Knowledge that, knowledge how, and knowledge by acquaintance

In epistemology in general, the kind of knowledge usually discussed is propositional knowledge, also known as "knowledge that." This is distinguished from "knowledge how" and "acquaintance-knowledge". For example: in mathematics, it is known that 2 + 2 = 4, but there is also knowing how to add two numbers and knowing a person (e.g., oneself), place (e.g., one's hometown), thing (e.g., cars), or activity (e.g., addition). Some philosophers think there is an important distinction between "knowing that," "knowing how," and "acquaintance-knowledge," with epistemology being primarily concerned with the first of these.

In his paper On Denoting and his later book Problems of Philosophy Bertrand Russell stressed the distinction between "knowledge by description" and "knowledge by acquaintance". Gilbert Ryle is also credited with stressing the distinction between knowing how and knowing that in The Concept of Mind. In Personal Knowledge, Michael Polanyi argues for the epistemological relevance of knowledge how and knowledge that; using the example of the act of balance involved in riding a bicycle, he suggests that the theoretical knowledge of the physics involved in maintaining a state of balance cannot substitute for the practical knowledge of how to ride, and that it is important to understand how both are established and grounded. This position is essentially Ryle's, who argued that a failure to acknowledge the distinction between knowledge that and knowledge how leads to infinite regress.

In recent times, some epistemologists (Sosa, Greco, Kvanvig, Zagzebski) and Duncan Pritchard have argued that epistemology should evaluate people's "properties" (i.e., intellectual virtues) and not just the properties of propositions or of propositional mental attitudes

Consciousness is the quality or state of awareness, or, of being aware of an external object or something within oneself. It has been defined as: sentience, awareness, subjectivity, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind. Despite the difficulty in definition, many philosophers believe that there is a broadly shared underlying intuition about what consciousness is. As Max Velmans and Susan Schneider wrote in The Blackwell Companion to Consciousness: "Anything that we are aware of at a given moment forms part of our consciousness, making conscious experience at once the most familiar and most mysterious aspect of our lives."

Philosophers since the time of Descartes and Locke have struggled to comprehend the nature of consciousness and pin down its essential properties. Issues of concern in the philosophy of consciousness include whether the concept is fundamentally coherent; whether consciousness can ever be explained mechanistically; whether non-human consciousness exists and if so how it can be recognized; how consciousness relates to language; whether consciousness can be understood in a way that does not require a dualistic distinction between mental and physical states or properties; and whether it may ever be possible for computing machines like computers or robots to be conscious, a topic studied in the field of artificial intelligence.

At one time consciousness was viewed with skepticism by many scientists, but in recent years it has become a significant topic of research in psychology, neuropsychology, dance, and neuroscience. The primary focus is on understanding what it means biologically and psychologically for information to be present in consciousness—that is, on determining the neural and psychological correlates of consciousness. The majority of experimental studies assess consciousness by asking human subjects for a verbal report of their experiences (e.g., "tell me if you notice anything when I do this"). Issues of interest include phenomena such as subliminal perception, blindsight, denial of impairment, and altered states of consciousness produced by drugs and alcohol, or spiritual or meditative techniques.

In medicine, consciousness is assessed by observing a patient's arousal and responsiveness, and can be seen as a continuum of states ranging from full alertness and comprehension, through disorientation, delirium, loss of meaningful communication, and finally loss of movement in response to painful stimuli. Issues of practical concern include how the presence of consciousness can be assessed in severely ill, comatose, or anesthetized people, and how to treat conditions in which consciousness is impaired or disrupted.

The origin of the modern concept of consciousness is often attributed to John Locke's Essay Concerning Human Understanding, published in 1690. Locke defined consciousness as "the perception of what passes in a man's own mind". His essay influenced the 18th-century view of consciousness, and his definition appeared in Samuel Johnson's celebrated Dictionary (1755).

The earliest English language uses of "conscious" and "consciousness" date back, however, to the 1500s. The English word "conscious" originally derived from the Latin conscius (con- "together" and scio "to know"), but the Latin word did not have the same meaning as our word—it meant "knowing with", in other words "having joint or common knowledge with another".

There were, however, many occurrences in Latin writings of the phrase conscius sibi, which translates literally as "knowing with oneself", or in other words "sharing knowledge with oneself about something". This phrase had the figurative meaning of "knowing that one knows", as the modern English word "conscious" does. In its earliest uses in the 1500s, the English word "conscious" retained the meaning of the Latin conscius. For example, Thomas Hobbes in Leviathan wrote: "Where two, or more men, know of one and the same fact, they are said to be Conscious of it one to another." The Latin phrase conscius sibi, whose meaning was more closely related to the current concept of consciousness, was rendered in English as "conscious to oneself" or "conscious unto oneself". For example, Archbishop Ussher wrote in 1613 of "being so conscious unto myself of my great weakness". Locke's definition from 1690 illustrates that a gradual shift in meaning had taken place.

A related word was conscientia, which primarily means moral conscience. In the literal sense, "conscientia" means knowledge-with, that is, shared knowledge. The word first appears in Latin juridical texts by writers such as Cicero. Here, conscientia is the knowledge that a witness has of the deed of someone else. René Descartes (1596–1650) is generally taken to be the first philosopher to use conscientia in a way that does not fit this traditional meaning. Descartes used conscientia the way modern speakers would use "conscience". In Search after Truth (Inquisitio Veritatis; publ. 1701) he says "conscience or internal testimony" (conscientiâ, vel interno testimonio).

The word cognition comes from the Latin verb cognosco (con 'with' + gnōscō 'know'), itself a cognate of the Ancient Greek verb gi(g)nόsko "γι(γ)νώσκω" meaning 'I know, perceive' (noun: gnόsis "γνώσις" = knowledge), so broadly, 'to conceptualize' or 'to recognize'.

In science, cognition is the set of all mental abilities and processes related to knowledge: attention, memory & working memory, judgement & evaluation, reasoning & "computation", problem solving & decision making, comprehension & production of language, etc. Cognition is by humans conscious and unconscious, concrete or abstract, as well as intuitive (like knowledge of a language) and conceptual (like a model of a language). Cognitive processes use existing knowledge and generate new knowledge.

These processes are analyzed from different perspectives within different contexts, notably in the fields of linguistics, anesthesia, neuroscience, psychiatry, psychology, philosophy, anthropology, biology, systemics, and computer science.^{[1][page needed]} These and other different approaches to the analysis of cognition are synthesised in the developing field of cognitive science, a progressively autonomous academic discipline. Within psychology and philosophy, the concept of cognition is closely related to abstract concepts such as mind and intelligence. It encompasses the mental functions, mental processes (thoughts), and states of intelligent entities (humans, collaborative groups, human organizations, highly autonomous machines, and artificial intelligences).

Thus, the term's usage varies across disciplines; for example, in psychology and cognitive science, "cognition" usually refers to an information processing view of an individual's psychological functions. It is also used in a branch of social psychology called social cognition to explain attitudes, attribution, and group dynamics. In cognitive psychology and cognitive engineering, cognition is typically assumed to be information processing in a participant’s or operator’s mind or brain.

Cognition can in some specific and abstract sense also be artificial.