what is Solipsism?

Answer 1

The belief that only you exist. As you can actually see other people its usually the belief that other minds do not exist. Nobody really believes it but, like scepticism, you can use it to analyse other theories situations and puzzles.

Answer 2

Solipsism is the reduction of your existence to total isolation.

Skepticism is a route to solipsism. If you doubt anything you cannot concretely prove to be true you eventually realize that everything is probably an illusion. If that is the case you are essentially alone and nothing else matters. This is part of Descartes thought experiment that led to the statement Cogito Ergo Sum - I think therefore I am.

Answer 3

The word solipsism (Latin: solus, alone + ipse, self) is used for two related yet distinct concepts:

An epistemological position that one's own perceptions are the only things that can be known with certainty. The nature of the external world — that is, the source of one's perceptions; therefore cannot be conclusively known; it may not even exist. This is also called external world skepticism.
A metaphysical belief that the universe is entirely the creation of one's own mind. Thus, in a sense, the belief that nothing 'exists' outside of one's own mind.

Answer 4

Some wag said it is the hardest philosophy to which one can convert others. It says basically that only you are real. Other people and things exist only in your mind. Some people are so schizoid that they are practically solipsists. My oldest sister has become like that. I fear that I must have her sent to a hospital or jail, for she has caused much trouble for my kid sister and me.

Answer 5

The theory that self-existence is the only certainty; absolute egoism - the extreme form of subjective idealism.

Answer 6

The theory that the self is the only thing that can be known and verified.
The theory or view that the self is the only reality.
Enjoy
sunny

Answer 7

sol·ip·sism (slp-szm, slp-)

NOUN:
Philosophy
The theory that the self is the only thing that can be known and verified.
The theory or view that the self is the only reality.

--------------------------------------------------------------------------------
ETYMOLOGY:
Latin slus, alone; see s(w)e- in Indo-European roots + Latin ipse, self + -ism

OTHER FORMS:
solip·sist (Noun), solip·sistic (Adjective)

Answer 8

No idea search goggle

Answer 9

Solipsism is first recorded with the Greek presocratic sophist Gorgias (c. 483–375 BC) who is quoted by the Roman sceptic Sextus Empiricus as having stated:

Nothing exists-

Even if something exists, nothing can be known about it, and
Even if something could be known about it, knowledge about it can't be communicated to others
Epistemological solipsism is generally identified with statements 2 and 3 from Gorgias; metaphysical solipsism embraces all three.

Varieties of solipsism-

Metaphysical solipsism-
Metaphysical solipsism is the variety of idealism which maintains that the individual self of the solipsistic philosopher is the whole of reality and that the external world and other persons are representations of that self having no independent existence (Wood, 295).

Methodological solipsism-
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.

Questions about solipsism-

Is solipsism one or many?
Philosophical disputes about the character and the consequences of solipsism hinge on the questions of -
(1) whether there is anything approaching a rigorous definition of solipsism,
(2) whether a unique definition can be singled out as the one and only proper definition, or
(3) whether there are as many definitions of solipsism as there are solipsists.

Is solipsism falsifiable?
According to one argument, no experiment (by a given solipsist A) can be designed to disprove solipsism (to the satisfaction of that solipsist A). Solipsism is therefore said to be unfalsifiable in the sense in which Karl Popper used the word. A solipsistic viewpoint held by a particular individual is unfalsifiable only to that individual, however. Any other person B might by introspection (cogito, ergo sum) conclude that he or she (B) does in fact exist and therefore that A is proven wrong (though B might symmetrically doubt whether A exists, and therefore would not have disproven solipsism per se, only solipsism by A). Even though B has proven A wrong, there is no way for B to validly convince A to abandon solipsism, since A doubts B's very existence, let alone B's experiences or experimental results.

Is solipsism plausible?
At least two objections have been proposed to the solipsist position. One is technical and involves dissection of the concept. The other asks a common sense question the answer to which would be highly implausible if solipsism were correct.

1) The technical approach: Perception is the faculty of awareness. A faculty is an attribute. Attributes do not exist apart from the entity or entities that have that characteristic. Hence perception requires an existent entity with that faculty, thus contradicting the solipsist premise that only perception exists.

2) The common sense approach: The solipsist position that only one's personal perception exists requires one to hold that all the creations of which one is aware were created within one's own perceptual functioning. Thus the plays of Shakespeare, the symphonies of Beethoven and Mozart, Maxwell's Equations and the theory of Relativity, the theorems of Calculus and higher mathematics, and so forth were created by one's own perceptual operations.

