Philosophy of mind is the branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body. The mind-body problem, or the relationship of the mind to the body, is commonly seen as the central issue in philosophy of mind, although there are other issues concerning the nature of the mind that do not involve its relation to the physical body.

Dualism and monism are the two major schools of thought that attempt to resolve the mind-body problem. Dualism is the position that mind and body are in some way separate from each other. It can be traced back to Plato, Aristotle, and the Samkhya and Yoga schools of Hindu philosophy, but it was most precisely formulated by René Descartes in the 17th century. Substance dualists argue that the mind is an independently existing substance, whereas Property dualists maintain that the mind is a group of independent properties that emerge from and cannot be reduced to the brain, but that it is not a distinct substance.

Many modern philosophers of mind adopt either a reductive or non-reductive physicalist position, maintaining in their different ways that the mind is not something separate from the body. These approaches have been particularly influential in the sciences, particularly in the fields of sociobiology, computer science, evolutionary psychology and the various neurosciences. Other philosophers, however, adopt a non-physicalist position which challenges the notion that the mind is a purely physical construct.

Reductive physicalists assert that all mental states and properties will eventually be explained by scientific accounts of physiological processes and states. Non-reductive physicalists argue that although the brain is all there is to the mind, the predicates and vocabulary used in mental descriptions and explanations are indispensable, and cannot be reduced to the language and lower-level explanations of physical science. Continued neuroscientific progress has helped to clarify some of these issues. However, they are far from having been resolved, and modern philosophers of mind continue to ask how the subjective qualities and the intentionality of mental states and properties can be explained in naturalistic terms.

The term intentionality was introduced by Jeremy Bentham as a principle of utility in his doctrine of consciousness for the purpose of distinguishing acts that are intentional and acts that are not. The term was later used by Edmund Husserl in his doctrine that consciousness is always intentional, a concept that he undertook in connection with theses set forth by Franz Brentano regarding the ontological and psychological status of objects of thought.

It has been defined as “aboutness”, and according to the Oxford English Dictionary it is “the distinguishing property of mental phenomena of being necessarily directed upon an object, whether real or imaginary”. It is in this sense and the usage of Husserl that the term is primarily used in contemporary philosophy. The concept of intentionality has its foundation in scholastic philosophy with the earliest theory being associated with St. Anselm’s ontological argument for the existence of God and his tenets distinguishing between objects that exist in understanding and objects that exist in reality.

A major problem within intentionality discourse is that participants often fail to make explicit whether or not they use the term to imply concepts such as agency or desire, or whether it involves teleology. Most philosophers use intentionality to mean something with no teleological import. Thus, a thought of a chair can be about a chair without any implication of an intention or even a belief relating to the chair. For philosophers of language, intentionality is largely an issue of how symbols can have meaning.

In current artificial intelligence and philosophy of mind, intentionality is a controversial subject and sometimes claimed to be something that a machine will never achieve. John Searle argued for this position with the Chinese room thought experiment, according to which no syntactic operations that occurred in a computer would provide it with semantic content. As he noted in the article, Searle’s view was a minority position in artificial intelligence and philosophy of mind.

Ecstasy is subjective experience of total involvement of the subject, with an object of his or her awareness. Because total involvement with an object of our interest is not our ordinary experience since we are ordinarily aware also of other objects, the ecstasy is an example of altered state of consciousness characterized by diminished awareness of other objects or total lack of the awareness of surroundings and everything around the object. For instance, if one is concentrating on a physical task, then one might cease to be aware of any intellectual thoughts. On the other hand, making a spirit journey in an ecstatic trance involves the cessation of voluntary bodily movement.

For the duration of the ecstasy the ecstatic is out of touch with ordinary life and is capable neither of communication with other people nor of undertaking normal actions. Although the experience is usually brief in physical time, there are records of such experiences lasting several days or even more. Subjective perception of time, space and/or self may strongly change or disappear during ecstasy. The word is often used in mild sense, to refer to any heightened state of consciousness or intense pleasant experience. It is also used more specifically to denote states of awareness of non-ordinary mental spaces, which may be perceived as spiritual.

Ecstasy can be deliberately induced using religious or creative activities, meditation, music, dancing, breathing exercises or physical exercise. The particular technique that an individual uses to induce ecstasy is usually also associated with that individual’s particular religious and cultural traditions. Sometimes an ecstatic experience takes place due to occasional contact with something or somebody perceived as extremely beautiful or holy, or without any known reason.

