The problem of human subjectivity has fascinated thinkers at least since the early Greek philosophers. Sophism was a movement which mostly rejected that there is a reality common to all humans because there are irreconcilable differences in individual persons perceptions (i.e. 'what is cold for you can be warm for me etc.). It was unable to explain how any communication between minds and hence agreement about the nature of many things could take place, which most apparently does occur. Most major European thinkers rejected this solipsism - at least since Socrates confronted it - with a few exceptions like Leibnitz, Bishop Berkeley and F.H. Bradley. As one succinct example of the key solipsistic idea, see F.H. Bradley (scan on right) The reasons for re-adopting solipsism - what all 'common sense' (!) rejects as an extremist position, was bolstered greatly by modern physics with its discoveries of the deeper nature of matter. The views of physicist David Bohm suggesting that no objective reality exists added stimulus to this solipsism. Add to this the globalized spread of many previously rather isolated religious scriptures and related doctrines which appeal to solipsism - also giving rise to so-called 'new religiosity or spirituality' (as in New Age doctrines) - and we have an increasing interest among the myriad of newly emerging and less philosophically broad or sophisticated Internet writers in theories which are basically solipsistic. There is also inherent solipsism in certain India theologically based theories of advaita (non-duality) as promulgated by numerous 'spiritual gurus' (I have analysed certain trends and shown their untenability elsewhere - see links at foot of this blog).
The general view expressed by Bradley can serve as the basic conception that most solipsists assume. In a nutshell, one may say... each person enclosed and cut off totally from others in a subjective 'world', an 'inner world'. Yet the fact that there exist "others that surround it" is noted, though no one who is locked into a private world can know that there really are 'others', that is, other persons who exist independently of one's own perceptions. Though common sense (sic) revolts against this view of life, it does have some genuine basis in what we experience and know to be the case, so to refute it definitively requires considerable dexterity. This solipsism is at the root of much religious thinking, especially esoteric and mystical doctrines of a kind leaning on Eastern religion such as most so-called New Age "philosophies" do. The idea that "reality" is all within oneself, that the soul is the seat of the divine inner unity which alone is real and eternal (as with 'the Christ within' or advaita vedanta and so on). I shall illustrate some critical approaches through analogies between persons and computers, though not, of course, so as try to prove one case from the other, as arguments from analogy are not sound logically.
On how communication between minds is possible: If it were so that every mind were a self-contained and isolated entity (in Leibnitz' famous phrase 'monads that have no windows') then the apparent phenomenon of mutual communication and agreements and disagreements between minds as to anything would have to be explained... in fact, no explanation that accounts for the facts has yet been achieved. According to the solipsistic assumption, all that we could perceive would only be a mirror image of out own thoughts and there would be no objective referent whatever. The cat is that communication does take place, and not only between human minds. This occurs without having to invoke ideas like telepathy or the like but through all the ordinary senses and not least instruments that extend their range (eg. the telephone). In an analogy, minds are connected to each other as computers are inter-connected through the internet. One cannot draw logically valid conclusions from analogies, but analogies can sometimes be not only illustrative by accurate in comparison. (Incidentally, the idea of mirroring has been used effectively by some gurus to control their followers by claiming that their perception of them as guru is all their own making, for the guru is omnipresent within their deepest inner reality!)
Comparing persons to computers, and applying the 'private world' assumption to the latter: one would one say that each separate computer terminal is in a similar situation... its 'contents' are uniquely its own. It's memory contains its own 'world'. This is reasonable enough, despite the fact that it also can share its contents with other computers. Yet here we begin to see the analogy indicating that the solipsist position is untenable... for computers DO share their contents - one can even share its entire contents with any other computer if required. It runs on hardware and software which it shares with all other computers that run on the same types. If a person's brain is regarded as the hardware, and the standard electro-chemical reactions as a kind of software, then one can argue that one healthy brain is sufficiently like any other to compare to computer systems. Who can deny that human brains do not share contents with other brains (or, if you prefer, with minds or with persons)? To deny it implies that everything, without exception, is an illusion of reality, other than the subjective 'illusion' itself.
To extend the analogy for the purpose of illustration, computers that access the Internet are able to partake in any part of the common data source on-line. Likewise, persons share in common culture - increasingly in the global culture made possible not least by the Internet. Though there are many and varied human cultures, with indefinite boundaries and many bleed-through features, there is a basic common culture too... one that is the lowest common denominator of what it is to be a person, to have human perceptions, senses, thoughts and feelings. To doubt the existence of such commonality is to show one had a very provincial and narrow experience of the world. As soon as a highly specific cultural phenomenon is made available to the most foreign culture - say by the translation to the foreign language, or by graphic or visual means - it is invariably understood and valued in similar ways. There are countless examples, from the spread of science throughout the world to the appreciation of the arts in cultures once entirely foreign... take as a concrete instances the Japanese embrace of the Sherlock Holmes novels of Conan Doyle, the Chinese assimilation of Western classical music.
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