An important puzzle in the study of complex systems is the conditions under which the aggregation of information from interacting agents results in a stable or an unstable collective outcome. We present a general framework for thinking about the stability and instability of collective outcomes...

This paper describes a computer program, called Copycat, that models how people make analogies. It might seem odd to include such a topic in a collection of papers mostly on the immune system. However, the immune system is one of many systems in nature in which a very large collection of...

Rationality is a complex behavioral theory that can be parsed into statements about preferences, perceptions, and process. This paper looks at the evidence on rationality that is provided by behavioral experiments, and argues that most cognitive anomalies operate through errors in perception...

The spatial model of voting is a benchmark in theories purporting to explain political behavior. Yet, evidence against the accuracy of both the assumptions and predictions of the spatial model is accumulating in the scholarly literature. One long-held result of spatial theory is that incumbents...