Byte.com: The Business of Open Source

It conflicts with the common sense of most professional
artists and engineers to give away freely the source that underlies
their work. The foundation of any business that depends on
intellectual property is that people who develop copyrightable or
patent-able material carefully protect their creations either
legally or by maintaining trade secrets. Money is typically made in
these businesses through planned obsolescence.
Growth is
achieved through the re-licensing of products as new versions
render the old obsolete. Open source proponents prefer licenses
that provide freedom from obsolescence and eliminate dependency on
the original owner of intellectual property.”

“The value of open source licensing is the guarantee of freedom
that it provides. No open source product need ever become obsolete
because the product’s source serves as the foundation upon which
future derived works are created, and everyone is free to use the
source to derive new works. If you play by the rules of true open
source, you never have to pay license fees for rights to
intellectual property. So, how can open source, a model of doing
business that flies in the face of age-old business logic, coexist
with traditional, closed, models of intellectual property

“Open source is not public domain. When you release your source
code to the public under the terms of an open source license you do
not relinquish your copyright or patent rights. Open source
licenses grant conditional rights to members of the general public
willing to comply with the terms of the open source license. You
can still sell private licenses to individuals and companies that
are unwilling or unable to comply with the terms of the open source
license. This is one of the freedoms afforded to you, the developer
and copyright or patent holder, that is never mentioned in any of
the documents discussing open source philosophy. Your freedoms as a
property owner are not supposed to be forfeited simply because you
believe in the open source philosophy.”