I am not talking about unconscious emotions. If we have emotions that never ripple the surface of consciousness, they are beyond the scope of this discussion. I am talking about times when we are aware of emotional feelings, whether or not we can give these feelings a name.
Even for conscious emotional states, I think it is impossible to specify a set of minimal cognitive prerequisites. In some ways it is analogous to the attempt to specify the defining features of mental illness. Some people are delusional but not unhappy, some experience debilitating panic attacks even though they "know" there is nothing to be afraid of, some are racked with physical pain that has no identifiable physical cause. The history of attempts to define insanity in a way that bears some relation to reality is testimony to the futility of seeking necessary and sufficient causes.
Publication Information & Recommended Citation
Ellsworth, Phoebe C. "Levels of Thought and Levels of Emotion." In The Nature of Emotion: Fundamental Questions, edited by P. Ekman and R. J. Davidson, 192-6. Series in Affective Science. Oxford: Oxford Univ. Press, 1994.