Against Intellectual Monopoly

and economics tradition. This is the myth that ideas in the public domain are like common pastures.
Because of this, it is argued, the public domain suffers from congestion and
overuse, and intellectual property rights are necessary to provide appropriate incentives to "maintain" existing works.

    One reason for rights in ordinary property is indeed to prevent congestion
and overuse. For example, if a pasture is public, I do not take account of
the negative effect my grazing sheep have on the availability of grass for
your sheep. Because roads are public, I do not consider that my driving on
the road makes it more difficult for you to get to work. Because the ocean
is public, I do not consider that catching fish leaves fewer for you. This is
known as the tragedy of the commons, and in each case it means that the
pasture, road, or ocean will be overused.
    Is the public domain for ideas like a common? Does my using ideas
in the public domain have an adverse effect on your ability to use them?
Certainly common sense suggests that "there can be no overgrazing of
intellectual property ... because intellectual property is not destroyed or
even diminished by consumption. Once a work is created, its intellectual
content is infinitely multipliable."39 That I might make use of an idea does
not make you less able to use it. Indeed, it seems obvious that welfare is
increased when more people become cognizant of a useful idea, whereas
overall productive capacity is not increased when more sheep try to eat from
the same square foot of pasture.
    Congress and the Supreme Court apparently do not agree, and recently
William Landes and Richard Posner, rejecting exactly the statement by
Karjala we just quoted, have claimed that "recognition of an `overgrazing'
problem in copyrightable works has lagged. ,40 In fact it has not, because
there is no coherent theory or evidence pointing to such a problem.
    The overgrazing argument holds that just as by grazing my cows on your
grass I reduce the grass available for your cows, so by selling copies of an
idea, I reduce the profitability to you of selling the same idea. Notice first
that the analogy with the cow and the grass has already been broken by its
own proponents: they do not argue, as the analogy requires, that by selling
my copies of an idea I reduce the availability of that same idea, or any
other idea for that matter, to you. They claim, instead, that I am reducing
your profitability in selling other copies of the same idea, and thereby is
the fallacy. To see the fallacy, consider applying the reduced profitability
argument to the case of food. If my restaurant sells Ricardo a large meal, he
is not likely to go across the street to your restaurant and buy another; my
selling him a large meal does not prevent you from using your food, but
it does prevent you from selling it to Ricardo. So, too, with ideas. If I sell Ricardo a copy of my Bible, I do not prevent you from making copies of
your Bible, but I will reduce your profit because Ricardo will not buy from
you. By way of contrast, by taking fish from the sea, I am not merely taking
your customers but also taking an economically useful good or service.

    Economists refer to the former as a pecuniary externality and the latter
as a technological externality. Pecuniary externalities are a good thing - the
incentive to steal customers is an essential part of the normal and efficient
functioning of the competitive system. Technological externalities are a
bad thing, leading to overuse. Hence, ideas in the public domain are like
fish in the common pond only if, because they are in the public domain
and because of people making copies of them, they generate technological
externalities. Do they?
    There are precious few examples of what the externalities might be that
involve ideas. Landes and Posner express concern about Mickey Mouse: "If
because copyright had expired anyone were free to incorporate the Mickey
Mouse character in a book, movie, song, etc., the value of the character
might plummet."41 The value for whom? It cannot be the social value of the
Mickey Mouse character that plummets - this increases when more people
have access. Rather, it is the market price of copies of the Mickey Mouse
character that plummets: normally, this is the socially good effect of an
increase in output. Next they assert that "the public [would] rapidly tire of
Mickey Mouse."42 But this is in fact the