The key phrase here is “employing their own property”. You continue to evade the central issue: the fact that a design is a creation that belongs only to the creator, it is his property and copying it is an unauthorized use. When they employ someone else’s design without permission, they are not employing their own property.
Just because an author–inventor “creates” something, it does not follow that he is entitled to own it. If I “create” a cure for scurvy by being the first to feed victims of the disease citrus fruits, am I entitled to a royalty from everyone who has a morning glass of orange juice? (And if you think that this is a silly example, consider this actual U.S. patent: “Method of Exercising a Cat,” U.S. Pat. No. 5,443,036, Aug. 22, 1995 (shining a laser light onto the floor to fascinate a cat and cause it to chase the light).
The thought-creator-as-owner argument begs the question by assuming that an idea is ownable in the first place. Yet ideas cannot be ownable for the simple reason that they exist in the minds of men and one cannot in any practical sense have control over the content of another’s mind.
Example: if someone writes a poem and copyrights it, under the creator-owner theory he presumably owns all forms of it. Suppose you memorize the poem. If, as you say, the creation “belongs only to the creator,” then the poet would own not only his copy but also the memory of the poem in your mind – and could, if we follow the logic of intellectual property, sue you because “copying it is an unauthorized use.” But simply reading a poem and committing it to memory is hardly the same thing as breaking into a home and stealing the silverware. Therefore, it is fallacious to treat thoughts the same as tangible goods. As Arnold Plant explained, “It is a peculiarity of property rights in patents (and copyrights) that they do not arise out of the scarcity of the objects which become appropriated. They are not a consequence of scarcity. They are the deliberate creation of statute law, and, whereas in general the institution of private property makes for the preservation of scarce goods, tending . . . to lead us ‘to make the most of them,’ property rights in patents and copyrights make possible the creation of a scarcity of the products appropriated which could not otherwise be maintained.”
Furthermore, if, as you say, “design is a creation that belongs only to the creator,” why would patents and copyrights be for limited periods of time? We do not say the owner-builder of a skyscraper should have a limited lease on his creation. The fact that intellectual property is treated as a special case in law certainly suggests that it rests on a shakier philosophical foundation than titles to tangible property.
Ownership is the exclusive right to use and disposal. The fact that a design “goes into someone’s head and becomes part of their memory” does not give them the right to use and dispose of that design. Perception is not creation and does not attentuate the creator’s ownership.
But you have already stated that with regard to a creation, “copying it is an unauthorized use.” So if we adhere to the theory that “a creation that belongs only to the creator” then the creator of a poem (or an equation or a solution or an invention) would own every instance of that creation, including not only those that those existed on paper or in three dimensions but also as thoughts. In order to defend the idea that the creator owner has authority over all instances of his creation, one has also to accept the notion that he has authority over the minds of others.
Looking at someone else’s design is not the equivalent of conceiving and creating it in the first place. The mere fact that a design can be copied does not argue that it is okay to copy it. Property rights are not a function of the ease or difficulty of violating them.
To a certain extent they are. Theoretically, we could award property titles for the pleasure our actions give to others, so that I would be entitled to collect royalties from anyone who passes within earshot of my window when I play the guitar. After all, I “created” pleasure; am I not entitled to the fruits of my labor? Of course, the difficulty of collecting such royalties would render my rights moot. Intellectual property has very similar practical difficulties. As Stephan Kinsella says, “The distinction between creation and discovery is not clearcut or rigorous. Nor is it clear why such a distinction, even if clear, is ethically relevant in defining property rights. . . Patent law has no moorings to objective borders of actual, tangible property, and thus is inherently vague, amorphous, ambiguous, and subjective. For the latter reason alone, one would think that Objectivists – ardent, self-proclaimed defenders of objectivity and opponents of sub-jectivism – would oppose patent and copyright.”
No, this does not mean that the creator “absurdly owns part of the other persons head.” The creator only owns the exclusive right to use and dispose of his design. Others may think about it, talk about it, imagine it, contemplate it, make up poems about it – but only the creator can use and dispose of it.
But if you have memorized someone’s copyrighted poem without his permission, you most certainly have violated the poet’s “exclusive right to use and dispose” of his creation. Thus arguments for intellectual property ultimately result in the absurdity of owning other’s thoughts. After all, if some property can be regarded as “intellectual,” mustn’t it reside in the intellect?