 The idea of progress is complex enough that it has attracted many types of criticism, and some of them seem especially hard to refute. For one thing, the determinism inherent in the idea of progress is difficult to maintain.  It is telling that many of the theorists do not incorporate their act of writing and the reception they hope for into a deterministic framework.  Second, whether we agree with the precise claims made by Diamond and Wright, it is now clear that natural limits on growth exist. The exact limits cannot be known for certain unless they are reached.  But rather than proceeding as if no environmental limits exist, it is more prudent to estimate the limits and develop policy accordingly.  It is better to slow down and come to a halt a few feet before a brick wall than to ignore it and slam into it. 