Solipsism (/ˈsɒlɪpsɪzəm/ (listen); from Latin solus, meaning 'alone', and ipse, meaning 'self') is the philosophical idea that only one's own mind is sure to exist. As an epistemological position, solipsism holds that knowledge of anything outside one's own mind is unsure; the external world and other minds cannot be known and might not exist outside the mind. As a metaphysical position, solipsism goes further to the conclusion that the world and other minds do not exist. This extreme position is claimed to be irrefutable, as the solipsist believes themself to be the only true authority, all others being creations of their own mind.
There are varying degrees of solipsism that parallel the varying degrees of skepticism:
Metaphysical solipsism is a variety of solipsism. Based on a philosophy of subjective idealism, metaphysical solipsists maintain that the self is the only existing reality and that all other realities, including the external world and other persons, are representations of that self, and have no independent existence. There are several versions of metaphysical solipsism, such as Caspar Hare's egocentric presentism (or perspectival realism), in which other people are conscious, but their experiences are simply not present.
Epistemological solipsism is the variety of idealism according to which only the directly accessible mental contents of the solipsistic philosopher can be known. The existence of an external world is regarded as an unresolvable question rather than actually false. Further, one cannot also be certain as to what extent the external world exists independently of one's mind. For instance, it may be that a God-like being controls the sensations received by one's brain, making it appear as if there is an external world when most of it (excluding the God-like being and oneself) is false. However, the point remains that epistemological solipsists consider this an "unresolvable" question.
Methodological solipsism is an agnostic variant of solipsism. It exists in opposition to the strict epistemological requirements for "knowledge" (e.g. the requirement that knowledge must be certain). It still entertains the points that any induction is fallible. Methodological solipsism sometimes goes even further to say that even what we perceive as the brain is actually part of the external world, for it is only through our senses that we can see or feel the mind. Only the existence of thoughts is known for certain.
Importantly, methodological solipsists do not intend to conclude that the stronger forms of solipsism are actually true. They simply emphasize that justifications of an external world must be founded on indisputable facts about their own consciousness. The methodological solipsist believes that subjective impressions (empiricism) or innate knowledge (rationalism) are the sole possible or proper starting point for philosophical construction. Often methodological solipsism is not held as a belief system, but rather used as a thought experiment to assist skepticism (e.g. Descartes' Cartesian skepticism).
Denial of material existence, in itself, does not constitute solipsism.
A feature of the metaphysical solipsistic worldview is the denial of the existence of other minds. Since personal experiences are private and ineffable, another being's experience can be known only by analogy.
Philosophers try to build knowledge on more than an inference or analogy. The failure of Descartes' epistemological enterprise brought to popularity the idea that all certain knowledge may go no further than "I think; therefore I exist" without providing any real details about the nature of the "I" that has been proven to exist.
The theory of solipsism also merits close examination because it relates to three widely held philosophical presuppositions, each itself fundamental and wide-ranging in importance:
To expand on point 2 a little further, the conceptual problem here is that the previous assumes mind or consciousness (which are attributes) can exist independent of some entity having this capability, i.e., that an attribute of an existent can exist apart from the existent itself. If one admits to the existence of an independent entity (e.g., your brain) having that attribute, the door is open. (See the Brain in a vat.)
Some people hold that, while it cannot be proven that anything independent of one's mind exists, the point that solipsism makes is irrelevant. This is because, whether the world as we perceive it exists independently or not, we cannot escape this perception (except via death), hence it is best to act assuming that the world is independent of our minds. For example, if one committed a crime, one is likely to be punished, causing potential distress to oneself even if the world was not independent of one's mind; therefore, it is in one's best interests and is most convenient to assume the world exists independently of one's mind.
There is also the issue of plausibility to consider. If one is the only mind in existence, then one is maintaining that one's mind alone created all of which one is apparently aware. This includes the symphonies of Beethoven, the works of Shakespeare, all of mathematics and science (which one can access via one's phantom libraries), etc. Critics of solipsism find this somewhat implausible. However, since, for example, people are able to construct entire worlds inside their minds while having dreams when asleep, and people have had dreams which included things such as music of Beethoven or the works of Shakespeare or math or science in them, solipsists do have counter-arguments to justify their views being plausible.
