portal: Mind and Brain Consciousness has been defined loosely as a constellation of attributes of mind such as subjectivity, self-awareness, sentience, and the ability to perceive a relationship between oneself and one's environment. It has been defined from a more biological and causal perspective as the act of autonomously modulating attentional and computational effort, usually with the goal of obtaining, retaining, or maximizing specific parameters (food, a safe environment, family, mates). Consciousness may involve thoughts, sensations, perceptions, moods, emotions, dreams, and an awareness of self, although not necessarily any particular one or combination of these. Consciousness is a point of view, an I, or what Thomas Nagel called the existence of "something that it is like" to be something. Julian Jaynes has emphasized that "consciousness is not the same as cognition and should be sharply distinguished from it. ... The most common error ... is to confuse consciousness with perception." He says, "Mind-space I regard as the primary feature of consciousness". The exact definition of consciousness is still open to debate among academics.

The issue of what consciousness is, and to what extent and in what sense it exists, is the subject of much research in philosophy of mind, psychology, neuroscience, cognitive science, and artificial intelligence. Issues of practical concern include how the presence of consciousness can be assessed in severely ill individuals; to what extent non-humans are conscious and self-conscious; at what point in fetal development consciousness begins; and whether computers can achieve conscious or self-conscious states. Stuart Shieber (ed): The Turing test : verbal behavior as the hallmark of intelligence, Cambridge, Mass, MIT Press, 2004, ISBN 978-0-262-69293-9 Steven Marcus: Neuroethics: mapping the field. Dana Press, New York 2002. ISBN 978-0-9723830-0-4.

In common parlance, consciousness denotes being awake and responsive to the environment, in contrast to being asleep or in a coma.

Etymology

The word "consciousness" is derived from Latin conscientia which primarily means moral conscience. In the literal sense, "conscientia" (or "con scientia") means knowledge-with, that is, shared knowledge. The word first appears in Latin juridic texts by writers such as Cicero. Here, conscientia is the knowledge that a witness has of the deed of someone else. In Christian theology, conscience stands for the moral conscience in which our actions and intentions are registered and which is only fully known to God. Medieval writers such as Thomas Aquinas describe the conscientia as the act by which we apply practical and moral knowledge to our own actions. René Descartes has been said to be the first philosopher to use "conscientia" in a way that does not seem to fit this traditional meaning, and, as a consequence, the translators of his writings in other languages like French and English coined new words in order to denote merely psychological consciousness. These are, for instance, conscience, and Bewusstsein. However, it has also been argued that John Locke was in fact the first one to use the modern meaning of consciousness in his Essay Concerning Human Understanding, although it remains closely intertwined with moral conscience (I may be held morally responsible only for the act of which I am conscious of having achieved; and my personal identity - my self - goes as far as my consciousness extends itself). However, it is the case that Ralph Cudworth was in fact the first one to use the modern meaning of consciousness in his "True Intellectual System of the Universe" (1678). It too remains closely intertwined with moral agency, but does not in itself signify conscience. The modern sense of consciousness was therefore first found not in Descartes' work - who sometimes used the word in a modern sense, but did not distinguish it as much as Locke would do - nor in Locke's text, but Cudworth's. The contemporary sense of the word consciousness (consciousness associated with the idea of personal identity, which is assured by the repeated consciousness of oneself) was introduced by Cudworth. The word "conscience" was coined by Pierre Costes, French translator of Locke, but in the English language the modern sense first appeared in Cudworth's works. It is true, however, that Locke much influenced the subsequent reception of consciousness: in Samuel Johnson's celebrated Dictionary, Johnson gives a definition of "conscious" as "endowed with the power of knowing one's own thoughts and actions," and takes Locke's own definition of "consciousness" as "the perception of what passes in a man's own mind."