The theory proposes that each of the three broad classes of emotions – Event-based emotions, Agent-based emotions, and Object-based emotions – is evaluated in terms of different criteria, that is, different kinds of knowledge representations: events are evaluated in terms of their desirability relative to goals, agents’ actions are evaluated in terms of their praiseworthiness relative to standards and norms, and objects in terms of their appeal relative to tastes. Desirability, praiseworthiness, and appeal are proposed as the primary source of intensity for the corresponding classes of emotions, while representations of goals, standards, and tastes together comprise the underlying value system. Considered in its entirety, the value system is cast as a relatively complex virtual organization of goals and their interdependencies together with a less complex arrangement of standards and tastes. It is considered to be a dynamic and virtual structure, with much of it being computed as needed. A detailed worked example is used to illustrate how, in general terms, the evaluations of events and the actions of agents might be computed.

This chapter discusses a number of passages from Galen’s work that illustrate his idea of dialectic as a tool for scientific reasoning and discovery in particular. Through logical methods such as division the researcher identifies observable properties of the thing under examination (e.g. the heart, or brain) that indicate its hidden cause or essence, i.e. function (e.g. being the centre of a particular psychic faculty) in the context of theory formation. The medical practitioner for his part will profit from dialectical method when it comes to establishing a diagnosis. The notion of indication or sign is pivotal in that its bridges the stage of discovery and that of confirmation through demonstrative proof. In addition, ‘dialectical’ serves as a label for plausible assumptions and arguments in cases where truth is unattainable or at any rate has not yet been established through demonstrative proof. Various influences are involved in Galen’s version of dialectic: Plato’s Phaedrus and Timaeus, Academic epistemology, Aristotle’s works on scientific method as well as input from the medical schools, most notably Rationalist ideas (e.g. indication). His resulting position can best be described as an original synthesis developed with a view to the interests of the medical theorist and practitioner.