People interpret the experience afterward according to their culture and beliefs: as a revelation from God, a trip to the world of spirits or a psychotic episode. When a person is using an ecstasy technique, he usually does so within a tradition. When he reaches an experience, a traditional interpretation of it already exists. The experience together with its subsequent interpretation may strongly and permanently change the value system and the worldview of the subject.

Indefinite Monism is a philosophical conception of reality that asserts that only Awareness is real and that the wholeness of Reality can be conceptually thought of in terms of immanent and transcendent aspects. The immanent aspect is denominated simply as Awareness, while the transcendent aspect is referred to as Omnific Awareness.

Awareness in this system is not equivalent to consciousness. Rather, Awareness is the venue for consciousness, and the transcendent aspect of Reality, Omnific Awareness, is what consciousness is of.

Within this system anything whatsoever can arise from Omnific Awareness, thus the use of the term “indefinite” in labeling this monism. What does arise as the existents that we are conscious of is conditioned by the affections of Awareness for its display. Thus this system does away with the idea of an active, creative force called Free Will and replaces it with an active volitional component known as affections, that does not itself create anything, whether movement or structure, but instead, constrains the possibilities of what arises naturally.

The distinction between physical phenomena and mental phenomena is also removed by this system. Omnific Awareness gives rise to everything – thus the use of the term omnific – and this includes thoughts that phenomenally arise in brains as well as existents that arise phenomenally as things in the world. By removing this distinction this system cuts off the inevitable paradoxes that otherwise arise in philosophical systems. The implications of this move create a number of novel, but necessary, modifications in current categorizations of ideas about reality and our study of it.

For instance, ontology – the study of being – is necessitated by the assumption of a physical world of separate things, but when viewed surjectively ontology collapses into epistemology – the study of the methods or grounds of knowledge. Similarly, by removing the distinction between mental and physical phenomena the tensions created in dualist understandings of reality of how the mental and physical interact with one another are dispelled. Surprisingly, the removal of this distinction also completely removes the need for claims of metaphysical realms of being or metaphysical processes, thus collapsing all of reality into this reality.

The term intentionality was introduced by Jeremy Bentham as a principle of utility in his doctrine of consciousness for the purpose of distinguishing acts that are intentional and acts that are not. The term was later used by Edmund Husserl in his doctrine that consciousness is always intentional. It has been defined as “aboutness”, and according to the Oxford English Dictionary it is “the distinguishing property of mental phenomena of being necessarily directed upon an object, whether real or imaginary”.

The concept of intentionality was reintroduced in 19th-century contemporary philosophy by the philosopher and psychologist Franz Brentano, who described intentionality as a characteristic of sentience, a “mental phenomena”, by which it could be set apart from insentience, or natural “physical phenomena”. He used such phrases as “reference to a content,” the “direction towards an object” and “the immanent objectivity.” Brentano coined the expression “intentional inexistence” (existence in) to indicate the ontological status of mental phenomena directed upon objects that do not exist. For him, the property of being intentional, of possessing intentional objectiveness, was key to his psychological thesis distinguishing mental phenomena from physical phenomena, as physical phenomena sustains no intentionality.

A major problem within intentionality discourse is that participants often fail to make explicit whether or not they use the term to imply concepts such as agency or desire, or whether it involves teleology. Dennett explicitly invokes teleological concepts in the ‘intentional stance’. However, most philosophers use intentionality to mean something with no teleological import. Thus, a thought of a chair can be about a chair without any implication of an intention or even a belief relating to the chair. For philosophers of language, intentionality is largely an issue of how symbols can have meaning. 

In current artificial intelligence and philosophy of mind intentionality is a controversial subject and sometimes claimed to be something that a machine will never achieve. John Searle argued for this position with the Chinese room thought experiment, according to which no syntactic operations that occurred in a computer would provide it with semantic content. As he noted in the article, Searle’s view was a minority position in artificial intelligence and philosophy of mind.

