The role language plays in shaping human knowledge (and consciousness as a whole) forms much of the Postmodern attitudes toward knowledge and our ability -- or inability -- as humans to accurately understand things (including ourselves) objectively.  Following is an outline of the basic linguistic premises and arguments guiding much Postmodern theory.

The Argument:

Premise 1: Humans think in language.  Yes, you are able to think of images and sounds, but the realm of concepts (thoughts about complex ideas like love, or God, or justice, morality, government etc.) exists in the realm of words, language.  If I ask you "what is love?" you must formulate and express your answer in words -- you might get a "feeling", but the idea will be formed in words.

Premise 2: Unlike math, human language is inherently "messy"; it relies on arbitrary, flexible, inaccurate and constantly changing relationships between signifiers (signs, words etc) and the signified (the idea, thing itself etc. being represented by the words).  For example, in contrast to the simple, mathematical argument 2 + 2 = 4, the single, simple word "love" has an infinite number of meanings not only across different historical times and cultures, but even among individuals within the same time and culture. 

Another example would be the simple dictate "Thou shalt not kill."  Even within a single faith tradition (Christianity, for example), believers cannot agree to the actual meaning of these four words.  Even if the phrase is boiled down to the oldest existing recorded version, scholars argue whether the text should read "No Kill" or "No Murder."  Beyond this, as it is clear the source (Old Testament) condones certain types of killing (acts of war, as a penalty to adultery etc.), it is difficult to determine what justifies "killing"; that is, even among believers, there is no agreement concerning the meaning.

It is this inherent ambiguity built into all languages -- and thus human consciousness -- that drives much Post Modern theory.

Case in Point: Who's On First?

Premise 3: Language is culture; all signs, sounds, words etc. are never purely objective: Different groups (cultures, academic disciplines, countries, generations etc.) use different words to signify different things; thus, all language itself is "contaminated" by (influenced by, defined by) the entirety of a culture's collective values: recall our lecture on all the cultural baggage carried by the simple words White/Black and how they relate to Ideology; you may not be a racist, but your culture's language retains inherently racist elements, and you are forced to not only communicate but think using this racially charged system of symbols.

To return to our example of "love", your definition of the word was shaped by your culture; what you think love actually is cannot exist in a vacuum separate from the love songs, romantic films, religious sermons etc. that you have heard concerning the nature of the concept "love".  Again, you may have innate love emotions, but the meaning that you make of those feelings cannot exist separate from your cultural influences (or "Ideologies").

To return to our example "Thou shalt not kill": we find that different cultures define justified killing vs. murder quite differently.  Modern Catholics consider the death penalty murder, while most American Protestants do not, and, of course, traditionally the Catholic Church condoned the death penalty for a wide array of crimes that most Americans would not (i.e. heresy).

Thus, Post Modern theory argues, the very definition of a simple term like "to kill" or "to murder" never refers to a single concept; all concepts are rooted in cultural Ideology, and cultural Ideology is "tainted" by relations of power and bias -- that is, it is never as objective as it first appears and, indeed, is incapable of representing reality objectively.

Conclusion: This inherent, inescapable, nature of human thought and language (that thought is language and language is faulty) makes it impossible for humans to accurately grasp the nature of reality, or, more to the point, for any speaker to escape his or her own cultural Ideology: language itself, forces all thinking to remain Ideological.

This is complicated by the observation that all knowledge is existential; in the most stark terms, there are "no innate ideas" (ah, that idea that just keeps on giving). For this reason, we can observe that different cultures (using different languages or "systems of thinking and communicating truths") evolve different "knowledges" or beliefs.

Radical Post Modern theory, then, attacks Enlightenment Rationality (that is, "science"), as just another Ideology, and therefore no more objectively true than any given religion.

Basically, at this point Locke's no innate ideas has finally collapsed in on itself.Implications of PoMo Theory