‘Passion’—whether Of The Christ, “toward egalitarian liberalism”, or a discontinued Snapple flavor—still enjoys wide currency in contemporary discourse. It’s generally a positive currency, too: passion invigorates life and invitiates action; the passionless person is assumed either shiftless or mechanical. In such a view, passion is some sort of ambiguous but nonetheless discrete sub-rational quality. We choose whether to endorse or deny our passions, but not whether to experience them in the first place. So ‘passion’ takes on a marginal role between physiology and freedom; we ‘have’ these passions, one supposes, by no act of free will, but they simultaneously shape our will according to their autonomous whims.

Is ‘passion’ past its expiration date, though? At one point in history, another belief in sub-rational qualities enjoyed similar currency: the concept of the ‘humors’ or ‘temperaments’. Popularized by Hippocrates, this part-biological, part-proto-psychological theory also saw sub-rational propellants for human behavior. It proposed that these latent quantities controlled human urges and desires, and that they were unresponsive to the will.

Modern medicine, of course, eventually enveloped the ‘humors’ into far more complex biochemical understanding in which physical functions of the body favor different behavioral and action patterns. Now, modern psychology, it seems, has come to render ‘passion’ as antiquated as ‘humor’. What we used to call ‘passions’ now have better names and better explanations. Yet the emotional pull of ‘passion’ remains strong. If we truly believe in the expansion of knowledge, though, we have to privilege science over sentimentality, and ‘passion’ in such a view is destined for the same fate as ‘humor’.