Much of the point of the Sophists was to show that "objective" knowledge was a literal impossibility. (See also comments credited to Protagoras of Abdera).
The foundations of solipsism are in turn the foundations of the view that the individual's understanding of any and all psychological concepts (thinking, willing, perceiving, etc.) is accomplished by making an analogy with his or her own mental states; i.e., by abstraction from inner experience. And this view, or some variant of it, has been influential in philosophy since Descartes elevated the search for incontrovertible certainty to the status of the primary goal of epistemology, whilst also elevating epistemology to "first philosophy".
George Berkeley's arguments against materialism in favour of idealism provide the solipsist with a number of arguments not found in Descartes. While Descartes defends ontological dualism, thus accepting the existence of a material world (res extensa) as well as immaterial minds (res cogitans) and God, Berkeley denies the existence of matter but not minds, of which God is one.
One of the most fundamental debates in philosophy concerns the "true" nature of the world—whether it is some ethereal plane of ideas or a reality of atomic particles and energy. Materialism posits a real 'world out there,' as well as in and through us, that can be sensed—seen, heard, tasted, touched and felt, sometimes with prosthetic technologies corresponding to human sensing organs. (Materialists do not claim that human senses or even their prosthetics can, even when collected, sense the totality of the 'universe'; simply that what they collectively cannot sense cannot in any way be known to us.)
Materialists do not find this a useful way of thinking about the ontology and ontogeny of ideas, but we might say that from a materialist perspective pushed to a logical extreme communicable to an idealist (an "Away Team" perspective), ideas are ultimately reducible to a physically communicated, organically, socially and environmentally embedded 'brain state'. While reflexive existence is not considered by materialists to be experienced on the atomic level, the individual's physical and mental experiences are ultimately reducible to the unique tripartite combination of environmentally determined, genetically determined, and randomly determined interactions of firing neurons and atomic collisions.
As a correlative, the only thing that dreams and hallucinations prove are that some neurons can reorganize and 'clean house' 'on break' (often reforming according to emergent, prominent, or uncanny cultural themes), misfire, and malfunction. But for materialists, ideas have no primary reality as essences separate from our physical existence. From a materialist "Home Team" perspective, ideas are also social (rather than purely biological), and formed and transmitted and modified through the interactions between social organisms and their social and physical environments. This materialist perspective informs scientific methodology, insofar as that methodology assumes that humans have no access to omniscience and that therefore human knowledge is an ongoing, collective enterprise that is best produced via scientific and logical conventions adjusted specifically for material human capacities and limitations.
Modern Idealists, on the other hand, believe that the mind and its thoughts are the only true things that exist. This is the reverse of what is sometimes called classical idealism or, somewhat confusingly, Platonic idealism due to the influence of Plato's Theory of Forms (εἶδος eidos or ἰδέα idea) which were not products of our thinking. The material world is ephemeral, but a perfect triangle or "beauty" is eternal. Religious thinking tends to be some form of idealism, as God usually becomes the highest ideal (such as Neoplatonism). On this scale, solipsism can be classed as idealism. Thoughts and concepts are all that exist, and furthermore, only the solipsist's own thoughts and consciousness exist. The so-called "reality" is nothing more than an idea that the solipsist has (perhaps unconsciously) created.
There is another option: the belief that both ideals and "reality" exist. Dualists commonly argue that the distinction between the mind (or 'ideas') and matter can be proven by employing Leibniz' principle of the identity of indiscernibles which states that if two things share exactly the same qualities, then they must be identical, as in indistinguishable from each other and therefore one and the same thing. Dualists then attempt to identify attributes of mind that are lacked by matter (such as privacy or intentionality) or vice versa (such as having a certain temperature or electrical charge). One notable application of the identity of indiscernibles was by René Descartes in his Meditations on First Philosophy. Descartes concluded that he could not doubt the existence of himself (the famous cogito ergo sum argument), but that he could doubt the (separate) existence of his body. From this, he inferred that the person Descartes must not be identical to the Descartes body since one possessed a characteristic that the other did not: namely, it could be known to exist. Solipsism agrees with Descartes in this aspect, and goes further: only things that can be known to exist for sure should be considered to exist. The Descartes body could only exist as an idea in the mind of the person Descartes. Descartes and dualism aim to prove the actual existence of reality as opposed to a phantom existence (as well as the existence of God in Descartes' case), using the realm of ideas merely as a starting point, but solipsism usually finds those further arguments unconvincing. The solipsist instead proposes that his/her own unconscious is the author of all seemingly "external" events from "reality".
