In this post, I tackle the perennial “problem of other minds,” especially as it applies to nonhuman animals. We never have direct access to the experience of others, but only to the contents of our own consciousness. We can observe their behavior, scan their brain activity, and (in the case of fellow humans) listen to their reports of experience. We generally reason by analogy from our own case, and conclude that other humans exhibiting similar, relatively intelligent behavior are conscious. But things get stickier as we shift to the nonhuman: to other animals, life forms, and inorganic entities with significantly different compositions, behaviors, and ways of communicating (if any).