At about the same time as Brooks was describing his first results with the subsumption architecture, Chapman was completing his Master's thesis, in which he reported the theoretical difficulties with planning described above, and was coming to similar conclusions about the inadequacies of the symbolic AI model himself. Together with his co-worker Agre, he began to explore alternatives to the AI planning paradigm [Chapman and Agre, 1986].
Agre observed that most everyday activity is `routine' in the sense that it requires little - if any - new abstract reasoning. Most tasks, once learned, can be accomplished in a routine way, with little variation. Agre proposed that an efficient agent architecture could be based on the idea of `running arguments'. Crudely, the idea is that as most decisions are routine, they can be encoded into a low-level structure (such as a digital circuit), which only needs periodic updating, perhaps to handle new kinds of problems. His approach was illustrated with the celebrated PENGI system [Agre and Chapman, 1987]. PENGI is a simulated computer game, with the central character controlled using a scheme such as that outlined above.