In an episode of the television show Girls, a friend says to the main character, Hannah, that the heart wants what the heart wants. Hannah replies, “You do know who you're quoting, right?”
I wondered too, and a Web search turned up three sources: a popular song by Selena Gomez, a justification by Woody Allen for his involvement with Mia Farrow’s adopted daughter, and a letter by the poet Emily Dickinson, which presumably is the actual origin.
What does it mean to say that the heart wants what it wants? And is it true?
The heart is often used as a figure of speech (metonymy) for emotions, as in Pascal’s remark that the heart has its reasons that reason does not know. So I think that the meaning of the saying, "The heart wants what it wants,” is that emotions such as love are not under conscious, cognitive control. For example, you cannot simply decide to fall in love with somebody, no matter how suitable. Similarly, you cannot just decide to stop loving somebody, no matter how hopeless.
On the other hand, you can decide to do things that increase the likelihood that you will fall in love with someone, such as having deep, intimate conversations and gazing into each other’s eyes. And you might decide to try to fall out of love with someone by avoiding the person, focusing on negative features, and becoming attracted to someone else. These occurrences are hard to explain using the two most common theories of emotions.
The cognitive appraisal theory of emotions says that emotions are judgments about how well a situation fits with your goals, so that happiness is an estimate of goal satisfaction and sadness is an estimate of goal dissatisfaction. On this theory, it should be fairly easy to control your emotions, because you can reappraise the situation and figure out whether falling in love accomplishes your relationship goals. But emotions are never that simple.
The alternative theory of emotions is that they are just reactions to physiological changes, such as heart rate, breathing, and hormone levels. The physiological perception view of emotions fits well with the idea that the heart wants just what the heart wants, putting feelings outside of cognitive control. But mere physiology doesn’t explain how the brain differentiates among emotions that are physiologically similar, such as fear/anger and shame/guilt, nor how the brain produces socially complex emotions such as pride, gratitude, envy, and embarrassment.
The problem is resolved by viewing emotions as a parallel brain process that simultaneously performs and integrates cognitive appraisal and physiological perception. This integration can be performed by neural representations called semantic pointers that are capable of binding representations of the situation, bodily signals, and the results of evaluation of the situation with respect to goals.
This integration explains why emotions are partly, but only partly, controllable by cognition. Reappraisal performed by yourself or with the help of a friend or therapist may be limited in the extent it can modify physiological states. Physiological modification might be helped by other, more physical interventions, such as exercise, meditation, and medication.
On this interpretation, it is only partly true that the heart wants what the heart wants, because there is some limited capacity for cognitive reappraisal that contributes to emotional change. But this capacity can sometimes bring it about that the heart wants what the brain wants.