When Animals Dream

David M. Peña-Guzmán / Princeton University Press / 272 pages

When Animals Dream: The Hidden World of Animal Consciousness, by philosopher Dr. David M. Peña-Guzmán, is part storytelling and part dense academic text. The book tackles a fascinating topic: Is there evidence that nonhuman animals dream, and if so, what does that tell us about their capacity for consciousness?

Beginning with vivid descriptions of studies on sleep in a variety of species, Peña-Guzmán builds a compelling case that animals do dream. In the introduction and first chapter we learn about snoozing octopuses changing color in nonrandom sequences that correspond to changes during real-life events (for example, noticing, pursuing, and consuming prey), zebra finches replaying their songs while asleep, and American Sign Language–proficient chimpanzees signing in their sleep. While these studies’ authors rarely concluded they had observed dreaming, Peña-Guzmán—whose professional interests include the history and philosophy of science—challenges readers to consider how researchers’ interpretations of their study findings often reflect their own philosophical convictions rather than scientific truths. 

In the next two chapters, Peña-Guzmán argues that evidence of dreaming is necessarily evidence of consciousness. These chapters delve deep into philosophical and neuroscientific theories of consciousness, with topics such as subjective and affective consciousness, the dream ego, lucidity, metacognition, imagination, and nightmares (the latter makes for a very difficult read, as it describes trauma experienced by animals who were deliberately tortured by experimenters or had witnessed violence at the hands of poachers and wildlife traffickers).

The last chapter closes the loop by explaining that being conscious confers moral standing; therefore, evidence of dreaming is evidence that animals are “conscious beings who matter and for whom things matter.” Contrary to the publisher’s summary, however, Peña-Guzmán does not discuss the “profound implications” this conclusion has for “contemporary debates about animal cognition, animal ethics, and animal rights.” He also fails to acknowledge that most studies reviewed in the book rely on invasive experiments on animals with electrodes implanted in their brains—a glaring omission in a book on animals as “conscious beings who matter.” Nevertheless, it is a thought-provoking book for anyone interested in animal minds and philosophy.

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