A third objection could be termed a corollary to the two above. It asks a question about the functioning of one's personal perceptions. The solipsist cannot deny the fact that he thinks, goes through reasoning processes about his perceptions. His consciousness is not just perceptions; it's also thinking about them. How is this possible w/o some mental machinery which can perform such? But if such mental machinery exists independent and apart from his perceptions, this also contradicts the "perceptions only" premise.

Thought experiments-

Brain in a vat
A thought-experiment related to solipsism is the brain in a vat. The person performing the thought-experiment considers the possibility that they are trapped within some utterly unknowable reality, much like that illustrated in the movie The Matrix. A mad scientist could be sending the same impulses to one's brain in a vat that one's brain (understood to be that of a person in the "real world") might receive, thereby creating "the world" as one knows it from the mad scientist's program. Yet, for one's brain in the vat, that "world" would obviously not be "real." This raises the possibility that everything one thinks or knows is illusion. Or, at the least, that one cannot know with any certainty whether one's brain is in the "real world" or in a vat receiving impulses that would create an equivalent consciousness— or even if there is a real world, mad scientist, brain, or vat. This also can be connected to Descartes "Meditations" In that he supposes that all of reality and his senses are merely being invoked by God, but though the example is the same under different circumstances, Descartes only used this Solipism example so that he might prove it wrong.

Sole surviving soul-
Would the last person left alive after a nuclear holocaust be a solipsist? Not necessarily, because for the solipsist, it is not merely the case that they believe that their thoughts, experiences, and emotions are, as a matter of contingent fact, the only thoughts, experiences, and emotions that can be. Rather, the solipsist can attach no meaning to the supposition that there could be thoughts, experiences, and emotions other than their own — that events may occur or objects or people exist independently of the solipsist's own experiences. In short, the metaphysical solipsist understands the word "pain", for example, to mean "one's own [i.e., someone's] pain" — but this word cannot accordingly be construed to apply in any sense other than this exclusively egocentric, non-empathetic one.

Assuming the validity of solipsism, one must infer that it makes as much or as little sense, on these premises, to attribute any psychological predicate to another human being as it does to attribute it to a table or a rock. Thus on these premises, it makes no sense to attribute consciousness to another human being at all, whether or not he's the last man on Earth. A non-solipsistic 'last man alive' would not believe that tenet if he suddenly stumbled across another human being (or simply recalled one from memory). (Thornton 2006).

Hutton's Paradox-

An intriguing paradox concerning solipsism was described by the British writer Eric Bond Hutton in 1989.[1] As a child Hutton often had lucid dreams in which people and things seemed as solid and real as in waking life. This led him to wonder whether life itself was a dream, even whether he existed only in somebody else's dream. Once in a while he would have a pre-lucid dream (in which one suspects that one is dreaming). He always found these somewhat disturbing, but one day hit upon a magic formula to be used in them: "If I find myself asking 'Am I dreaming?' it proves that I am, since this question would never occur to me in waking life." Yet, such is the nature of dreams, he could never recall it when he needed to. Many years later, when he came to write about his childhood fascination with dreams, he was struck by a contradiction in his earlier reasoning. True, asking oneself "Am I dreaming?" would seem to prove that one is, since one does not ask oneself that question in waking life. And yet he had often done precisely that. So what was he to conclude? That it does not prove one is dreaming? Or that life really is a dream?

Similar in nature, though not involving any paradox, is Zhuangzi's Dream. Zhuangzi, the ancient Chinese philosopher, once had a vivid dream in which he was a butterfly, fluttering happily here and there. Suddenly he woke up, but afterward was never certain whether he was a man who once dreamt he was a butterfly or a butterfly dreaming he was a man.

Solipsism in epistemology-

The foundations of solipsism lie at the heart of the view that the individual understands all psychological concepts (thinking, willing, perceiving, etc.) by 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 held by a great many, if not indeed the majority of, philosophers, since Descartes elevated the egocentric search for incontrovertible certainty to the status of the primary goal of critical epistemology. In this sense, then, it is at least arguable that epistemological solipsism is implicit in many philosophies of knowledge and mind since Descartes, and that any philosophy which adopts the Cartesian egocentric approach as its basic frame of reference is inherently solipsistic.

