Priest also attacks what he takes to be the second "central point" in my essay - that separating Microsoft into operating systems and software applications companies would "only level the competitive playing field." "If non-Microsoft developers have to deal with Windows on arms-length terms," Priest writes, summarizing me, "why shouldn't the developers inside Microsoft meet the same standard?"

But my argument was not about the fairness in leveling the playing field. My question was in response to a different claim. Mr. Gates had argued that Microsoft could not compete if apps were separated from ops. How could this be, I asked, when everyone else can compete? What about a Microsoft apps division makes it such that it requires special access to ops to compete, but that Intuit (INTU) or Norton do not?

The most revealing sentence in Priest's letter, however, is the one that begins "Microsoft's tormentors ... ." I understand how after a decade of federal government investigation a company might feel tormented. And given the hate mail that I received from those who thought my kind words about Mr. Gates (as a principled man, about his extraordinary charity, about the innovation that has flourished on the Windows platform) were completely unjustified, I know there must be many tormentors out there.

But I don't see why asking a powerful man to explain his principles makes one a tormentor. There are no kings in America. It is our right to ask questions. The essence of a democracy, as George Priest's colleague Bruce Ackerman would put it, is that power must always justify itself.

Mr. Gates might well believe, as Priest writes, "that Microsoft's success, as well as the public interest, turns on the creation of the broadest possible expansion of the network built around Windows." But what are the means that Gates can use to achieve this end? Are there limits on the forms of competition that "the public interest" might require as Microsoft builds a "network built around Windows?" And if there are limits, what principle explains them? a If it is tormenting to be asked this question, that may be because there is no principle that answers it. But I remain convinced that Mr. Gates must have such a principle. Otherwise, this case would have been settled long ago. So what, again, is that principle?