In 1962, Thomas Kuhn published a groundbreaking book entitled The Structure of Scientific Revolutions. In it, he argued that the progress of science is not gradual but (much as we now think of biological evolution), a kind of punctuated equilibrium, with moments of epochal change. When Copernicus explained the movements of the planets by postulating that they moved around the sun rather than the earth, or when Darwin introduced his ideas about the origin of species, they were doing more than just building on past discoveries, or explaining new experimental data. A truly profound scientific breakthrough, Kuhn notes, "is seldom or never just an increment to what is already known. Its assimilation requires the reconstruction of prior theory and the re-evaluation of prior fact, an intrinsically revolutionary process that is seldom completed by a single man and never overnight." Kuhn referred to these revolutionary processes in science as "paradigm shifts", a term that has now entered the language to describe any profound change in our frame of reference. Paradigm shifts occur from time to time in business as well as in science. And as with scientific revolutions, they are often hard fought, and the ideas underlying them not widely accepted until long after they were first introduced. What's more, they often have implications that go far beyond the insights of their creators. My premise is that free and open source developers are in much the same position today that IBM was in 1981 when it changed the rules of the computer industry, but failed to understand the consequences of the change, allowing others to reap the benefits. Most existing proprietary software vendors are no better off, playing by the old rules while the new rules are reshaping the industry around them. I have a simple test that I use in my talks to see if my audience of computer industry professionals is thinking with the old paradigm or the new. "How many of you use Linux?" I ask. Depending on the venue, 20-80% of the audience might raise its hands. "How many of you use Google?" Every hand in the room goes up. And the light begins to dawn. Every one of them uses Google's massive complex of 100,000 Linux servers, but they were blinded to the answer by a mindset in which "the software you use" is defined as the software running on the computer in front of you. Most of the "killer apps" of the Internet, applications used by hundreds of millions of people, run on Linux or FreeBSD. But the operating system, as formerly defined, is to these applications only a component of a larger system. Their true platform is the Internet. It is in studying these next-generation applications that we can begin to understand the true long-term significance of the open source paradigm shift." Tim O'Reilly invitation to better analyze and evaluate the processes and consequences behind our technology choices is a healthy one, and his outstanding essay provides lots of valuable insight and references to understand what kind of paradigm shift we are really in. A must-read.