The problem of solipsism also merits close examination because it is based upon three widely held philosophical presuppositions, which are themselves fundamental and wide-ranging in importance.
These are:
(1) That my most certain knowledge is the contents of my own mind — my thoughts, experiences, affects, etc.;
(2) That there is no conceptual or logically necessary link between the mental and the physical — between, say, the occurrence of certain conscious experiences or mental states and the 'possession' and behavioral dispositions of a 'body' of a particular kind (see the above thought experiment); and
(3) That the experiences of a given person are necessarily private to that person. These presuppositions are unmistakably Cartesian in origin, and are very widely accepted by philosophers and non-philosophers alike.

Solipsism in relation to other philosophies-

Idealism and materialism-
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 cold reality of atoms and energy. Materialism posits a separate 'world out there' that can be touched and felt, with the separate individual's physical and mental experiences reducible to the collisions of atoms and the interactions of firing neurons. The only thing that dreams and hallucinations prove are that some neurons can misfire and malfunction, but there is no fundamental reality behind an idea except as a brain-state. Idealists, on the other hand, believe that the mind and its thoughts are the only true things that exist. This doctrine is often called Platonism after its most famous proponent. The material world is ephemeral, but a perfect triangle or "love" 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 tends toward extreme idealism. Thoughts and concepts are all that exist, and furthermore, only 'my' thoughts and consciousness exist. The so-called "reality" is nothing more than an idea that the solipsist has (perhaps unconsciously) created.

Cartesian dualism-

There is another option, of course: 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's principle of the identity of indiscernibles. This states that two things are identical if, and only if, they share exactly the same qualities, that is, are indistinguishable. 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).[8] [9] 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[10][11] Descartes and dualism go on to prove the actual existence of reality as opposed to a phantom existence (as well as the existence of God in Descartes's case), using the realm of ideas merely as a starting point, but solipsism usually finds those further arguments unconvincing. The solipsist instead proposes that their own unconscious is the author of all seemingly "external" events from "reality".

Radical empiricism-

The idealist philosopher George Berkeley argued that so-called physical objects do not exist independently of the so-called mind that perceives them. An item truly exists only so 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. The solipsist appreciates the fact that nothing exists outside of perception, but would further point out that Berkeley falls prey to the egocentric predicament - he can only make his own observations, and can't be truly sure that this God or other people exist to observe "reality". The solipsist would say it is better to disregard the unreliable possible observations of alleged other people and rely upon the immediate certainty of one's own perceptions. [12][13]

Pantheism-

While solipsism is not generally compatible with traditional views of God, it is somewhat related to Pantheism, the belief that everything is God and part of God. The difference is usually a matter of focus. The pantheist would tend to identify themselves with being a part of everything in reality, which is actually all God beneath the surface. For instance, many ancient Indian philosophies advocate the notion that all matter (and thus humans) is subtly interconnected with not only our immediate surroundings, but with everything in the universe; that all we can perceive is a kind of vision, Samsara. The solipsist, however, would be more likely to put themselves squarely in the center as the only item of reality, with all other beings in reality illusions. It could be said to be another naming dispute; "The Universe" / "God" for the pantheist is "My Unconscious Mind" / "Me" for the solipsist.

Bishop Berkeley muttered darkly:
"If I can't see you, you can't be you."

Eastern philosophies-
Thoughts somewhat similar to solipsism are present in much of eastern philosophy. Taoism and several interpretations of Buddhism, especially Zen, teach that drawing a distinction between self and universe is nonsensical and arbitrary, and merely an artifact of language rather than an inherent truth.

Hinduism-
"He who sees everything as nothing but the Self, and the Self in everything he 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?"

Isha Upanishad; sloka 6, 7-

The philosophy of Vedanta which says "Aham Brahamam", roughly translated as "I am the Absolute Truth", is truly nothing but solipsism in its sincerest sense. The "real" world is but an illusion in the mind of the observer. When the solipsist understands the "maya" or illusion of world, then he escapes the mundane and reaches the state of everlasting bliss.

Buddhism-
Some later representatives of one Yogacara subschool (Prajnakaragupta, Ratnakirti) were proponents of extreme illusionism and solipsism (as well as of solipsism of this moment). The best example of such extreme ideas was the treatise of Ratnakirti (XI century) "Refutation of the existence of other minds" (Santanantara dusana).

[It is important to note that all mentioned Yogacara trends are not purely philosophical but religious—philosophical. All Yogacara discourse takes place within the religious and doctrinal dimension of Buddhism. It is also determined by the fundamental Buddhist problem, that is living being and its liberation from the bondage of Samsara.]