The World as Will and Representation is the central work of Arthur Schopenhauer. Schopenhauer saw the human will as our one window to the world behind the representation, the Kantian thing-in-itself. He believed, therefore, that we could gain knowledge about the thing-in-itself, something Kant said was impossible, since the rest of the relationship between representation and thing-in-itself could be understood by analogy as the relationship between human will and human body.
The idealist philosopher George Berkeley argued that physical objects do not exist independently of the mind that perceives them. An item truly exists only as long as it is observed; otherwise, it is not only meaningless but simply nonexistent. The observer and the observed are one. Berkeley does attempt to show things can and do exist apart from the human mind and our perception, but only because there is an all-encompassing Mind in which all "ideas" are perceived – in other words, God, who observes all. Solipsism agrees that nothing exists outside of perception, but would argue that Berkeley falls prey to the egocentric predicament – he can only make his own observations, and thus cannot be truly sure that this God or other people exist to observe "reality". The solipsist would say it is better to disregard the unreliable observations of alleged other people and rely upon the immediate certainty of one's own perceptions.
Rationalism is the philosophical position that truth is best discovered by the use of reasoning and logic rather than by the use of the senses (see Plato's theory of Forms). Solipsism is also skeptical of sense-data.
The theory of solipsism crosses over with the theory of the philosophical zombie in that all other seemingly conscious beings actually lack true consciousness, instead they only display traits of consciousness to the observer, who is the only conscious being there is.
One critical test is nevertheless to consider the induction from experience that the externally observable world does not seem, at first approach, to be directly manipulable purely by mental energies alone. One can indirectly manipulate the world through the medium of the physical body, but it seems impossible to do so through pure thought (e.g. via psychokinesis). It might be argued that if the external world were merely a construct of a single consciousness, i.e. the self, it could then follow that the external world should be somehow directly manipulable by that consciousness, and if it is not, then solipsism is false. An argument against this states the notion that such manipulation may be possible but barred from the conscious self via the subconscious self, a 'locked' portion of the mind that is still nevertheless the same mind. Lucid dreaming might be considered an example of when these locked portions of the subconscious become accessible. An argument against this might be brought up in asking why the subconscious mind would be locked. Also, the access to the autonomous ('locked') portions of the mind during the lucid dreaming is obviously much different (for instance: is relatively more transient) than the access to autonomous regions of the perceived nature.
The method of the typical scientist is materialist: they first assume that the external world exists and can be known. But the scientific method, in the sense of a predict-observe-modify loop, does not require the assumption of an external world. A solipsist may perform a psychological test on themselves, to discern the nature of the reality in their mind - however David Deutsch uses this fact to counter-argue: "outer parts" of solipsist, behave independently so they are independent for "narrowly" defined (conscious) self. A solipsist's investigations may not be proper science, however, since it would not include the co-operative and communitarian aspects of scientific inquiry that normally serve to diminish bias.
Solipsism is a form of logical minimalism. Many people are intuitively unconvinced of the nonexistence of the external world from the basic arguments of solipsism, but a solid proof of its existence is not available at present. The central assertion of solipsism rests on the nonexistence of such a proof, and strong solipsism (as opposed to weak solipsism) asserts that no such proof can be made. In this sense, solipsism is logically related to agnosticism in religion: the distinction between believing you do not know, and believing you could not have known.
However, minimality (or parsimony) is not the only logical virtue. A common misapprehension of Occam's Razor has it that the simpler theory is always the best. In fact, the principle is that the simpler of two theories of equal explanatory power is to be preferred. In other words: additional "entities" can pay their way with enhanced explanatory power. So the realist can claim that, while his world view is more complex, it is more satisfying as an explanation.
The earliest reference to Solipsism in Hindu philosophy is found in the Brihadaranyaka Upanishad, dated to early 1st millennium BCE. The Upanishad holds the mind to be the only god and all actions in the universe are thought to be a result of the mind assuming infinite forms. After the development of distinct schools of Indian philosophy, Advaita Vedanta and Samkhya schools are thought to have originated concepts similar to solipsism.
