Ideas and theories of have changed over time, from the early ideas presented by the ancient Greeks to modern 20th- and 21st-century philosophy. These ideas and theories have been profoundly influenced over the years by philoso­phy, , naturalism, and more recently by psychoanalytic psychology, neuroscience, and quantum mechanics. Presently there is no uni­formly accepted definition of consciousness; rather it has become more of an integrated theory con­sisting of several schools of thought. As science and technology evolve and humankind begins to develop a better understanding of the primate brain and how it works and the apparently subjec­tive reality surrounding it, more is beginning to be understood about consciousness.

Ancient Greeks

The ancient Greeks provided early speculations on the human . Plato was one of the first think­ers to attempt to formulate the definition of what would become known as consciousness. Of course at that time there was no word equivalent that had the wide range in meaning that the word con­sciousness has in 20th- and 21st-century thought. Therefore the ancient Greeks speculated on what was known as mind.

Plato was one of the first to develop the idea of the mind. He proposed that the mind is something in the head and that objects existed as impressions in the material world. However, he maintained that these impressions were visible forms that are conveyed through what he called “the mind’s eye” by a third nature: light. Plato further elaborated that these visible forms were observed by the mind’s eye as mental content arranged as geo­metrical forms. Plato proposed that these geo­metrical forms were provided by the .

Another ancient Greek philosopher who expanded on the early ideas of consciousness was Aristotle, who was a physicalist, meaning that he believed that all things, including human beings, are intrinsically incorporated in a material uni­verse. This is why he thought that the study of the soul (or psyche and to an extent consciousness) would fall within the confines of the science of nature. Aristotle made note of the concept of sig­nals (sight and sound), the transmission of infor­mation (those signals reaching the human mind), and in many ways the notion of perception (the mind’s realization of those signals).

Aristotle’s idea of the mind, in general, sup­ported Plato’s idea that mind was something in the head (the brain), and that an object in the material world existed as an extension of time. However, Aristotle proposed that an impression of these objects was received by the sense organs (eyes and ears), and that the impressions received were relayed in a changed state to the mind and were extended throughout time and space.

Early Theories of Consciousness

Rene Descartes (1596-1650) was another influential thinker on the topic of consciousness. He was also responsible for coining the very famous Latin phrase cogito ergo sum, which in English means, “I think, therefore I am.” While Plato and Aristotle maintained that faculties of the mind and soul could not be out­lined or represented by mere terms of physiology, Descartes expanded their ideas into what is know as dualism (or Cartesian dualism). Descartes proposed that the physical world occurs in an extended form in the brain (which is material), but through a particular process it is then condensed into a nonextended form in the mind where thought occurs (which is nonmate­rial). He also believed (much like Plato) that thoughts were produced by the soul, which is also nonmaterial. Therefore, according to Descartes’ theory of dualism, the actual process of consciousness involves a material and a nonmaterial component.

In theory, Descartes’ philosophical idea of con­sciousness was similar to that of Plato’s idea of mind. In addition, the concept of consciousness being partly a product of an immaterial soul was maintained and undoubtedly a by-product of popu­lar Christian thinking at that time. Also due to the indoctrinating influence of Christianity, which upheld that only our species has a soul, Cartesian dualism would imply that consciousness is exclusive to humans. The idea that only humans possess con­sciousness is also known as the anthropistic theory.

The Neurological and Evolutionary Perspectives of Consciousness

The neurological theory or Darwinian theory insists that consciousness is a direct result of the centralization of the nervous system, which was brought forth by progressive evolution. This theory implies that only humans and higher mammals with this anatomic tendency can possess conscious­ness. In addition, because the centralization of the nervous system has evolved over time, conscious­ness itself would implicitly have had to evolve over time. This would mean that the type of conscious­ness that Homo sapiens sapiens experiences now would have to be different to some degree com­pared to the consciousness that was experienced by our early hominid ancestors.

The idea that our current form of conscious­ness is not immutable, that it has changed over time and may be subject to change in the future, would seem to refute the dogmatic notion that consciousness is exclusive to our species, and that in fact animals (this is known as the “animal the­ory”) or at the least higher mammals (such as chimpanzees) may experience different forms of consciousness similar to our own.

