It seems entirely likely that the list of A.I.’s capabilities will only grow—and so it’s tempting to wonder what, exactly, people are good for. In the past, theologians and philosophers compared us with animals and identified the ways in which we surpassed them. Now the tables aren’t so much turned as upended. In some cases, we seem to be looking upward at the machines (no human being can write with an A.I.’s fluidity and speed, for example). In others, we scratch our heads at their stupidity (no person would advise you to make a daily habit of eating “at least one small rock,” as Google’s A.I. did not long ago, when asked “How many rocks should I eat each day?”). In still other cases, we’re simply confused by the divergences between artificial and organic reasoning. An A.I. can’t fall in love, but it can express the idea of love; it can’t be an artist, but it can (maybe) create a kind of art; it can’t agonize over a consequential decision, but it can still decide. We know that there are crucial differences between a thinking computer and a person, but defining those distinctions isn’t easy.