You know the difference between being in a good mood when you tend to be happy and cheerful, and being in a bad mood when you tend to be sad and grumpy. Moods are different from emotions in three main respects. First, moods tend to be much more long-lasting, going for hours or days, whereas an emotion may only last minutes. Second, emotions are about something specific, such as a person or situation, but moods are much more diffuse with no identifiable object. A mood is a general feeling, not a reaction to a particular situation. Third, moods are not as intense as emotions, which can be strong feelings such as exhilaration, terror, or despair. In contrast, you might not be consciously aware that you are in a good or bad mood until you reflect on your response to situations.
Moods and emotions are linked. When you are in a bad mood, you are inclined to have negative emotions such as being sad, angry, or afraid about something. But when you are in a good mood, you are inclined to have positive emotions such as being happy or hopeful about something. So the nature of emotions should inform us about the nature of moods.
According to the semantic pointer theory of emotions, emotions are patterns of firing in large groups of neurons that integrate neural representations of situations, cognitive appraisals of those situations, and physiological changes (Thagard and Schröder, 2014, Thagard 2018). For example, being happy that you are on vacation is a brain process that binds together your neural representations of (1) the vacation, including both words and images, (2) your appraisal that the vacation is accomplishing your goals such as having fun, and (3) changes in your body such as increased heart rate and lower cortisol.
But what are moods that operate without representations of particular situations? I propose that moods are dispositions to have emotions. Salt has a disposition to dissolve in water, and glass bottles have a disposition to break when dropped. But what is a disposition?
Philosophers often treat dispositions as counterfactual conditional (Choi & Fara, 2012). For example, to say that a teaspoon of salt has a disposition to dissolve in water is to say that if it had been placed in water then it would have dissolved. Unfortunately, the standard philosophical way of dealing with such counterfactuals is in terms of possible worlds. To say that the salt would have dissolved is to say that there is some possible world similar to ours in which it does dissolve.
This characterization of dispositions in terms of counterfactuals and possible worlds is useless both psychologically and physically. It shows no understanding of the physics of salt, and taps into obscure metaphysics about possible worlds rather than into the psychology of how people think about dispositions.
A better way of understanding counterfactuals comes from the artificial intelligence researcher Judah Pearl (2000). He says that you can evaluate a counterfactual by considering a causal model that shows how different factors interact with each other. For example, the mechanism of solubility of table salt is well understood because we know that sodium chloride results from binding positive sodium atoms with negative chlorine atoms. When salt is placed in water, the ions separate. Knowledge of these mechanisms justifies the conclusion that salt is soluble even if it doesn’t actually get placed in water. We have reason to believe that a counterfactual is true when we know underlying mechanisms that predict the results of various manipulations.
Similarly, the disposition of moods to produce positive or negative emotions is the result of the underlying mechanisms that produce emotions. Being in a mood is having processes going on in your body, and in your brain’s unconscious appraisals of situations, that together produce particular kinds of emotions in response to particular kinds of situations. For example, if you are in a good mood, then your physiology and background thinking are operating in ways that incline you to interpret new situations positively. More specifically, if you have some of the physiological hallmarks of good emotions such as stable heart rates, breathing rates, and cortisol levels, and if you have been making mostly positive appraisals about things, then these background processes represented in your brain will make you more likely to respond to new situations with positive emotions.
So moods can be understood in terms of the same brain mechanisms as emotions.
Choi, S., & Fara, M. (2012). Dispositions. Stanford Encyclopedia of Philosophy. Retrieved from https://plato.stanford.edu/entries/dispositions/
Pearl, J. (2000). Causality: Models, reasoning, and inference. Cambridge: Cambridge University Press.
Thagard, P. (2018). Brain-mind: From neurons to consciousness and creativity. Oxford: Oxford University Press. Fall publication.
Thagard, P., & Schröder, T. (2014). Emotions as semantic pointers: Constructive neural mechanisms. In L. F. Barrett & J. A. Russell (Eds.), The psychological construction of emotions (pp. 144-167). New York: Guilford.