Advaita is one of the six most known Hindu philosophical systems and literally means "non-duality". Its first great consolidator was Adi Shankaracharya, who continued the work of some of the Upanishadic teachers, and that of his teacher's teacher Gaudapada. By using various arguments, such as the analysis of the three states of experience—wakefulness, dream, and deep sleep, he established the singular reality of Brahman, in which Brahman, the universe and the Atman or the Self, were one and the same.
One who sees everything as nothing but the Self, and the Self in everything one sees, such a seer withdraws from nothing. For the enlightened, all that exists is nothing but the Self, so how could any suffering or delusion continue for those who know this oneness?— Ishopanishad: sloka 6, 7
The concept of the Self in the philosophy of Advaita could be interpreted as solipsism. However, the transhuman, theological implications of the Self in Advaita protect it from true solipsism as found in the west. Similarly, the Vedantic text Yogavasistha, escapes charge of solipsism because the real "I" is thought to be nothing but the absolute whole looked at through a particular unique point of interest.
Advaita is also thought to strongly diverge from solipsism in that, the former is a system of exploration of one's mind in order to finally understand the nature of the self and attain complete knowledge. The unity of existence is said to be directly experienced and understood at the end as a part of complete knowledge. On the other hand, solipsism posits the non-existence of the external world right at the beginning, and says that no further inquiry is possible.
Samkhya philosophy, which is sometimes seen as the basis of Yogic thought, adopts a view that matter exists independently of individual minds. Representation of an object in an individual mind is held to be a mental approximation of the object in the external world. Therefore, Samkhya chooses representational realism over epistemological solipsism. Having established this distinction between the external world and the mind, Samkhya posits the existence of two metaphysical realities Prakriti (matter) and Purusha (consciousness).
Some misinterpretations of Buddhism assert that external reality is an illusion, and sometimes this position is [mis]understood as metaphysical solipsism. Buddhist philosophy, though, generally holds that the mind and external phenomena are both equally transient, and that they arise from each other. The mind cannot exist without external phenomena, nor can external phenomena exist without the mind. This relation is known as "dependent arising" (pratityasamutpada).
The Buddha stated, "Within this fathom long body is the world, the origin of the world, the cessation of the world and the path leading to the cessation of the world". Whilst not rejecting the occurrence of external phenomena, the Buddha focused on the illusion created within the mind of the perceiver by the process of ascribing permanence to impermanent phenomena, satisfaction to unsatisfying experiences, and a sense of reality to things that were effectively insubstantial.
Mahayana Buddhism also challenges the illusion of the idea that one can experience an 'objective' reality independent of individual perceiving minds.
From the standpoint of Prasangika (a branch of Madhyamaka thought), external objects do exist, but are devoid of any type of inherent identity: "Just as objects of mind do not exist [inherently], mind also does not exist [inherently]". In other words, even though a chair may physically exist, individuals can only experience it through the medium of their own mind, each with their own literal point of view. Therefore, an independent, purely 'objective' reality could never be experienced.
The Yogacara (sometimes translated as "Mind only") school of Buddhist philosophy contends that all human experience is constructed by mind. Some later representatives of one Yogacara subschool (Prajnakaragupta, Ratnakīrti) propounded a form of idealism that has been interpreted as solipsism. A view of this sort is contained in the 11th-century treatise of Ratnakirti, "Refutation of the existence of other minds" (Santanantara dusana), which provides a philosophical refutation of external mind-streams from the Buddhist standpoint of ultimate truth (as distinct from the perspective of everyday reality).
In addition to this, the Bardo Thodol, Tibet's famous book of the dead, repeatedly states that all of reality is a figment of one's perception, although this occurs within the "Bardo" realm (post-mortem). For instance, within the sixth part of the section titled "The Root Verses of the Six Bardos", there appears the following line: "May I recognize whatever appeareth as being mine own thought-forms"; there are many lines in similar ideal.