Objections-
The following are some common critiques and responses about solipsism:

People die-
But the solipsist himself or herself is not dead. If somebody else dies, the supposed being who has supposedly "died" is only a phantom of the solipsist's imagination anyway, and the elimination of that phantom proves nothing. A critic would point out that many (self-proclaimed) solipsists have died in the history of the world, and solipsism hasn't disappeared yet. However, the solipsist would respond that he or she has not died, and therefore his or her solipsism is not yet disproved. He or she never believed in the existence of those other solipsists in the first place.
The applicability of the past
The fact that an individual may find a statement such as "I think, therefore I am" applicable to them, yet not originating in their mind indicates that others have had a comparable degree of insight into their own mental processes, and that these are similar enough to the subject's. Further, existence in complete unity with reality means that learning is impossible -- one would have to have awareness of all things. The metaphysical solipsist would respond that, much like other people are products of his own mind, so, too, is "the past" and its attendant information. Thus, "I think, therefore I am" would indeed have originated in their mind.

Life is imperfect-
Why would a solipsist create things such as pain and loss for his or her self? More generally, it might be asked "If the world is completely in my head, how come I don't live the most fantastic life imaginable?" One response would be to simply plead ignorance and note that there may be some reason which was forgotten on purpose. Another response is that categories such as 'pain' are perceptions assumed with all of the other socio-cultural human values that the solipsist has created for himself - a package deal, so to speak (Khashaba 2002). More creatively, perhaps this is all out of a desire to avoid being bored, or perhaps even that the solipsist is in fact living the most perfect life he or she could imagine. This issue is somewhat related to theodicy, the "problem of evil", except that the solipsist himself is the all-powerful God who has somehow allowed imperfection into his world. A solipsist may also counter that since he never made himself he never had a choice in the way his mind operates and appears to have only limited control over how his experiences evolve. He could also conclude that the world of his own mind's creation is the exact total of all his desires, conscious and otherwise and that each moment is always perfect in the sense that it would not be other than his own mind in total had made.

Solipsism undercuts morality-
If solipsism is true, then practically all standards for moral behavior would seem to be meaningless, according to this argument. There is no God, so that basis for morality is gone, but even secular humanism becomes meaningless since there are no such things as other humans. Everything and everyone else is just a figment of imagination, so there's no particular reason not to make these figments disappear by, say, mass annihilation. The subconscious mind could always imagine them back to life, if that's what's really wanted, anyway. The problem with this argument is that it falls prey to the Appeal to Consequences Fallacy; if solipsism is true, then it doesn't matter that it has unfortunate implications. This can possibly be countered by people who believe that (a non-solipsist) morality is an inherent part of the universe that can be proved to exist. A solipsist may also understand that everything being a part of himself would also mean that harming anything would be harming himself with associated negative consequences such as pain. Or a solipsist might say that harming others is imprudent because the solipsist can only be uncertain of their real existence.
The practical solipsist needs a language to formulate his or her thoughts about solipsism
Language is an essential tool to communicate with other minds. Why does a solipsist universe need a language? Indeed, one might even say, solipsism is necessarily incoherent, for to make an appeal to logical rules or empirical evidence the solipsist would implicitly have to affirm the very thing in which he or she purportedly refuses to believe: the 'reality' of intersubjectively valid criteria, and/or of a public, extra-mental world.A possible response would be that to keep from becoming bored, perhaps the solipsist imagines "other" minds, which would actually be only elements of his own mind. He or she has chosen to forget control of these minds for the time being, and the elaborate languages required for interaction with these more isolated segments of his mind are merely part of the creation of "reality." As for the rules of logic, they are probably merely an artefact of the peculiar psychology of the solipsist and only appear to exist in the "real" world. Greg Egan addressed this issue in his story "Dust" and the subsequent novel based on the story Permutation City by demonstrating that the solipsist can choose to develop his own self-consistent logical system apart from "reality". A more telling question might be, why does the solipsist need to invent so many and such a variety of languages? There is of course E-prime which strives to speak from the personal point of view and seems ideally suited for solipsism.

Realism vs. solipsism-
An objection, raised by David Deutsch, among others, is that since the solipsist has no control over the "universe" he is creating for himself, there must be some unconscious part of his mind creating it. If the solipsist makes his unconscious mind the object of scientific study (e.g., by conducting experiments), he will find that it behaves with the same complexity as the universe offered by realism; therefore, the distinction between realism and solipsism collapses. What realism calls "the universe", solipsism calls "one's unconscious mind." But these are just different names for the same thing. Both are massively complex processes other than the solipsist's conscious mind, and the cause of all the solipsist's experiences; possibly merely a labelling distinction. Application of Occam's Razor might then suggest that postulating the existence of 'reality' may be a simpler solution than a massive unconscious mind. The solipsist would claim that the apparent independence of real world events just shows how good his unconscious mind is at maintaining the illusion. The realist's world may be every bit as complex as the solipsist's unconscious, but when the solipsist dies, the entire universe will cease to exist. (See also, Le Guin, Ursula K. Lathe of Heaven Eos; Reprint edition (April 1, 1997))

