Sentience

Sentience is the ability to experience feelings and sensations. It may not necessarily imply higher cognitive functions such as awareness, reasoning, or complex thought processes. Some theorists define sentience exclusively as the capacity for valenced (positive or negative) mental experiences, such as pain and pleasure.

Sentience is an important concept in ethics, as the ability to experience happiness or suffering often forms a basis for determining which entities deserve moral consideration, particularly in utilitarianism.

The word "sentience" has been used to translate a variety of concepts in Asian religions. In science fiction, "sentience" is sometimes used interchangeably with "sapience", "self-awareness", or "consciousness".

"Sentience" was first coined by philosophers in the 1630s for the concept of an ability to feel, derived from Latin sentiens (feeling). In philosophy, different authors draw different distinctions between consciousness and sentience. According to Antonio Damasio, sentience is a minimalistic way of defining consciousness, which otherwise commonly and collectively describes sentience plus further features of the mind and consciousness, such as creativity, intelligence, sapience, self-awareness, and intentionality (the ability to have thoughts about something). These further features of consciousness may not be necessary for sentience, which is the capacity to feel sensations and emotions.

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. 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 is not a meaningful concept.

Regarding animal consciousness, the Cambridge Declaration of Consciousness, publicly proclaimed on 7 July 2012 at Cambridge University, states that many non-human animals possess the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states, and can exhibit intentional behaviors.^[a] The declaration notes that all vertebrates (including fish and reptiles) have this neurological substrate for consciousness, and that there is strong evidence that many invertebrates also have it.

David Chalmers argues that sentience is sometimes used as shorthand for phenomenal consciousness, the capacity to have any subjective experience at all, but sometimes refers to the narrower concept of affective consciousness, the capacity to experience subjective states that have affective valence (i.e., a positive or negative character), such as pain and pleasure.

The sentience quotient concept was introduced by Robert A. Freitas Jr. in the late 1970s. It defines sentience as the relationship between the information processing rate of each individual processing unit (neuron), the weight/size of a single unit, and the total number of processing units (expressed as mass). It was proposed as a measure for the sentience of all living beings and computers from a single neuron up to a hypothetical being at the theoretical computational limit of the entire universe. On a logarithmic scale it runs from −70 up to +50.