It is worth noticing that toward the end of the 19th century the influence of naturalism, due primar­ily to the writings of Charles Darwin, was influencing philosophical opinions about consciousness and causing them to change. The theme of consciousness was beginning to be viewed as a natural and biologi­cal process rather than a spiritual phenomenon. This would later motivate neuroscientists to explore and propose neurological bases of consciousness.

Psychoanalytical Ideas of Consciousness

Sigmund Freud (1856-1939), the founder of psychoanalysis, was influenced by Charles Darwin’s concept that our species is part of the animal kingdom (not separate from it as previously believed) and his mentor Ernst Brucke’s concept of “dynamic physiology,” which applied the laws of thermodynamics (in particular the law of conservation) to living systems, in particular humans. These concepts compelled Freud to form his psychoanalytical theory, which he applied to the understanding of human consciousness.

Freud proposed that in human consciousness there is a conflict in place between pleasure-seeking behavior (known as the pleasure principle) and the rules or laws of the environment and society (known as the reality principle). He illustrated that this conflict is internalized by three properties. First is the Id, which operates in co-ordinance with the pleasure principle (known as the primary process). Second is the Ego, which attempts to enforce the reality principle (known as the secondary process); Freud considers the ego to be a human’s consciousness. Third is the Superego, which according to Freud represents society and cultural restraints.

Freud’s psychoanalytic contribution to the study of consciousness is that it allowed investi­gators to investigate further the consciousness of humans scientifically and opened up the doors to explore it psychologically. Freud’s approach was novel because it superseded the conflict of the material versus nonmaterial basis of conscious­ness. His approach also focused on the individual experience and how it is internalized, interpreted, and expressed psychologically by the mind.

Freud also paved the way for consciousness to be viewed later in terms of introspectionism and individual psychotherapy. Introspectionism is a school of thought that maintains that conscious­ness is best understood in first-person accounts. Therefore it upholds that the conscious experience can be explained only in terms of data acquired from introspection. Individual psychotherapy is a school of thought that maintains that conscious­ness is a result of an organism’s (or person’s) adaptive capacity. Psychotherapy typically involves scheduled discussions between a patient and a mental health professional.

The psychoanalytical approach to explaining con­sciousness was different from previous philosophical approaches to consciousness in that it did not merely propose ideas, but rather attempted to make definitions based on psychological observations. It is important to note that during the early 20th century, consciousness was beginning to develop several different subdefini­tions and new schools of thought. These opinions involved solely an individual’s account of the conscious experience in order to define what consciousness was.

Twentieth-Century Philosophies of Consciousness

During the 20th century, metaphysics began to play a more critical role in engaging the problems of understanding consciousness. Implicitly, meta­physical thinkers were beginning to question the underlying theoretical principles of the already established theories of consciousness.

An important figure in the early 20th century was Alfred North Whitehead, who was a mathematician and a philosopher. He pointed out that there were limitations to our understanding of consciousness because the descriptions of our conscious experience were based in 19th-century ideas of space and time. According to Whitehead, 19th-century materialist views of time and space were not grounded in observa­tion and scientific reality. He also believed that mind and nature are part of the same process, and in order to understand them scientifically one must understand relations within nature and the simultaneity of events.

Another important 20th-century thinker was Gilbert Ryle, a professor of metaphysical philoso­phy. He was most notable for his deliberately abu­sive declaration that the “official doctrine,” which hails from Descartes, is absurd. The Cartesian doc­trine was that human bodies are in space and are therefore subject to the mechanical laws that gov­ern all bodies in space, yet human minds are not in space and are therefore not subject to those same mechanical laws. Ryle proposes that the human body is a complex unit and therefore the human mind is another complex unit; however, the mind is a complex unit composed of a different form (or forms) of material than the human body.

During Ryle’s time psychological schools of thought known as “cognitism” were addressing the issue of consciousness. Cognitivists maintained that in understanding the mind, one must under­stand the “internal” rule-bound manipulation of symbols. Ryle opposed this school of thought vehemently with his famous “Ryle’s Regress,” which is essentially an argument discrediting the cognitivist theories of consciousness, claiming that they do not explain what they propose to explain.

