Goodwill and ill will are about intention: the will is for good or ill. These intentions are expressed through action and inaction, word and deed, and-especially-thoughts. How do you feel when you sense another person taking potshots at you in her mind? What does it feel like to take potshots of your own? Ill will plays a lot of mini-movies in the simulator, those little grumbling stories about other people. Remember: while the movie is running, your neurons are wiring together.

Ill will tries to justify itself. In the moment, the rationalizations sound plausible, like the whisperings of Wormtongue in The Lord of the Rings. Only later do we realize how …