How then does one judge a planning theory and decide what action to take? If you say the world is round, and I say it is flat, there are ways of settling our dispute. Likewise, if we differ on the dimensions of a brick pier to support a concrete beam, both can be built and we can discover whose design theory withstands the load. Planning theories are more problematical. Cities take generations to build and have many clients who judge their surroundings in different ways at different points in history, at different stages of their lives, and in different ways when engaged in different activities (work, leisure, shopping etc.).
Any one approach to planning is doomed to failure. Single-topic theories cannot deal with multi-everything cities. This failure is illustrated by the history of British housing layout from 1840 to 1990 (Turner, 1987a). The story forms a sequence of "problems' followed by "panaceas'. Each panacea was based on a planning theory. Each became a "problem' in its turn (Figure 3). Warren Housing, reviled by Engles, was succeeded by Byelaw Housing. Unwin and his friends attacked Byelaw Housing, arguing the case for Housing on Garden City Lines. Reformers, from Clough Williams Ellis to Ian Nairn, slammed the sprawling uniformity of suburbia and sub-topia. Corbusian planners argued for the superficially attractive solution of stacking the dwellings and allowing the "landscape' to flow underneath. Mixed Development was the next solution, to be followed by Design Guide Housing. Each theory had value but each caused a new problem, because it was overemphasized.
A shocking feature of the progression is the fervour with which each group of reformers, seeking new powers and new uniformities, decried the work of its predecessors. When we look back, each of the panaceas has real merit and continues to suit certain social groups. Warren housing, where it survives in old villages, is treasured. Garden suburbs have always been loved by residents. Stefan Muthesius, Oscar Newman, and many young couples, have sung the praises of the English terraced house. Others love the cell-like isolation and superb views from tower blocks. The most serious criticism of the theories that generated these schemes is that each has been too dominant, and has ruled exclusively in those dreaded ghettos: the housing estate and residential tract. Despite Jane Jacobs, estates continue to be single-purpose places. If any one theory had reigned for the 150-year period, our towns would be immeasurably poorer. Town planning is not like building brick piers.
'Housing on Garden City lines' was the panacea of the 1930s