At first sight, jealousy seems to be a very unreasonable feeling. Especially the actions in consequence of jealousy are in several situations hard to comprehend for an external observer. This raises the question, if the emotion jealousy, which leads people to unreasonable activities, can be called unreasonable itself as well. How about the relationship between rationality and the emotion jealousy without considering the following actions? Many philosophers called emotions in general irrational some claimed the relationship between reason and emotion to be interdependent. Is the emotion influencing the reason or is the reason affecting emotions? Or are emotions rather an aid to rationality? Is a feeling like jealousy due to its dependency on temper a proof for the irrationality of emotions? For Descartes, reason and emotion are two distinct entities, while for Hume an emotion is neither called rational nor irrational. Aristotle by contrast calls for the rationality of emotions. After an illustration of the relationship between reason and emotion defended by the philosophers, who do not claim the emotion to be rational, I elaborate the role of emotion as an aid to rationality. Therefore, I will introduce a concept of the emotion as an aid to bounded rationality. I will then go on pointing out the rational and irrational elements of the emotion jealousy in order to conclude with an argument, that is defending a more differentiated and relative view on the rationality of emotions.
Emotions could be defined as the contrary of rationality. According to this point of view, the emotions are affective states, while the reason is characterised by cognitive states. For Descartes reason is often in opposition to emotion, as he claims in “The Passions of the Soul”. Comparable to his dualistic position of the mind and the body, he takes emotions for sensations acting separately from the cognitive states of the mind. The two parts seem to influence each other, in the way that the reason is able to impede the control of the soul on its passions. In order that elements are able to influence each other, they need to be distinct, so it seems to be clear, that for him, an emotion can’t have the characteristic of reason at the same time. Is it possible, that reason is completely isolated from emotions and the other way round, can we imagine that such a complex thing like an emotion is completely liberated from any rationality? After Descartes’ position, the emotions or in other terms passions act upon us, not the other way round. As passions happen on us, in this way, reason could be understood as a second step in an action after the first step of the passion happening on us. Let’s take the example of fear. In an affective state of fear, where one is on the point of running away, the reason in connection with will as a counterpart of the emotion, is able to stop the person. So could it be the case, that the emotion plays the role of provoking the rational reaction?
This question leads me to the position of David Hume that he takes up in his “From a Treatise of Human Nature”. For Hume emotions are neither rational nor irrational. He calls the reason the “slave of passions”. Hence, reason has the function of satisfying our emotions. Thereafter emotion and reason aren’t separated in the way that Descartes argued. If reason should satisfy our emotions, they aren’t able to be opposed one to each other. Rather are the emotions setting goals, which should be achieved with the aid of knowledge, elaborated by the reason. In my understanding, the reason is treated as means. According to Cohon, Hume defends the position, that “reason alone cannot move us to action; the impulse to act itself must come from passion”. So what does this point of view mean for a specific emotion like jealousy? For emotions like grief or joy, it is quite intelligible, how Hume’s argumentation works. Taking grief as an example. Given Person A and B feel connected, they are very close and share experiences as well as thoughts, good and bad moments with each other, in other words, they like or even love each other. B is suddenly dying, A loses a good friend, a formerly enriching connection, and it is an emotional loss that leaves in some ways emptiness. We call the current emotion of a “grief”. After Hume’s assumptions, this emotion directly arises from the pain – in my example caused by the loss of a loved person. Now, we can imagine a few reactions of Person A. Perhaps she is crying, possibly going to the funeral, speaking with other people about the sad happening, writing in a diary about the painful experience. These actions aren’t encouraged by the reason of person A, but by the emotion. It is imaginable, that Person A could have reacted in other ways, like jumping off a bridge instead of going on. The choice of the action under several possibilities to react is influenced by the reason of Person A, but the impulse to act comes from the grief. As I said before, for Hume the emotion grief arises directly from the pain, but what about more complex emotions such as jealousy, love or hatred? After Cohon, Hume proceeds on the assumption that these kinds of feelings don’t arise directly from pain but rather produce pain. Let’s go back to the example of jealousy. A man observes his wife chatting, laughing and enjoying a moment with another man that he doesn’t know. Even if he is sure, by virtue of reasonable reflections, that the relationship between his wife and the other man doesn’t have any influence on the relationship between him and his wife and the shared moment of the two strangers is not sexually motivated in any sense, for the husband this could be an unpleasant situation. The unpleasant feeling of jealousy doesn’t arise from the pain the spouse is feeling. In this case it appears to be the other way round. The jealous man feels perhaps offended in his self-esteem or maybe his conception of a relationship contains a strict exclusivity, which doesn’t fit to the image his wife is giving him by showing interest in another man. So, it is the jealousy that is causing a painful experience, which manifests itself in rage or even disappointment. The approach of Hume concerning the relationship between reason and emotion showed us in this case, that jealousy as an emotion can cause pain – another emotion. But is the emotion rational? What role does the reason play for the jealous husband? And what about the former question whether the emotion could play a role as an elicitation of the reason?
 Descartes, René: From the Passions of the Soul, 20-30.
 Hume, David : From A Treatise of Human Nature, 44-54.
 Aristotle : On the Soul, 1-3.; Aristotle : Nicomachean Ethics, 72-75.
 Descartes, René: From the Passions of the Soul, 20-30.
 ibid., 26.
 Descartes, René : From the Passions of the Soul, 26.
 Hume, David: From A Treatise of Human Nature, 44-54.
 cited in: Cohon 2010: Hume's Moral Philosophy, Chapter 3.
 cf. ibid., Chapter 3.
 Cohon 2010: Hume's Moral Philosophy, Chapter 2.
 Cohon 2010 : Hume's Moral Philosophy, Chapt. 2.