A strange loop arises when, by moving up or down through a hierarchical system, one finds oneself back where one started. It is a hierarchy of levels, each of which is linked to at least one other by some type of relationship. A strange loop hierarchy, however, is “tangled” (Hofstadter refers to this a “heterarchy”), in that there is no well defined highest or lowest level; moving through the levels one eventually returns to the starting point, i.e., the original level. Examples of strange loops that Hofstadter offers include: many of the works of M. C. Escher, the information flow network between DNA and enzymes through protein synthesis and DNA replication, and self-referential Gödelian statements in formal systems.

In I Am a Strange Loop, Hofstadter defines strange loops as follows:

“ What I mean by “strange loop” is — here goes a first stab, anyway — not a physical circuit but an abstract loop in which, in the series of stages that constitute the cycling-around, there is a shift from one level of abstraction (or structure) to another, which feels like an upwards movement in a hierarchy, and yet somehow the successive “upward” shifts turn out to give rise to a closed cycle. That is, despite one’s sense of departing ever further from one’s origin, one winds up, to one’s shock, exactly where one had started out. In short, a strange loop is a paradoxical level-crossing feedback loop.

Hofstadter claims a similar “flipping around of causality” happens in minds possessing self-consciousness. The mind perceives itself as the cause of certain feelings, (“I” am the source of my desires), while scientifically, feelings and desires are strictly caused by the interactions of neurons, and ultimately, the probabilistic laws of quantum mechanics.

Thought is a mental process which allows an individual to model the world, and so to deal with it effectively according to their goals, plans, ends and desires. Words referring to similar concepts and processes include cognition, idea, and imagination. Thinking involves the cerebral manipulation of information, as when we form concepts, engage in problem solving, reasoning and making decisions. Thinking is a higher cognitive function and the analysis of thinking processes is part of cognitive psychology.

Memory is an organism’s ability to store, retain, and subsequently recall information. Although traditional studies of memory began in the realms of philosophy, the late nineteenth and early twentieth century put memory within the paradigms of cognitive psychology. In recent decades, it has become one of the principal pillars of a new branch of science called cognitive neuroscience, a marriage between cognitive psychology and neuroscience.

Imagination is accepted as the innate ability and process to invent partial or complete personal realms the mind derives from sense perceptions of the shared world. The term is technically used in psychology for the process of reviving in the mind percepts of objects formerly given in sense perception. Imagined images are seen with the “mind’s eye”. One hypothesis for the evolution of human imagination is that it allowed conscious beings to solve problems, and hence increase an individual’s fitness, by use of mental simulation.

Consciousness in mammals including humans, is an aspect of the mind generally thought to comprise qualities such as subjectivity, sentience, and the ability to perceive the relationship between oneself and one’s environment. It is a subject of much research in philosophy of mind, psychology, neuroscience, and cognitive science. Some philosophers divide consciousness into phenomenal consciousness, which is subjective experience itself, and access consciousness, which refers to the global availability of information to processing systems in the brain. Phenomenal consciousness has many different experienced qualities, often referred to as qualia.

Mind refers to the aspects of intellect and consciousness manifested as combinations of thought, perception, memory, emotion, will and imagination, including all of the brain’s conscious and unconscious cognitive processes. Mind is often used to refer especially to the thought processes of reason. Subjectively, mind manifests itself as a stream of consciousness.

There are many theories of the mind and its function. The earliest recorded works on the mind are by Zarathushtra, the Buddha, Plato, Aristotle and other ancient Greek, Indian and Islamic philosophers. Pre-scientific theories, based in theology, concentrated on the relationship between the mind and the soul, the supernatural, divine or god given essence of the person. Modern theories, based on scientific understanding of the brain, theorize that the mind is a product of the brain and has both conscious and unconscious aspects.

The question of which attributes make up the mind is also much debated. Some argue that only the “higher” intellectual functions constitute mind, particularly reason and memory. In this view the emotions love, hate, fear and joy, are more “primitive” or subjective in nature and should be seen as different from the mind. Others argue that the rational and the emotional sides of the human person cannot be separated, that they are of the same nature and origin, and that they should all be considered as part of the individual mind.

In popular usage mind is frequently synonymous with thought. It is that private conversation with ourselves that we carry on inside our heads. Thus we “make up our minds,” “change our minds” or are “of two minds” about something. One of the key attributes of the mind in this sense is that it is a private sphere to which no one but the owner has access. No one else can know our mind. They can only interpret what we consciously or unconsciously communicate.