Javaness2 wrote:is intellectual property different to physical property?
It is different because it is not scarce.
You can ask: what is the point of property anyway? Why is it moral for me to restrict someone from using my property? The answer is that we desire to live in a non-violent society and minimize the amount of conflict. That is the goal of the law. That is why it makes sense to assign property rights -- to figure out whose claim on a piece of property is better, so that if a conflict arises, we can clearly see who the "winner" is.
This makes sense to do for scarce objects. For non-scarce objects, however, there is no conflict of use -- if you use my idea, it in no way precludes me from using it. So, what's the justification for me to prevent you from using it? (Especially since what I am doing is preventing you from using
your physical objects, on which the idea is stored.)
The argument about sales, etc., is irrelevant, because you don't own potential future sales. Even if your sales drop as a result of my use of your idea, I did not steal anything that you owned.
The other problem is that ideas are simply properties of physical objects. They never exist without physical objects "holding them". To sell a book without selling information contained within is like to sell a rose without selling its red color, its smell, the softness of its petals.
So, if I listen to a DVD that you produced and memorized a song on the DVD, does it mean that you own a piece of my brain where this song is stored? Do I have to pretend I don't know the song?