The character in Chinese texts brought to Japan through Korea at the beginning of the 4th century gradually came to be adopted by the Japanese for the writing of their own language, for which there was no native system of writing at the time.

Now, the Chinese characters were used phonetically to represent similar-sounding Japanese syllables--the meanings of the characters were more than often ignored. In this way, one could represent phonetically any Japanese word. But because each Chinese character only corresponds to one syllable, it was necessary to use many characters to write multisyllabic words, which frequently involved a large number of brush strokes.

To simplify this bothersome process, instead of the full angular style of writing (kaisho 楷書; box writing), a simplified derivative writing style was devised (sousho 草書; cursive writing). It came to be believed that the sousho style suited the Japanese litterary notation better.

Toward the end of the Nara period (710-794) and during the Heian period (794-1185) the sousho style underwent further simplification, in which esthetics played some part, resulting in a stock of phonetic characters extensive enough to represent the entire phonetics of the Japanese language. This was the decisive step towards the establishment of a purely phonetic character system representing syllables. These simple syllable characters are known today as hiragana, but were then formerly referred to as "onna-de" or ladies' hand because they were first used by women of the Heian period in letters and litterary writing, who were supposed to be ignorant of the exclusively male domain of Chinese learning, litterature, and writing. However, over time, hiragana came to prevail as the dominant syllabary.

Katakana was developped a little later, but not much. While listening to lectures on the classics of Buddhism, students wrote in their texts notations on the pronounciatation of meanings of unfamiliar characters, and sometimes wrote commentaries between the lines of certain passages. This practice required the use of some sort of phonetic shorthand, which led in turn to the development of katakana.

Like hiragana, katakana is based on Chinese characters corresponding to particular syllables. However, unlike hiragana, which is a cursive simplification of kanji, the more angular katakana were developped taking only single components of kanjis of the kaisho style.

Because katakana was closely associated with science and learning, this syllabary was for a long time exclusively used by men.

The selection of hiragana and katakana in use today was laid down in 1900 in a decree for elementary schools. Some obsolete symbols such as we ゑ,　ヱ, and wi ゐ, ヰ were dropped during reforms after WWII. As a result we have 46 kana recognized today.

Coming back to the topic at hand, one can easily notice nowadays that the purpose of katakanas has more than deviated from its origin. Most textbooks define its usage as needed for foreign words, loanwords, onomatopoeias even, yet they rarely state the important influence that it has over the evolution and modernization of the Japanese. Indeed, this syllabary holds many possibilities: authors and journalists alike tend to use it in order to fluidize their writing, something most of us are unfamiliar with, considering the difference in stucture between Japanese and most languages. Indeed, granted that it does not make use of spaces, reading it makes it difficult when only hiraganas are present, emphasizing the need for both katakanas and kanjis. Yet that is not all: any writer can choose katakanas because he simply forgot the appropriate kanji, or in other cases to underline or highlight a word, a meaning, an idea.

They can also participate in the process of language creativity and originality, where people like Haruki Murakami excel. Of course, multi-alphabetical languages are rare, which explains the trouble we may have in conceiving these principles. Furthermore, even the textbooks tend not to mention these aspects, remaining somewhat very relative and difficult to formalize.

But above all else, katakana is also the harbinger of what some locals call the "Westernization". Yet again, it would be quite delicate to rigorously define the effect that the rest of the world has on Japanese culture, but its presence is undeniable. After all, it manifests itself in the language, through katakanas. Words in katakanas are considered trendy. Companies that pick a word in katakanas are believed to be making the right choice (the common belief being that it shows you are opening yourself to the world). People start using foreign words in katakanas although there is a precise equivalent in strict Japanese. And as funny as it may seem, some foreign words have their meaning completely distorted in the translation process, for no apparent reasons: a バイキング (Viking) becomes an all-you-can-eat buffet, while a メタボ (Metabolic) girl should worry about her overweight. Explaining these alterations in language uses can be delicate, yet it might remain hard to argue the fact that it simply mirrors the occasional incomprehension that often arises when one culture aspires to understand another. Indeed, a language is one form of meme, it contains and by the same token is interpreted using all the cultural aspects it was born into, thus trying to transfer its essence into another language can lead to such results. As Stendhal said, "Le premier instrument du génie d'un peuple, c'est sa langue." (The first genius tool of a populace is its language).
In a sense, this state of affairs can be regarded as a new path for the development of Japanese, born from globalization, yet it is seen by many as  form of intertia, preventing the language from evolving the way it has been throughout its history. On this peculiar matter, allow me to tell you of a little story, in order to make things slightly clearer...

When Ayako Komata, 18, talks fashion with her friends, she throws around terms like ''hippu hangu'' [ヒップハング], or hip-hugging, jeans and ''shadoh'' [シャドー] (eye shadow), and ponders their effect on ''chou naisu gai'' [チョーナイスガイ] (very nice-looking guys).

This contemporary Japanese, spoken at breakneck pace and filled with English-sounding words, is incomprehensible to her grandparents. So when they complain that her underpants are showing, Ayako patiently explains that the fashion these days is to wear jeans just above the pelvis, which someone decided should be called ''hippu hangu.''

