IP exists in your head. You have knowledge that no one else has and it is your property.
IP law recognizes this ground truth and creates a legal framework that allows IP to be traded in the economy which creates an incentive for people to share their IP.
What do you mean by "in your head"? A book I have printed, a photograph I have printed, a trademark that can be printed, these are tangible artifacts and the original IP.
IP law recognizes this ground truth and creates a legal framework that allows IP to be traded in the economy which creates an incentive for people to share their IP.