Philosophical poverty-
Some philosophers hold the viewpoint that solipsism is entirely empty and without content. Like a 'faith' argument, it seems sterile, i.e., allows no further argument, nor can it be falsified. The world remains absolutely the same— so where could a solipsist go from there? Viewed in this way, solipsism seems only to have found a facile way to avoid the more difficult task of a critical analysis of what is 'real' and what isn't, and what 'reality' means. Some might say Solipsism is not impoverished because it helps philosophers operate from a principle of doubt because their difficult task can only determine the probability of what is real and what isn't. The solipsist would hold that further argument is meaningless and there are limits to what can be known about 'reality.'

Answer 10

Origin of solipsism-

Solipsism is first recorded with the Greek presocratic sophist Gorgias (c. 483–375 BC) who is quoted by the Roman sceptic Sextus Empiricus as having stated:

Nothing exists-

Even if something exists, nothing can be known about it, and
Even if something could be known about it, knowledge about it can't be communicated to others
Epistemological solipsism is generally identified with statements 2 and 3 from Gorgias; metaphysical solipsism embraces all three.

Varieties of solipsism-

Metaphysical solipsism-
Metaphysical solipsism is the variety of idealism which maintains that the individual self of the solipsistic philosopher is the whole of reality and that the external world and other persons are representations of that self having no independent existence (Wood, 295).

Methodological solipsism-
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.

Questions about solipsism-

Is solipsism one or many?
Philosophical disputes about the character and the consequences of solipsism hinge on the questions of -
(1) whether there is anything approaching a rigorous definition of solipsism,
(2) whether a unique definition can be singled out as the one and only proper definition, or
(3) whether there are as many definitions of solipsism as there are solipsists.

Is solipsism falsifiable?
According to one argument, no experiment (by a given solipsist A) can be designed to disprove solipsism (to the satisfaction of that solipsist A). Solipsism is therefore said to be unfalsifiable in the sense in which Karl Popper used the word. A solipsistic viewpoint held by a particular individual is unfalsifiable only to that individual, however. Any other person B might by introspection (cogito, ergo sum) conclude that he or she (B) does in fact exist and therefore that A is proven wrong (though B might symmetrically doubt whether A exists, and therefore would not have disproven solipsism per se, only solipsism by A). Even though B has proven A wrong, there is no way for B to validly convince A to abandon solipsism, since A doubts B's very existence, let alone B's experiences or experimental results.

Is solipsism plausible?
At least two objections have been proposed to the solipsist position. One is technical and involves dissection of the concept. The other asks a common sense question the answer to which would be highly implausible if solipsism were correct.

1) The technical approach: Perception is the faculty of awareness. A faculty is an attribute. Attributes do not exist apart from the entity or entities that have that characteristic. Hence perception requires an existent entity with that faculty, thus contradicting the solipsist premise that only perception exists.

2) The common sense approach: The solipsist position that only one's personal perception exists requires one to hold that all the creations of which one is aware were created within one's own perceptual functioning. Thus the plays of Shakespeare, the symphonies of Beethoven and Mozart, Maxwell's Equations and the theory of Relativity, the theorems of Calculus and higher mathematics, and so forth were created by one's own perceptual operations.

A third objection could be termed a corollary to the two above. It asks a question about the functioning of one's personal perceptions. The solipsist cannot deny the fact that he thinks, goes through reasoning processes about his perceptions. His consciousness is not just perceptions; it's also thinking about them. How is this possible w/o some mental machinery which can perform such? But if such mental machinery exists independent and apart from his perceptions, this also contradicts the "perceptions only" premise.

Thought experiments-

Brain in a vat
A thought-experiment related to solipsism is the brain in a vat. The person performing the thought-experiment considers the possibility that they are trapped within some utterly unknowable reality, much like that illustrated in the movie The Matrix. A mad scientist could be sending the same impulses to one's brain in a vat that one's brain (understood to be that of a person in the "real world") might receive, thereby creating "the world" as one knows it from the mad scientist's program. Yet, for one's brain in the vat, that "world" would obviously not be "real." This raises the possibility that everything one thinks or knows is illusion. Or, at the least, that one cannot know with any certainty whether one's brain is in the "real world" or in a vat receiving impulses that would create an equivalent consciousness— or even if there is a real world, mad scientist, brain, or vat. This also can be connected to Descartes "Meditations" In that he supposes that all of reality and his senses are merely being invoked by God, but though the example is the same under different circumstances, Descartes only used this Solipism example so that he might prove it wrong.

