This concluding chapter summarizes the main insights gained in this book. Emotion theories show substantial agreement in their working definition of emotions in terms of the typical and apparent properties of emotions (intensional format) and the prototypical emotions (divisio format) they want to see explained. Their constitutive explanations range from narrow to broad. The most pronounced differences reside in the causal-mechanistic explanations they propose. Five fault lines stand out centering on the questions whether (a) emotions are caused by a stimulus-driven or goal-directed process, (b) the origin of feelings is central or peripheral, (c) emotions are caused by special-purpose or general-purpose mechanisms, (d) emotions do or do not form a scientific set, and (e) the variety in the set of emotions is best captured with discrete emotions or dimensions. The chapter also examines whether there is any hope for a unifying theory integrating several theories or a general framework for conducting emotion research. Starting from a unifying theory that combines a maximum of mechanisms, a pruning stage is required based on empirical research. A speculation about the result of this pruning exercise, inspired by the goal-directed theory advocated in this book, is presented, ultimately leading to the demystification of emotion.

This chapter discussed the general precursors of the families of emotion theories to be discussed in the ensuing chapters: Darwin (1872) and James (1890b). Darwin (1872) proposed an evolutionary and eventually also a mechanistic explanation for emotional behavior, particular facial expressions. Initially goal-directed processes grow into habits (learned emotion-response links) and instincts (innate emotion-response links). Today these instincts are no longer of use, which is why they appear in weakened form as facial expressions. James (1890b), seeking a causal-mechanistic explanation for emotions themselves, proposed that stimuli activate instincts (innate stimulus-response links) and habits (learned stimulus-response links), which when enacted produce somatosensory feedback, felt as emotions. James’s (1872) theory accounted for the properties of ontogenetic and phylogenetic continuity, phenomenality, bodily aspect, heat, control precedence, and irrationality, but has difficulty delivering the right kind of (world-directed) Intentionality, and even the right kind of heat. James (1872) rejects partitioning the set of emotions into discrete subsets. Empirical evidence pro and contra James’s (1872) theory is discussed.

This chapter discusses response evaluation theories (RETs), which foreground a process of response evaluation. It zooms in on the goal-directed theory of Moors (2017a), which proposes a goal-directed cycle as the causal-mechanistic explanation of the phenomena called emotions. The cycle starts with the detection of a discrepancy between a stimulus and a first goal, which activates a second goal to reduce the discrepancy. This reduction can take the form of assimilation (of the stimulus to the goal via overt action), accommodation (of the goal to the stimulus by changing the first goal), and/or immunization (reinterpretion of the stimulus as less discrepant). Assimilation requires further selection of the action with the highest expected utility. This in turn activates a third goal to engage in the action, leading to overt somatic and motor responses and feelings. The goal-directed theory can account for continuity, a rich form of Intentionality, phenomenality, bodily aspects, heat, control precedence, and irrationality. This wide scope is combined with parsimony in that presumed emotions and non-emotional phenomena are explained by the same mechanism. The goal-directed theory does not deliver discrete emotions, but can nevertheless make sense of them. Empirical research that tests the goal-directed theory is discussed.