Earlier quoted context omitted.
Think of it this way. If you suddenly lost the ability to speak and didn't have fingers or arms and all you could do was swim, bump around, and bite things, you'd probably act a lot like a fish, but you'd still love and feel emotions like a human, we'd just have no way of knowing. We are extremely arrogant (and oddly so, in my opinion) in our assumption that "lesser" species don't have consciousness or that they have…
wait... Descartes disemboweled live dogs?!?!
https://blog.timesunion.com/animalrights/descartes-and-anima...
Gary Francione (Introduction to Animal Rights): “Descartes and his followers performed experiments in which they nailed animals by their paws onto boards and cut them open to reveal their beating hearts. They burned, scalded, and mutilated animals in every conceivable manner. When the animals reacted as though they were suffering pain, Descartes dismissed the reaction as no different from the sound of a machine that was functioning improperly. A crying dog, Descartes maintained, is no different from a whining gear that needs oil.”