Sole surviving soul-
Would the last person left alive after a nuclear holocaust be a solipsist? Not necessarily, because for the solipsist, it is not merely the case that they believe that their thoughts, experiences, and emotions are, as a matter of contingent fact, the only thoughts, experiences, and emotions that can be. Rather, the solipsist can attach no meaning to the supposition that there could be thoughts, experiences, and emotions other than their own — that events may occur or objects or people exist independently of the solipsist's own experiences. In short, the metaphysical solipsist understands the word "pain", for example, to mean "one's own [i.e., someone's] pain" — but this word cannot accordingly be construed to apply in any sense other than this exclusively egocentric, non-empathetic one.

Assuming the validity of solipsism, one must infer that it makes as much or as little sense, on these premises, to attribute any psychological predicate to another human being as it does to attribute it to a table or a rock. Thus on these premises, it makes no sense to attribute consciousness to another human being at all, whether or not he's the last man on Earth. A non-solipsistic 'last man alive' would not believe that tenet if he suddenly stumbled across another human being (or simply recalled one from memory). (Thornton 2006).

Hutton's Paradox-

An intriguing paradox concerning solipsism was described by the British writer Eric Bond Hutton in 1989.[1] As a child Hutton often had lucid dreams in which people and things seemed as solid and real as in waking life. This led him to wonder whether life itself was a dream, even whether he existed only in somebody else's dream. Once in a while he would have a pre-lucid dream (in which one suspects that one is dreaming). He always found these somewhat disturbing, but one day hit upon a magic formula to be used in them: "If I find myself asking 'Am I dreaming?' it proves that I am, since this question would never occur to me in waking life." Yet, such is the nature of dreams, he could never recall it when he needed to. Many years later, when he came to write about his childhood fascination with dreams, he was struck by a contradiction in his earlier reasoning. True, asking oneself "Am I dreaming?" would seem to prove that one is, since one does not ask oneself that question in waking life. And yet he had often done precisely that. So what was he to conclude? That it does not prove one is dreaming? Or that life really is a dream?

Similar in nature, though not involving any paradox, is Zhuangzi's Dream. Zhuangzi, the ancient Chinese philosopher, once had a vivid dream in which he was a butterfly, fluttering happily here and there. Suddenly he woke up, but afterward was never certain whether he was a man who once dreamt he was a butterfly or a butterfly dreaming he was a man.

Solipsism in epistemology-

The foundations of solipsism lie at the heart of the view that the individual understands all psychological concepts (thinking, willing, perceiving, etc.) by 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 held by a great many, if not indeed the majority of, philosophers, since Descartes elevated the egocentric search for incontrovertible certainty to the status of the primary goal of critical epistemology. In this sense, then, it is at least arguable that epistemological solipsism is implicit in many philosophies of knowledge and mind since Descartes, and that any philosophy which adopts the Cartesian egocentric approach as its basic frame of reference is inherently solipsistic.

The problem of solipsism also merits close examination because it is based upon three widely held philosophical presuppositions, which are themselves fundamental and wide-ranging in importance.
These are:
(1) That my most certain knowledge is the contents of my own mind — my thoughts, experiences, affects, etc.;
(2) That there is no conceptual or logically necessary link between the mental and the physical — between, say, the occurrence of certain conscious experiences or mental states and the 'possession' and behavioral dispositions of a 'body' of a particular kind (see the above thought experiment); and
(3) That the experiences of a given person are necessarily private to that person. These presuppositions are unmistakably Cartesian in origin, and are very widely accepted by philosophers and non-philosophers alike.

Solipsism in relation to other philosophies-

Idealism and materialism-
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 cold reality of atoms and energy. Materialism posits a separate 'world out there' that can be touched and felt, with the separate individual's physical and mental experiences reducible to the collisions of atoms and the interactions of firing neurons. The only thing that dreams and hallucinations prove are that some neurons can misfire and malfunction, but there is no fundamental reality behind an idea except as a brain-state. Idealists, on the other hand, believe that the mind and its thoughts are the only true things that exist. This doctrine is often called Platonism after its most famous proponent. The material world is ephemeral, but a perfect triangle or "love" 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 tends toward extreme idealism. Thoughts and concepts are all that exist, and furthermore, only 'my' thoughts and consciousness exist. The so-called "reality" is nothing more than an idea that the solipsist has (perhaps unconsciously) created.