A centered world, according to David Kellogg Lewis, consists of (1) a possible world, (2) an agent in that world, and (3) a time in that world. The concept of centered worlds has epistemic as well as metaphysical uses; for the latter, the three components of a centered world have connections to theories such as actualism, solipsism (especially egocentric presentism and perspectival realism), and presentism, respectively.David Bell (philosopher)
David Andrew Bell (born 1947) is a British philosopher. He is emeritus professor of philosophy at the University of Sheffield, He studied in Dublin (Trinity College), Göttingen (Georg-August Universität) and Canada (McMaster University), and is best known for his work on the philosophers Gottlob Frege, Immanuel Kant, and Edmund Husserl, and also on topics such as solipsism, phenomenology, the theory of thought and judgement, and the history of the Analytic Tradition.
Bell's awards include: Radcliffe Research Fellowship (1986–87); Alexander von Humboldt Research Fellowship (1988); British Academy Research Readership (1993); and the Alexander von Humboldt Prize in Philosophy (1995). He has held the posts of Visiting Professor, Institute of Philosophy, University of Leuven, (1987); Honorary Professor, University of Keele (1993–96); and Visiting Professor, Ludwig Maximillians Universität München (1994) He was a Fellow of the Wissenschaftskolleg zu Berlin [Institute of Advanced Study] (1995–96). And in 2001-2 he was President of the Mind Association.Bell has been influential in seeking to integrate the Analytic (predominantly anglophone) and the Continental (mainly French and German) traditions in philosophy. In 1993, together with Mark Sacks, he was instrumental in founding a new journal, The European Journal of Philosophy with the aim of proving 'a platform to which those both inside and outside Europe can turn to find some of the diversity ... in European philosophy', and thus overcome the insularity and at times hostility that has characterized aspects of that philosophy during the last century. In 2015 the EJP was voted among the top 20 philosophy journals world-wide. In 1999 Bell published an influential study of Husserl, in which analytic techniques were applied to a central figure of continental phenomenology.Epistemological solipsism
Epistemological solipsism is the view that one can only be sure of the existence of ones mind. The existence of other minds and the external world is not necessarily rejected but one can not be sure of its existence.Ethical solipsism
Ethical solipsism is relative to Ethical egoism; however, the difference is in that while the ethical egoist thinks that others should abide by the social order while it is in his/her best interest to do what best suits him/her as an individual, the Ethical Solipsist is of the belief that no other moral judgment exists or matters outside of his own individual moral judgment.Harry Kipling
Harry Kipling is a comics character appearing in the British weekly anthology 2000 AD, created by Simon Spurrier and Boo Cook. He is a True Brit, trying to survive in a world of rampant Pantheistic solipsism aided only by strong tea and a big gun.Index of philosophy of mind articles
This is a list of philosophy of mind articles.
Association for the Scientific Study of Consciousness
Brain in a vat
C. D. Broad
Critical realism (philosophy of perception)
David Hartley (philosopher)
David Kellogg Lewis
David Malet Armstrong
Direction of fit
Disquisitions relating to Matter and Spirit
Donald Davidson (philosopher)
Dualism (philosophy of mind)
Exclusion principle (philosophy)
Frank Cameron Jackson
Functionalism (philosophy of mind)
G. E. M. Anscombe
Georg Henrik von Wright
George Edward Moore
Hard problem of consciousness
Internalism and externalism
J. J. C. Smart
John Perry (philosopher)
Kenneth Allen Taylor
Mad pain and Martian pain
Michael Tye (philosopher)
Multiple Drafts Model
Naming and Necessity
Philosophy of artificial intelligence
Philosophy of mind
Philosophy of perception
Problem of other minds
Representational theory of mind
Society of Mind
The Concept of Mind
The Meaning of Meaning
William JamesList of philosophies
Philosophies: particular schools of thought, styles of philosophy, or descriptions of philosophical ideas attributed to a particular group or culture - listed in alphabetical order.Metaphysical solipsism
Metaphysical solipsism is the variety of idealism which asserts that nothing exists externally to this one mind, and since this mind is the whole of reality then the "external world" was never anything more than an idea. It can also be expressed by the assertion "there is nothing external to these present experiences", in other words, no reality exists beyond whatever is presently being sensed. The aforementioned definition of solipsism entails the non-existence of anything presently unperceived including the external world, causation, other minds (including God's mind or a subconscious mind), the past or future, and a subject of experience. Despite their ontological non-existence, these entities may nonetheless be said to "exist" as useful descriptions of the various experiences and thoughts that constitute 'this' mind. The solipsistic self is described by Wittgenstein in the Tractatus: "The self of solipsism shrinks to a point without extension and there remains the reality co-ordinated with it" (TLP 5.64).
