Teaching English 109, I’m often struck by the fact that talking is easy, but writing is hard.* Why is that?
Here is linguist Jim Miller on the subject:
Many kinds of spoken language … have a syntax that is very different from the syntax of formal writing….[T]he differences exist not because spoken language is a degradation of written language but because any written language, whether English or Chinese, results from centuries of development and elaboration by a small number of users – clerics, administrators, lawyers and literary people. The process involves the development of complex syntactic constructions and complex vocabulary.
The syntax of spontaneous spoken language has been ‘designed’ or ‘developed’ to suit the conditions of speech – little planning time, the possibility of transmitting information by loudness, pitch and general voice quality, and support from hand gestures, facial expressions and so on (what is known as ‘non-verbal communication’). …[T]he syntax of spontaneous speech overlaps with the syntax of formal writing; there is a common core of constructions. For instance, “The instructions are useless” could be spoken or written. However, many constructions occur in speech but not in writing, and vice versa. “She doesn’t say much – knows a lot though” is typical of speech, but typical of writing is “Although she does not say much, she knows a lot.”
The special syntax of spontaneous spoken language is not produced just by speakers with the minimum of formal education. One of the most detailed investigations of spoken syntax was carried out in Russia in the late 1960s and early 1970s. The speakers recorded on tape in all sorts of informal situations were doctors, lawyers and academics, but their speech turned out to be very different in syntax from written Russian. Moreover, their syntax had general properties which have turned up in bodies of spontaneous spoken English, French and German.
People learn the syntax and vocabulary of formal writing from books and in school in a process that lasts into the early twenties for university graduates and can continue much longer. In general, the more exposure speakers have to formal schooling, the more easily and frequently they use in speech the syntax and vocabulary that are typical of formal writing.
Miller, Jim. An Introduction to English Syntax. Edinburgh: Edinburgh University Press, 2002. xii-xiv. Print.
And see: a transcript of a conversation.
*Obviously, talking isn’t easy for everyone. People with autism have trouble talking; people who’ve had strokes may have trouble speaking; etc. And talking in a foreign language takes years of practice to do well.