Cartesian dualism-

There is another option, of course: 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's principle of the identity of indiscernibles. This states that two things are identical if, and only if, they share exactly the same qualities, that is, are indistinguishable. 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).[8] [9] 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[10][11] Descartes and dualism go on to prove the actual existence of reality as opposed to a phantom existence (as well as the existence of God in Descartes's case), using the realm of ideas merely as a starting point, but solipsism usually finds those further arguments unconvincing. The solipsist instead proposes that their own unconscious is the author of all seemingly "external" events from "reality".

Radical empiricism-

The idealist philosopher George Berkeley argued that so-called physical objects do not exist independently of the so-called mind that perceives them. An item truly exists only so 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. The solipsist appreciates the fact that nothing exists outside of perception, but would further point out that Berkeley falls prey to the egocentric predicament - he can only make his own observations, and can't be truly sure that this God or other people exist to observe "reality". The solipsist would say it is better to disregard the unreliable possible observations of alleged other people and rely upon the immediate certainty of one's own perceptions. [12][13]

Pantheism-

While solipsism is not generally compatible with traditional views of God, it is somewhat related to Pantheism, the belief that everything is God and part of God. The difference is usually a matter of focus. The pantheist would tend to identify themselves with being a part of everything in reality, which is actually all God beneath the surface. For instance, many ancient Indian philosophies advocate the notion that all matter (and thus humans) is subtly interconnected with not only our immediate surroundings, but with everything in the universe; that all we can perceive is a kind of vision, Samsara. The solipsist, however, would be more likely to put themselves squarely in the center as the only item of reality, with all other beings in reality illusions. It could be said to be another naming dispute; "The Universe" / "God" for the pantheist is "My Unconscious Mind" / "Me" for the solipsist.

Bishop Berkeley muttered darkly:
"If I can't see you, you can't be you."

Eastern philosophies-
Thoughts somewhat similar to solipsism are present in much of eastern philosophy. Taoism and several interpretations of Buddhism, especially Zen, teach that drawing a distinction between self and universe is nonsensical and arbitrary, and merely an artifact of language rather than an inherent truth.

Hinduism-
"He who sees everything as nothing but the Self, and the Self in everything he 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?"

Isha Upanishad; sloka 6, 7-

The philosophy of Vedanta which says "Aham Brahamam", roughly translated as "I am the Absolute Truth", is truly nothing but solipsism in its sincerest sense. The "real" world is but an illusion in the mind of the observer. When the solipsist understands the "maya" or illusion of world, then he escapes the mundane and reaches the state of everlasting bliss.

Buddhism-
Some later representatives of one Yogacara subschool (Prajnakaragupta, Ratnakirti) were proponents of extreme illusionism and solipsism (as well as of solipsism of this moment). The best example of such extreme ideas was the treatise of Ratnakirti (XI century) "Refutation of the existence of other minds" (Santanantara dusana).

[It is important to note that all mentioned Yogacara trends are not purely philosophical but religious—philosophical. All Yogacara discourse takes place within the religious and doctrinal dimension of Buddhism. It is also determined by the fundamental Buddhist problem, that is living being and its liberation from the bondage of Samsara.]

Objections-
The following are some common critiques and responses about solipsism:

People die-
But the solipsist himself or herself is not dead. If somebody else dies, the supposed being who has supposedly "died" is only a phantom of the solipsist's imagination anyway, and the elimination of that phantom proves nothing. A critic would point out that many (self-proclaimed) solipsists have died in the history of the world, and solipsism hasn't disappeared yet. However, the solipsist would respond that he or she has not died, and therefore his or her solipsism is not yet disproved. He or she never believed in the existence of those other solipsists in the first place.
The applicability of the past
The fact that an individual may find a statement such as "I think, therefore I am" applicable to them, yet not originating in their mind indicates that others have had a comparable degree of insight into their own mental processes, and that these are similar enough to the subject's. Further, existence in complete unity with reality means that learning is impossible -- one would have to have awareness of all things. The metaphysical solipsist would respond that, much like other people are products of his own mind, so, too, is "the past" and its attendant information. Thus, "I think, therefore I am" would indeed have originated in their mind.

