The man-made distinction between being alive and living one's life allows us to group animals, along with plants, into a homogenous mass—nature's great "oneness." The glory and tragedy of individual existence is thus left only to the human race. Are humans the only creatures, however, to live their own lives? In this book, philosopher Florence Burgat ponders under what conditions a life—human or animal—might be qualified as consciously lived.

Burgat first considers the distinction between "simply being alive" and conscious existence—the feature that commonly distinguishes animals from humans. The author criticizes the philosophies that deny the animal a conscious existence. Approaching the possibility of animals' conscious existence by differentiating the animal's organism from that of a machine, she explores the notion of animals' subjectivity, their thought, and their resistance to inhumane treatment. In the last part of the book the author invites the reader to move past sympathy. We should, according to Burgat, observe animals based on a phenomenology of their existence, and as "subjects of a life".

As she develops her own theory, Florence Burgat looks back critically at the philosophies that have focused on animals, and proposes a new reflection based on her certainty that animals belong to the class of beings that live a conscious existence.