One of the first things you realize when you study linguistics is that language, every language, is filled with an amazing amount of complexity and regularity to the point of defying description. And I mean that literally. There is not one single natural language that has been completely formalized at all levels of description in any way. So, with that said, the answer to the above question is pretty much all of the rules we don’t know but still follow. Well, we actually know them, but this knowledge can be described as tacit knowledge; stored under the threshold of consciousness. To put it in another way, we know these rules but we don’t know that we know them!
Think about this for a second.
Even English grammar, the ins and outs of which have been studied by thousands of people for centuries on end, has not been completely described. You can’t go anywhere and pick up a book or look up a computer program that has all the rules of English. Thus, there is no documented list of the rules an English speaker is supposed to know and so most native speakers don’t really “know” most of the rules of English.
So what are English teachers teaching you in school and what are William Strunk Jr. and E.B. White (Strunk & White, The Elements of Style) getting all in a huff about? And what are the grammar rules and language lessons that the state spends millions of dollars to teach us? Well, the rules people talk about—in blogs, in English classes, in ESL classes and so on —are:
1) Rules that are in the process of changing, e.g., How do I stop being annoyed by people using literally as an intensifier?
2) Rules that carry inordinate weight as social signals (e.g., gonna, or dangling participles: Where you at? or even Where are you from? instead of From where are you?)
3) Rules that are particularly confusing to newcomers (Adjective order for instance)
4) Rules that are cool and/or funny.
The fact of the matter is that almost everything we know about our native languages is what’s called implicit knowledge. Stuff we don’t know that we know, or stuff that we can’t really describe, but we can do anyway. Like maybe riding a bike, or walking. Indeed, we can go through all the levels of linguistic description: phonetics, phonology, morphophonology, morphosyntax, syntax, semantics, pragmatics and pick out some of the most basic rules and pinpoint discrepancies in explicit knowledge. Let’s see that together.
Phonetics:
How do you pronounce the letter p? Easy, right? Well, there are actually a number of different ways p is articulated in English. English speakers pronounce it differently without realizing that.
Compare, for example, ‘spot’ and ‘pot’. They sound the same to an English speaker but put your hand an inch from your mouth when you say the two words and you’ll notice a much bigger puff of air for the p in pot. You don’t feel that puff of air in spot do you? (I’m talking about native speakers here, it’s hard for a non-native to notice the difference if they hadn’t explicitly been taught this at a phonetics class).
Indeed, in many other languages, these two types of p, aspirated and unaspirated. are two completely different sounds. Languages such as Armenian, Korean, Lakota, Thai, Indo-Aryan languages, Dravidian languages, Icelandic, Ancient Greek, and some varieties of Chinese are all languages in which aspiration is phonemic. That is, aspirated and unaspirated consonants are two different phonemes; if you change one with the other you get two entirely different words. Returning to English, if you cut the s off the word spot you’re left with something that actually sounds like bot, not pot.
Native English speakers never make a mistake here, but don’t even know they’re doing this complicated articulatory gymnastics, saying p differently in different contexts; “it’s just p” we think.
The same holds for pretty much every phoneme (sounds letters) in something called Allophony: The phonemes t and k also adhere to this Aspiration rule; t is also involved in a flapping rule (the t in duty is d-like, which speakers may actually know because, well, doody!!!!!!!); l is different in the onset vs. coda of a syllable (look vs. cool) and so on and on and on.
Phonology:
What makes something sound like an English word? There are dozens, if not hundreds, of rules governing where sounds can go in a word, i.e. phonology, that most speakers are not aware of. If I ask you which word sounds more like a real word zbashk or sneeld , every native English speaker would answer the same way, Russian speakers would answer differently, but without much insight into why. (The reason I say this is not because it means native English speakers are ignorant, but even linguists haven’t figured out the precise details of how people make word-likeness judgments).
Morphophonology:
How does pronunciation change when you add affixes to a word? The stress in parent is syllable 1, add a suffix, -hood, and it’s still syllable 1, parenthood, but add –al and it shifts: parental. Why the difference?
Another one: you may know why some words are un- and other words are in- as in unable but incapable (hint: it’s primarily word origin). You might have even noticed that in– assimilates to the following sound (e.g., illegible, impossible, irregular). But why not umbelievable? Or ullimited?
The answer has to do with whether there are serial levels, or strata, of processing in morphophonology—a debate still raging today—with in– being in an earlier stratum (before consonant assimilation) and un– being in a later stratum. How do native speakers follow these rules without knowing them? We don’t know!
Morphosyntax:
When do you use accusative case pronouns? To provide an example of something that we think we know, but we actually don’t: When do we use the accusative form of pronouns in English (me, him, her, them)? When it’s the object of the sentence, Object Pronouns Grammar Rules, right? Well, not quite. Consider the following:
Q: Who wants cake?
A: Me
Me and John went to the store
She thinks I am smart.
She considers me to be smart.
She considers me smart.
The rules of case assignment just got real complicated. So real that linguists still aren’t quite sure how it works. How do you want a speaker to know a rule that even linguists haven’t figured out yet?
Syntax:
What is English word order? How about something as basic as can be: word order? English is subject-verb-object, right? Well, that rule I don’t like so much. (interjection, object, subject, verb, adverbial phrase). You get that?
Semantics:
How do you interpret words like some and every? Consider these two sentences:
There is someone who loves everyone.
Everyone is loved by someone.
The second sentence can mean what the first sentence means, but it can also mean that everyone has some person that loves them, but it can be all different somebodies.
Pragmatics:
Who gets talked about next in a discourse? Conversation is complicated. If you actually listen to recordings of your conversations it’s any wonder that anyone understood anything. One of the really hard parts is reference resolution. When you say he or she or her or his, who the heck are you talking about? Seth talked to his brother when he was sick. Now, who was sick, Seth or his bother?
Well, one “rule” is that certain verbs implicate certain arguments as the topic of conversation. So, in John annoyed Tom because he … you presume he refers to John whereas John admired Tom because he … means you’re more likely to then talk about Tom.
Without these little rules of conversation, we’d be lost when talking to each other. But they are rules that you aren’t generally taught and they are rules we generally aren’t aware of. And they are rules that we haven’t even pinned down particularly well. Reference resolution is one of the hard problems for natural language processing.
Indeed, if we knew the rules of English, it wouldn’t be so hard to program a computer to follow them. But we don’t, so we can’t.
So, in this small selection of rules, we have actually seen the most mundane things about just English: How do you pronounce p? What is English word order? When do you use accusative case? How do you figure out who pronouns refer to? How do you add suffixes to a word? Not the funniest or trickiest, but the ones that show that even the most fundamental aspects of grammar, the rules that allow us to communicate in even the most basic ways, fly below the radar of our awareness.
Any language is a supreme achievement of a uniquely human collective genius, as divine and endless a mystery as a living organism.
Steven Pinker.