The Japanese government, like many older Japanese citizens, is unimpressed by these linguistic imports that are transforming the language. Invoking a widening communication gap in three-generation households, among other reasons, it has decided to act.

In an effort reminiscent of France's doomed bid to halt the proliferation of English words in the language of Molière, the government of Prime Minister Junichiro Koizumi appointed a panel to propose measures to stem the foreign word corruption in the language of Lady Murasaki, author of the 11th-century ''Tale of Genji.''

Their target is words written in katakana, a script largely reserved for writing the exploding number of trendy words imported from Western languages, especially English -- even though Japanese has been borrowing Western words, changing their pronunciation and giving them a Japanese flavor, at least since the 19th century. Before that it did the same thing on an even larger scale with Chinese words.

With his permed mane, snappy dress and plain speech, Mr. Koizumi himself has been a distinct trend setter. But the politician, who studied at the London School of Economics in his youth, has drawn a line when it comes to the purity of the Japanese language. He was moved to action not by the puzzling speech of teenagers, but by the English-infused and equally difficult-to-track bureaucrat-speak that surrounds him -- involving clunky Japanese derivations of things like outsourcing, back office, redundancy and accountability.

''How can ordinary people understand if I don't understand?'' the prime minister complained during a recent strategy session on how to revive Japan's technology sector.

Among the offending words was incubator, rendered ''inkyubeetaa'' [インキュベーター] when pronounced according to the katakana spelling. ''You have got to use expressions that are more easily understood,'' Mr. Koizumi said.

No firm regulations have yet been introduced, but the Council on the Japanese Language, a body somewhat akin to the Académie Française, is already honing its powers of persuasion. It says it will analyze newly arrived vocabulary each year and advise the government and the media to avoid terms it regards as unwanted or as confusing intruders.

''We do not think that katakana words will disappear from the Japanese language, because there are just too many arriving all the time,'' said Satoshi Yamaguchi, director of the Japanese language division of Japan's Cultural Agency.

He continued, ''The problem is there are so many words that most people don't understand.''

Among the recent offenders he cited were negotiation (negoshieishon) [ネゴシエーション], literacy (riterashii) [リテラシー] and interactive (interakutibu) [インテラクチブ]. New terms that mysteriously cleared the comprehension barrier, as measured by the language agency, included home helper (herupaa) [ヘルパー] and treatment (toriitomento) [トリーメント].

Some language experts think Mr. Koizumi is treading much too lightly. Rather than seeing the growth of English-derived terms as an inevitable side effect of globalization, which is striking cultures around the world, they see the spread of katakana words here as a uniquely Japanese peril.

''We Japanese have an inferiority complex over language which has turned into a dangerous longing,'' said Chikara Kato, a professor of linguistics at Sugiyama Jogakuin University in Nagoya. ''As a result, Japanese youngsters are taking a distance from Japanese and favoring katakana words. If you go into a clothing store that caters to young people, you'll find that everything is in English.''

In fact, although borrowings from English are by far the most numerous, they are not alone in invading the Japanese language. Many medical terms come from German, and in conformity with national stereotypes, the language of romance has been invaded by French.

A young woman who sleeps out for a night, unannounced to her parents, is said to have pulled a ''puchi iede'' [プチイエデ], or roughly a petit, or little, night out -- ''iede'' is standard Japanese.

People like Professor Kato become incensed over the thought that entire sentences can be strung together in contemporary Japanese using nothing but Western-derived words, save for an occasional Japanese verb or particle.

Try for example: ''Kasuaru use of katakana is not reezonaburu'' [カズアル／レエゾナブル]. Reasonable or not, the casual use of katakana seems almost uncontrollable, and most Japanese people, especially those under 50, seem unconcerned about the debate. The love affair with English is so well established here that a Japanese purification program would have to erase everything from the name of the country's perennial baseball favorites, the Yomiuri Giants, to renaming virtually every part in their automobiles, from the doa and taiya to the mootaa [ドアー／タイヤー／モーター] (door, tire and motor).

For his part, in fact, Tomatsu Komata, the 79-year-old grandfather of Ayako, affects nonchalance about the subject, claiming to have no difficulty understanding.

At 43, Sumiko Komata, right in the middle of this yawning language divide, knows better, and slyly begins to pepper her speech with borrowed terms like dilemma, policy and mental. A few moments later she asks granddad if he understands, and he throws up his hands in surrender.

''To tell you the truth, if we go to a restaurant and I don't understand what's on the menu, I just give it to her,'' Mr. Komata said, chuckling as he gestured toward his daughter-in-law. ''With all the new words, half the time I have no idea what they are serving.''

In its ambivalent state, the katakana syllabary is some kind of microcosm of the place that Japan has in the world chessboard. It holds many possibilities, and will definitely shape the language as time goes on. Now is the time to observe how the Japanese people will perceive and accept that change...

Sources:

Japan Times Online Version, Roger Pulvers, 07/22/2008
Japan Times Online Version, Thomas Dillon, 07/21/2010

New York Times - Tokyo Journal, Howard W. French, 10/23/2002

Mainichi Shimbun (Japanese Version)
Katakana & English - http://www.julieinjapan.com/
Strange Katakana Words - http://www.tofugu.com/2009/06/25/strange-katakana-words/