There are weaker versions of metaphysical solipsism, such as Caspar Hare's egocentric presentism (or perspectival realism), in which other persons are conscious but their experiences are simply not present. Similarly, J. J. Valberg develops a concept of one's personal horizon and discusses how it is in a sense the (preeminent) horizon, stating that "we are all solipsists" in his sense of solipsism.Methodological solipsism
In epistemology and the philosophy of mind, methodological solipsism has at least two distinct definitions:
Methodological solipsism is the epistemological thesis that the individual self and its states are the sole possible or proper starting point for philosophical construction (Wood, 295). A skeptical turn along these lines is Cartesian skepticism.
Methodological solipsism is the thesis that the mental properties or mental states of an organism can be individuated exclusively on the basis of that state or property's relations with other internal states of the organism itself, without any reference to the society or the physical world in which the organism is embedded.The second definition was promoted by Jerry Fodor (1980). He later went on to distinguish this thesis from another that he called methodological individualism. Fodor's motivation for introducing these concepts into the philosophical (and now psychological) lexicon was the need to defend some sort of internalist conception of the mental from the problems posed by the famous "Twin Earth" thought experiment of Hilary Putnam. Very briefly, the question is whether it is possible for two people, one living in the actual world where water is H2O and the other living in some possible world (Twin Earth) where water has all the same qualities of our water but is actually composed of XYZ, to have the same beliefs (or other propositional attitudes) about water. The externalist says that this is not possible, while the internalist insists that it is.
Fodor defines methodological solipsism as the extreme position that states that the content of someone's beliefs about, say, water has absolutely nothing to do with the substance water in the outside world, nor with the commonly accepted definition of the society in which that person lives. Everything is determined internally. Moreover, the only thing that other people have to go on in ascribing beliefs to someone else are the internal states of his or her physical brain.
In contrast, Fodor defines methodological individualism as the view that mental states have a semantically evaluable character—that is, they are relational states. The relation that provides semantic meaning can be a relation with the external world or with one's culture and, so long as the relation produces some change in the causal power of a mental state, it can be considered to be a partial determinant of that state.Nihilism
Nihilism (; from Latin nihil, meaning 'nothing') is the philosophical viewpoint that suggests the denial or lack of belief towards the reputedly meaningful aspects of life. Most commonly, nihilism is presented in the form of existential nihilism, which argues that life is without objective meaning, purpose, or intrinsic value. Moral nihilists assert that there is no inherent morality, and that accepted moral values are abstractly contrived. Nihilism may also take epistemological, ontological, or metaphysical forms, meaning respectively that, in some aspect, knowledge is not possible, or reality does not actually exist.
The term is sometimes used in association with anomie to explain the general mood of despair at a perceived pointlessness of existence that one may develop upon realising there are no necessary norms, rules, or laws.Nihilism has also been described as conspicuous in or constitutive of certain historical periods. For example, Jean Baudrillard and others have called postmodernity a nihilistic epoch and some religious theologians and figures of religious authority have asserted that postmodernity and many aspects of modernity represent a rejection of theism, and that such rejection of theistic doctrine entails nihilism.Objectification
In social philosophy, objectification is the act of treating a person, or sometimes an animal, as an object or a thing. It is part of dehumanization, the act of disavowing the humanity of others. Sexual objectification, the act of treating a person as a mere object of sexual desire, is a subset of objectification, as is self-objectification, the objectification of one's self. In Marxism, the objectification of social relationships is discussed as "reification".Philosophical realism
In metaphysics, realism about a given object is the view that this object exists in reality independently of our conceptual scheme. In philosophical terms, these objects are ontologically independent of someone's conceptual scheme, perceptions, linguistic practices, beliefs, etc.
Realism can be applied to many philosophically interesting objects and phenomena: other minds, the past or the future, universals, mathematical entities (such as natural numbers), moral categories, the physical world, and thought.
