We have seen thus far that standard accounts of the ways in which planning is theorized in relation to processes of urban and regional development are flawed in numerous ways. These flaws can be summarized under the follow­ ing headings: rationalism; essentialism; idealism; functionalism and abstractionism. To clarify the meaning of each of these in order, then it will be recalled that the first problematical characteristic, that designated rationalism, arises from the assumption that the logic of processes operating in the real world can be equated with the logic of concepts employed to represent those processes. It was shown how adopting a rationalist view of planning imposed impossibly rigid criteria for what should constitute real world planning action, the effects of which were to mystify the planning process and to reduce it to a hopelessly relativistic construct of the theorists’ mental processes. As a result an adequate theorization could not be forth­ coming since there is no way of knowing which of any number of theorists’ personal constructs is preferable and why. The rationalist theory of planning cannot begin to address the indeterminate ways in which planning policies emerge and are implemented since it is only coterminous with those aspects of planning which conform to the model of pure rationality. Since this is, by definition, unachievable planning rationalism must be relegated to the position of a normative but meaningless ideal.