The point here is that the idea of a private language, like private colors and most of the other solipsistic conceits which this writer has at various times been afflicted, is both deluded and demonstrably false.

In the case of private language, the delusion is usually based on the belief that a word like “pain” or “tree” has the meaning it does because it is somehow “connected” to a feeling in my knee or a picture of a tree in my head. But as Wittgenstein proved in his “Philosophical Investigations” in the 1950s, words actually have the meaning they do because of certain rules and verification tests that are imposed on us from outside our own subjectivities, viz., by the community in which we have to get along and communicate with other people. Wittgenstein’s argument centers on the fact that a word like “tree” means what it does for me because of the way the community I’m part of has tacitly agree to use “tree.” What makes this observation so powerful is that Wittgenstein can prove that it holds true even if I am an angst-ridden adolescent pot-smoker who believes there’s no way I can verify that what I mean by “tree” is what anybody else means by “tree.”

Wittgenstein’s argument is very technical, but it goes something like:

(1) A word has no meaning apart from how it is actually used, and even if

(2) The question of whether my use agrees with others has been given up as a bad job, still,

(3) The only way a word can be used meaningfully even to myself is if I use it “correctly,” with

(4) “Correctly” here meaning “consistently with my own definitions” (that is, if I use “tree” one time to mean a tress and then the next time turn around and use “tree” to mean a golf ball and then the next time willy-nilly use “tree” to mean a certain brand of high-cal corporate cookies, etc., then even in my own little solipsistic universe, “tree” has ceased really to “mean” anything at all), but

(5) The criterion of consistency-with-my-own-definition is satisfiable only if there exist certain rules that are independent of any one individual language-user (viz., in this case, me). Without the existence of these external rules, there is no difference between the statement “I am in fact using ‘tree’ consistently with my own definition” and the statement “I happen to be under the impression that I am using ‘tree’ consistently with my own definition.

Wittgenstein’s basic way of putting it is:

>> Now how is it to be decided whether I have used the [privately defined] word consistently? What will be the difference between my having used it consistently and its *seeming* to me to that I have? Or has this distinction vanished? . . . If the distinction between ‘correct’ and ‘seems correct’ has disappeared, then so has the concept ‘correct.’ It follows that the ‘rules’ of my private language are only *impressions* of rules. My impression that I follow a rule does not confirm that I follow the rule, unless there can be something that will prove my impression correct. ‘And that something cannot be another impression — for this would be as if someone were to buy several copies of the morning paper to assure himself that what [the newspaper] said was true.’ <<

Step (5) is the real kicker. Step (5) is what shows that even if the involuted adolescent decides that he has his own special private definition of “tree,” he himself cannot make up the “rules of consistency” via which he confirms that he’s using “tree” the way he privately defined it — i.e., “The proof that I am following a rule must appeal to something *independent* of my impression that I am.”

[I]f you grant that meaning is use and language is public and communication impossible without consensus and rules, then without them, language itself becomes impossible. There must be *some* rules and conventions. We have to agree that “tree” has two of the letter “e” and lacks a “u” and denotes a large woody thing with branches and not a small plastic thing with dimples and TITLEIST on it, right?

(http://www.autoadmit.com/thread.php?thread_id=3255169&forum_id=2Firm#30705997)

I'm not convinced that language is consistent. It seems to me that (social) Language is just the overlapping consensus of (private) languages

(http://www.autoadmit.com/thread.php?thread_id=3255169&forum_id=2Firm#30706087)