screwdriver. The latter matters less.
The right theory of property will be "scalar"--it will note and explain the fact that some ownership relations matter more than others, that ownership relations come with different moral weights.
3. Instrumental and non-instrumental
The right theory of property will note and explain the difference between objects we own (and want) for purely instrumental reasons, objects we own (and want) for instrumental reasons and for other reasons, and objects we own (and want) for purely non-instrumental reasons.
Replaceability might track this. Purely instrumental objects will be replaceable, while non-instrumental objects may or may not be replaceable.
Got any other intuitions about the right theory of property?