Ginsberg raises two issues for our consideration: (1) universal plans that do not allow cognitive actions (run-time problem solving) might need an exponential amount of space or circuitry for their realization and (2) universal plans that do allow cognitive actions will spend so much time on these actions that the universal plan itself can be largely superfluous. In sum, depending on whether planning is allowed to supplement a universal plan, the universal plan itself is likely to be either infeasible or superfluous, respectively. Let me clear up some areas of potential confusion. Although universal plans had the title role in Ginsberg's article, he is actually discussing a small group of related endeavors that are more commonly known as reactive Universal plans address the tension between reasoned behavior and timely response by caching reactions for classes of possible situations. This technique reduces the average time required to select a response at the expense of the space required to store the cache--the classic timespace tradeoff.

Universal plans address the tension between reasoned behavior and timely response by caching reactions for classes of possible situations. This technique reduces the average time required to select a response at the expense of the space required to store the cache-the classic time-space trade-off. In his article, Matthew Ginsberg argues from the time extreme and against the space extreme. Although I find both extremes undesirable, I defend an increase in space consumption.