Which of the World's Languages is Most Difficult?

One thing that should puzzle and repulse thinking foreign visitors to Japan is the widespread insistence that Japanese is objectively one of if not the most difficult language in the world.  It's an insistence that is flatly unfalsifyable, and it's obviously insulting to the foreigner to whom it is directed!  

This is something I heard a lot when I first came here and started learning Japanese, and it is something I've heard a lot recently in the context of my first daughter, who is quickly developing proficiency with both English and Japanese.  Friends, relatives, students, clients, everyone wants to know every last detail about my daughter's linguistic development, and I suspect - at least for some - that this curiosity stems not from any altruistic concern for my daughter nor out of simple intellectual curiosity, but from the conscious or subconscious desire to get definitive proof from something as controlled as a bilingual child's development, that despite losing the war, despite being bombed and bombarded and used as a test case for the most destructive weapon ever produced and despite being occupied and neutered and told what to do and despite watching as cultural elements deemed too nationalist or obtrusive were gutted and dissected by occupying foreign authorities and despite having to reinvent culture as a strange blase neon avant-garde, there is still in Japan a deep-seeded and irrepressible drive to be Number One.

There is no number one.  There is no most difficult language.  Language is simply a tool for communication.  It's what you say - not the fine-detailed peculiarities of generative grammar or sound wave patterns - that counts.  Trying to objectively compare English and Japanese is like trying to decide whether a hammer or screwdriver is superior.

Learning a foreign language is a struggle to habituate to an entirely different and emergent set of conventions.  As a native speaker of English, I never had to sit down and memorize lists of Latin words (although the grammar was challenging at first), because the vast majority of them had found their way into English centuries before, and I already knew them.  Despite having never studied Spanish or Italian, my familiarity with the conventions of Latin means that I can read and understand a great deal of the works of Jorge Luis Borges or Dante Alighieri in their original languages without making much of an effort.  A native speaker of Mandarin Chinese can learn Wu or Cantonese in a similar fashion.  Many people from Luxembourg or Switzerland can speak five or more languages fluently, although there may be little actual variance among these languages.  

There is nothing like this for Japanese, which is heavily standardized and one of only two members of its Japonic language family.  (The other is Ryukyuan, or native Okinawan, which is very unprestigious.)  So if Japanese appears to require many hours of study for mastery, this is because the conventions of its vocabulary, grammar, syntax, idiom, and style are all completely unrelated to those of any other language family and must be learned from scratch.

Further complicating things is the writing system of Japanese.  For Indo-European languages, pictorial writing was developed, then syllabaries, then alphabets.  That is, the written forms of Indo-European languages started as representative of ideas and gradually came to represent increasingly basic phonemes.  

For Japanese, the sheer number of homonyms has made any sort of Japanese alphabet impractical.  And so, written Japanese consists of about 3,000 regularly-used kanji (Chinese pictorial characters) which have different readings depending on a wide variety of circumstances that native speakers of Japanese continue to learn through life.  This is punctuated by use of the Japanese hiragana syllabary - for grammatical points and some regular words depending on the targeted audience and the intended difficulty of the text - as well as the Japanese katakana syllabary, which is used largely for words borrowed from languages other than Chinese and for onomatopoeia.  The complexity of the Japanese writing system makes learning the written language a formidable task, and one with which even native speakers struggle for their entire lives.

The objective complexity of the Japanese writing system beside the point, an otherwise identical English sentence and a corresponding Japanese sentence encode the same information.  As does the corresponding sentence in Inuit or Swahili.  All that changes is what happens to all those bosons and fermions between your mouth and my ear.