Apparent order can emerge in systems without intentional directions. Economists often argue that planned actions disrupt the behavior of a free-market system that would naturally arrive at a predictable, stable, and desirable equilibrium if just left alone. There is a famous quote from Bernard Siegan, which says "the least fallible of city planners is the free market." A recent article by Samuel Staley also suggests that Houston's non-zoning, market-driven land use approach helped housing weather the subprime mortgage storm.
You could also find heated discussion of land use regulations vs. libertarianism at the Cyburbia Forums - the oldest and most active English language urban planning message board on the Internet. See links below for more information on the debate.
So the questions are: If you are asked about the conflicts between urban planning and the free-market system, will you defend the planning profession? If yes, how? And if no, why?
FYI: Response must be posted at least six hours prior to the next class (i.e., by Tuesday noon)