Realism can also be a view about the nature of reality in general, where it claims that the world exists independent of the mind, as opposed to non-realist views (like some forms of skepticism and solipsism, which question our ability to assert the world is independent of our mind). Philosophers who profess realism often claim that truth consists in a correspondence between cognitive representations and reality.Realists tend to believe that whatever we believe now is only an approximation of reality but that the accuracy and fullness of understanding can be improved. In some contexts, realism is contrasted with idealism. Today it is more usually contrasted with anti-realism, for example in the philosophy of science.
The oldest use of the term "realism" appears in medieval scholastic interpretations and adaptations of ancient Greek philosophy.Problem of other minds
The problem of other minds is a philosophical problem traditionally stated as the following epistemological challenge raised by the skeptic: Given that I can only observe the behavior of others, how can I know that others have minds? It is a central issue of the philosophical idea known as solipsism: the notion that for any person only one's own mind is known to exist. Solipsism maintains that no matter how sophisticated someone's behavior is, behavior on its own does not guarantee the presence of mentality.Self-refuting idea
Self-refuting ideas or self-defeating ideas are ideas or statements whose falsehood is a logical consequence of the act or situation of holding them to be true. Many ideas are called self-refuting by their detractors, and such accusations are therefore almost always controversial, with defenders stating that the idea is being misunderstood or that the argument is invalid. For these reasons, none of the ideas below are unambiguously or incontrovertibly self-refuting. These ideas are often used as axioms, which are definitions taken to be true (tautological assumptions), and cannot be used to test themselves, for doing so would lead to only two consequences: consistency (circular reasoning) or exception (self-contradiction). It is important to know that the conclusion of an argument that is self-refuting is not necessarily false, since it could be supported by another, more valid, argument.Simulated consciousness in fiction
Simulated consciousness, synthetic consciousness, etc. is a theme of a number of works in science fiction. The theme is one step beyond the concept of the "brain in a vat"/"simulated reality" in that not only the perceived reality but the brain and its consciousness are simulations themselves.
Stanislaw Lem's professor Corcoran (met by Ijon Tichy during his interstellar travels, first published by Lem in 1961) simulated conscious agents (personoids) to actually test the viability of the "simulation hypothesis" of the reality, i.e., the idea of solipsism.In the 1954 story The Tunnel under the World by Frederik Pohl, a whole city was simulated in order to run tests of the efficiency of advertising campaigns, and the plot evolves from the point when one "simulacrum" suddenly notices that every day is June 15. Pohl's idea was elaborated in Simulacron-3 (1964) by Daniel F. Galouye (alternative title: Counterfeit World), which tells the story of a virtual city developed as a computer simulation for market research purposes. In this city the simulated inhabitants possess consciousness; all but one of the inhabitants are unaware of the true nature of their world.Furthermore, various novels by Greg Egan such as Permutation City (1994), Diaspora (1997) and Schild's Ladder (2002) explore the concept of simulated consciousness.Solipsism syndrome
Solipsism syndrome refers to a psychological state in which a person feels that the world is not external to his or her mind. Periods of extended isolation may predispose people to this condition. In particular, the syndrome has been identified as a potential concern for individuals living in outer space for extended periods of time.Subjectivism
Subjectivism is the doctrine that "our own mental activity is the only unquestionable fact of our experience.", instead of shared or communal, and that there is no external or objective truth.
The success of this position is historically attributed to Descartes and his methodic doubt. Subjectivism accords primacy to subjective experience as fundamental of all measure and law. In extreme forms like Solipsism, it may hold that the nature and existence of every object depends solely on someone's subjective awareness of it. One may consider the qualified empiricism of George Berkeley in this context, given his reliance on God as the prime mover of human perception. Thus, subjectivism.To Sail Beyond the Sunset
To Sail Beyond the Sunset is a science fiction novel by American writer Robert A. Heinlein, published in 1987. It was the last novel published before his death in 1988. The title is taken from the poem Ulysses, by Alfred Lord Tennyson. The stanza of which it is a part, quoted by a character in the novel, is as follows:
It is the final part of the "Lazarus Long" cycle of stories, involving time travel, parallel dimensions, free love, voluntary incest, and a concept that Heinlein named pantheistic solipsism, or 'World as Myth': the theory that universes are created by the act of imagining them, so that somewhere (for example) the Land of Oz is real. Other books in the cycle include Methuselah's Children, Time Enough for Love, The Number of the Beast, and The Cat Who Walks Through Walls.