Abstract

There is an enduring tension in thinking about the architecture of systems that select behaviours, including evolved organisms. One line of reasoning supports convergence in control systems and conversion of the values of all options into a common currency, in part because this seems the best or only way of trading off costs and benefits associated with outcomes of varying types. A competing consideration supports parallelism or other forms of fragmentation, because of inefficiencies associated with integration, and suspicion towards general-purpose cognitive systems. In addition, recent neuroscience has given particular attention to the question of how partly independent ‘habit based’ and ‘planning based’ decision-systems might interact. The issues here are, at least in part, a special case of the more general integration versus parallelism tension. This tension provides a useful framework for thinking about the implementation of different kinds of sensitivity to risks of various types, the variety of mechanisms by means of which risk sensitivity might be modulated, and how risk might be traded off against other components of value or disincentive. I describe the tension, briefly survey some of the relevant empirical evidence, and conclude with tentative observations on the topic of risk.