Life is imperfect-
Why would a solipsist create things such as pain and loss for his or her self? More generally, it might be asked "If the world is completely in my head, how come I don't live the most fantastic life imaginable?" One response would be to simply plead ignorance and note that there may be some reason which was forgotten on purpose. Another response is that categories such as 'pain' are perceptions assumed with all of the other socio-cultural human values that the solipsist has created for himself - a package deal, so to speak (Khashaba 2002). More creatively, perhaps this is all out of a desire to avoid being bored, or perhaps even that the solipsist is in fact living the most perfect life he or she could imagine. This issue is somewhat related to theodicy, the "problem of evil", except that the solipsist himself is the all-powerful God who has somehow allowed imperfection into his world. A solipsist may also counter that since he never made himself he never had a choice in the way his mind operates and appears to have only limited control over how his experiences evolve. He could also conclude that the world of his own mind's creation is the exact total of all his desires, conscious and otherwise and that each moment is always perfect in the sense that it would not be other than his own mind in total had made.

Solipsism undercuts morality-
If solipsism is true, then practically all standards for moral behavior would seem to be meaningless, according to this argument. There is no God, so that basis for morality is gone, but even secular humanism becomes meaningless since there are no such things as other humans. Everything and everyone else is just a figment of imagination, so there's no particular reason not to make these figments disappear by, say, mass annihilation. The subconscious mind could always imagine them back to life, if that's what's really wanted, anyway. The problem with this argument is that it falls prey to the Appeal to Consequences Fallacy; if solipsism is true, then it doesn't matter that it has unfortunate implications. This can possibly be countered by people who believe that (a non-solipsist) morality is an inherent part of the universe that can be proved to exist. A solipsist may also understand that everything being a part of himself would also mean that harming anything would be harming himself with associated negative consequences such as pain. Or a solipsist might say that harming others is imprudent because the solipsist can only be uncertain of their real existence.
The practical solipsist needs a language to formulate his or her thoughts about solipsism
Language is an essential tool to communicate with other minds. Why does a solipsist universe need a language? Indeed, one might even say, solipsism is necessarily incoherent, for to make an appeal to logical rules or empirical evidence the solipsist would implicitly have to affirm the very thing in which he or she purportedly refuses to believe: the 'reality' of intersubjectively valid criteria, and/or of a public, extra-mental world.A possible response would be that to keep from becoming bored, perhaps the solipsist imagines "other" minds, which would actually be only elements of his own mind. He or she has chosen to forget control of these minds for the time being, and the elaborate languages required for interaction with these more isolated segments of his mind are merely part of the creation of "reality." As for the rules of logic, they are probably merely an artefact of the peculiar psychology of the solipsist and only appear to exist in the "real" world. Greg Egan addressed this issue in his story "Dust" and the subsequent novel based on the story Permutation City by demonstrating that the solipsist can choose to develop his own self-consistent logical system apart from "reality". A more telling question might be, why does the solipsist need to invent so many and such a variety of languages? There is of course E-prime which strives to speak from the personal point of view and seems ideally suited for solipsism.

Realism vs. solipsism-
An objection, raised by David Deutsch, among others, is that since the solipsist has no control over the "universe" he is creating for himself, there must be some unconscious part of his mind creating it. If the solipsist makes his unconscious mind the object of scientific study (e.g., by conducting experiments), he will find that it behaves with the same complexity as the universe offered by realism; therefore, the distinction between realism and solipsism collapses. What realism calls "the universe", solipsism calls "one's unconscious mind." But these are just different names for the same thing. Both are massively complex processes other than the solipsist's conscious mind, and the cause of all the solipsist's experiences; possibly merely a labelling distinction. Application of Occam's Razor might then suggest that postulating the existence of 'reality' may be a simpler solution than a massive unconscious mind. The solipsist would claim that the apparent independence of real world events just shows how good his unconscious mind is at maintaining the illusion. The realist's world may be every bit as complex as the solipsist's unconscious, but when the solipsist dies, the entire universe will cease to exist. (See also, Le Guin, Ursula K. Lathe of Heaven Eos; Reprint edition (April 1, 1997))

Philosophical poverty-
Some philosophers hold the viewpoint that solipsism is entirely empty and without content. Like a 'faith' argument, it seems sterile, i.e., allows no further argument, nor can it be falsified. The world remains absolutely the same— so where could a solipsist go from there? Viewed in this way, solipsism seems only to have found a facile way to avoid the more difficult task of a critical analysis of what is 'real' and what isn't, and what 'reality' means. Some might say Solipsism is not impoverished because it helps philosophers operate from a principle of doubt because their difficult task can only determine the probability of what is real and what isn't. The solipsist would hold that further argument is meaningless and there are limits to what can be known about 'reality.' ..