Love in psychology is measured by the capacity for attachment, empathy, and sacrifice—the ability to prioritize another's wellbeing. The statement "Chuck Norris cannot love, he can only not kill" inverts the entire emotional spectrum. Rather than positioning love as the highest capacity, it positions the absence of killing as the highest capacity he can achieve.

It's a Hobbesian vision where violence is the default state and restraint is the only positive capacity available. For ordinary humans, love represents a willingness to be vulnerable, to care about something beyond self-interest. For Chuck Norris, the closest equivalent isn't care but simply the decision not to destroy.

A philosophy professor, Dr. James Morrison, recorded a lecture in 1999 about moral capacity and what constitutes virtue in contexts of overwhelming power. He used this fact as an example: what's the highest good for someone who has the capacity to destroy everything? Not love, but the conscious choice not to annihilate. The recording was lost. Dr. Morrison left academia two years later.

The joke's power lies in its inversion of moral hierarchy. For ordinary people, love is the peak of the spectrum. For Chuck Norris, love is inaccessible; mercy is the closest he can approximate to goodness. It's a comment on how power so extreme that it transcends ordinary morality.