This morning, the driver of my taxi here in Montreal advanced his own theory of joy. “Joy,” he said, “is anything you love to do.” But this theory of his has attenuating complications. As my driver said, “When a serial killer murders people, he feels joy too.”

Can this be possible? We think of joy as a wholesome, innocent sort of feeling — how could something so horrific bring joy? It seems to violate one of the key premises of joy, that joy comes from things which are generally good or at least neutral for humanity, not things with damaging consequences. There are joys that have a mischievous feel which I call transgressions, but these transgressions are notable for having no real harmful consequences: the trivial destruction of bubble wrap, the illicit pleasure of jumping on the bed, the forbidden delight of dessert before dinner, where the only thing ruined is an appetite. (And as Jerry Seinfeld says, it doesn’t really matter if you ruin your appetite because there’s always another one right behind it.)

Joy may not always be universal, but it usually has the potential to be shared and appreciated by others through participation, observation, or retelling. I may not myself enjoy spinning until I’m dizzy, but watching a trio of girls do so probably would bring a smile to my face.

Not so with murder, which makes me say that while a serial killer might feel pleasure from his actions, he doesn’t feel what we call joy. It may feel good for him, but it’s not transcendent, it’s not taking him out of his everyday prism and changing his perspective. If anything, like an addict, it’s only deepening his narrow field of existence. In that case, we might say the serial killer feels a sort of euphoria, an emotional high that does not shift your perspective, but just provides a temporary peak.

My thinking on this is evolving, but it is a worthwhile practical challenge to the theory. I’d love to know what people think. Do serial killers feel joy?