More recently Daniel C. Dennett, a former stu­dent of Gilbert Ryle, has become well known for his of consciousness, which is the theory that consciousness is based upon the premise that the brain acts as an information processor. According to Dennett, there exist a variety of sen­sory inputs from a given event; therefore there are a variety of possible interpretations of these inputs that arrive in the brain. Once these sensory inputs arrive in the brain they are interpreted at different times, which gives rise to a succession of discrimina­tions. These discriminations then become available for eliciting behavior to that event.

It can be clearly seen that views of conscious­ness have changed over time, especially in the 20th century. Theories of consciousness have obviously become more complex, as seen in Dennett’s mul­tiple drafts model compared with the generaliza­tions constituting the ancient Greeks’ idea of the mind. This is mostly due to advances in under­standing biology and humankind’s place in nature (naturalism); the maturation of metaphysics; and the ensuing rigorous reevaluation of previous philosophical thought. Another common theme in 20th-century philosophy regarding consciousness is the rejection of previous dogmas, as illustrated by thinkers such as Whitehead and Ryle.

Twenty-First Century Explanations of Consciousness

As has been illustrated, the ancient ideas and early philosophies of consciousness have not only changed over time, but in some cases, as shown, were discredited and replaced in the 20th century. New thoughts in the 21st century may do the same to the views established in the 20th century.

Sir Roger Penrose originally proposed (actually in the late 20th century) the theory of the , which asserts that consciousness is a quan­tum mechanical phenomenon. Quantum mechan­ics are scientific laws that are not seen on the macroscopic level; rather they become apparent at the atomic and subatomic levels. According to theory, classical physics is inade­quate to fully explain consciousness; the quantum model, which is associated with a number of intractable paradoxes, must be invoked. A major difficulty surrounding theory is that many of its hypotheses require investigation for which no adequate technology capable of pro­viding scientific proof yet exists. For now it remains only a theoretical explanation.

The Future of Consciousness

Eventually theories and models of consciousness will reach a limit in their attempt to explain con­sciousness. In the future, a more comprehensive study of neurophysiology, neurochemistry, and quantum mechanics (to rule in or rule out its valid­ity) should begin to stabilize scientific thinking on what consciousness actually is as a process, and how it is able to occur in the brain or elsewhere. In addition, advances in technology may give rise to penetrating insights that in turn could give credi­bility to the idea that human consciousness per­haps is composed of different type(s) of matter, which is why we currently are having difficulty understanding it entirely.

As we continue to struggle to understand our own consciousness, an intriguing concept has emerged: that perhaps different forms of conscious­ness may exist among animals, cells, molecules (in particular DNA), and even atoms. These different forms of consciousness would be unobservable to humans, who do not completely understand their own consciousness. There is also the possibility that with the advent of artificial intelligence, forms of artificial consciousness or silicon-based con­sciousness may be created. No less intriguing is the question of what types of exobiological (alien) life forms may exist elsewhere in the universe and what types of conscious experience they may possess.

John K. Grandy

See also Amnesia; Aristotle; Bergson, Henri; ; Creativity; Critical Reflection and Time; Darwin, Charles; Dejâ Vu; Descartes, Rene; Memory; Plato; Whitehead, Alfred North

Further Readings

Dennett, D. (1991). Consciousness explained (The

Phillips Collection). Boston: Little, Brown.

Edelmann, G. M., & Tononi, G. (2001). A universe of consciousness: How matter becomes imagination. New York: Basic Books.

Grandy, J. (2005). Consciousness. In H. J. Birx (Ed.), Encyclopedia of anthropology (Vol. 2, pp. 563-566). Thousand Oaks, CA: Sage.

Grandy, J. (2005). Freud, Sigmund. In H. J. Birx (Ed.), Encyclopedia of anthropology (Vol. 3, pp. 1005­1007). Thousand Oaks, CA: Sage.

Penrose, R., & Gardner, M. (1989). The emperor’s new mind: Concerning computers, minds, and the laws of physics. Oxford, UK: Oxford University Press.

Pinker, S. (1999). How the mind works. New York: Penguin.

What do you think?



Nicolaus Copernicus

Nicolaus Copernicus