Sentience

While it has been traditionally assumed that sentience and sapience are, in principle, independent of each other, there are criticisms of that assumption. One such criticism is about recognition paradoxes, one example of which is that an entity that cannot distinguish a spider from a non-spider cannot be arachnophobic. More generally, it is argued that since it is not possible to attach an emotional response to stimuli that cannot be recognized, emotions cannot exist independently of cognition that can recognize. The claim that precise recognition exists as specific attention to some details in a modular mind is criticized both with regard to data loss as a small system of disambiguating synapses in a module physically cannot make as precise distinctions as a bigger synaptic system encompassing the whole brain, and for energy loss as having one system for motivation that needs some built-in cognition to recognize anything anyway and another cognitive system for making strategies would cost more energy than integrating it all in one system that use the same synapses. Data losses inherent in all information transfer from more precise systems to less precise systems are also argued to make it impossible for any imprecise system to use a more precise system as an "emissary", as a less precise system would not be able to tell whether the outdata from the more precise system was in the interest of the less precise system or not.[7][8]

The original studies by Ivan Pavlov that showed that conditioned reflexes in human children are more discriminating than those in dogs, human children salivating only at ticking frequencies very close to those at which food was served while dogs drool at a wider range of frequencies, have been followed up in recent years with comparative studies on more species. It is shown that both brain size and brain-wide connectivity contribute to make perception more discriminating, as predicted by the theory of a brain-wide perception system but not by the theory of separate systems for emotion and cognition.[9]

According to Thomas Nagel in his paper What Is It Like to Be a Bat?, consciousness can refer to the ability of any entity to have subjective perceptual experiences, or as some philosophers refer to them, "qualia"—in other words, the ability to have states that it feels like something to be in.[10] Some philosophers, notably Colin McGinn, believe that the physical process causing consciousness to happen will never be understood, a position known as "new mysterianism." They do not deny that most other aspects of consciousness are subject to scientific investigation but they argue that qualia will never be explained. Other philosophers, such as Daniel Dennett, argue that qualia are not a meaningful concept.[11]

Regarding animal consciousness, according to the Cambridge Declaration of Consciousness, which was publicly proclaimed on 7 July 2012 at the Cambridge University, consciousness is that which requires specialized neural structures, chiefly neuroanatomical, neurochemical, and neurophysiological substrates, which manifests in more complex organisms as the central nervous system, to exhibit consciousness.^[a] Accordingly, only organisms that possess these substrates, all within the animal kingdom, are said to be conscious. Sentience is not mentioned anywhere in this document.[12] Sponges, placozoans, and mesozoans, with simple body plans and no nervous system, are the only members of the animal kingdom that possess no consciousness.

The 18th-century philosopher Jeremy Bentham compiled enlightenment beliefs in Introduction to the Principles of Morals and Legislation, and he included his own reasoning in a comparison between slavery and sadism toward animals:

The French have already discovered that the blackness of the skin is no reason why a human being should be abandoned without redress to the caprice of a tormentor [see Louis XIV's Code Noir]... What else is it that should trace the insuperable line? Is it the faculty of reason, or, perhaps, the faculty of discourse? But a full-grown horse or dog is beyond comparison a more rational, as well as a more conversable animal, than an infant of a day, or a week, or even a month, old. But suppose the case were otherwise, what would it avail? the [sic] question is not, Can they reason? nor, Can they talk? but, Can they suffer?[25]

In the 20th century, Princeton University professor Peter Singer argued that Bentham's conclusion is often dismissed by an appeal to a distinction that condemns human suffering but allows non-human suffering, typically "appeals" that are logical fallacies (unless the distinction is factual, in which case the appeal is just one logical fallacy, petitio principii). Because many of the suggested distinguishing features of humanity—high intelligence; highly complex language; etc.—are not present in marginal cases such as mute humans, young children, deaf humans, and mentally disabled humans, it appears that the only distinction is a prejudice based on species alone, which animal-rights supporters call speciesism—that is, differentiating humans from other animals purely on the grounds that they are human. His opponents accuse him of the same petitio principii.