Why you shouldn’t rely on grammar rules

by Tomasz P. Szynalski

Here is an excerpt from an ESL textbook (Workout Advanced by Paul Radley and Kathy Burke, published by Nelson English Language Teaching). The textbook was used in an English class I attended at a language school in England.

Unit 4. Grammar: Adjectives
When two or more adjectives are used before a noun, the adjectives follow a certain order:
opinion adjectives: general/specific
descriptive adjectives: size/age/shape/colour/nationality/material
Example: They bought a lovely, stylish, large, old, rectangular, brown, English oak table.

— next page —

Use the adjectives in the correct order before each noun to make noun phrases.
Example:
beach — white, sandy, soft → a soft, white, sandy beach
hotel — modern, large, expensive
climate — sunny, warm, Mediterranean
water — blue, clear, clean
restaurant — international, open-air, clean
rooms — spacious, comfortable, twin-bedded

The textbook presents a grammar rule for ordering adjectives: “size–age–shape–color–nationality–material”. Then it gives only two examples. Then you are expected to do an exercise.

Obviously, you’re not supposed to do the exercise using your intuition (what intuition can you get from seeing only two examples?). The textbook wants you to use the grammar rule.

More examples of grammar rules

we do not use must to talk about external obligations (~~I must come to work on Saturdays~~)
we form questions with modal verbs (can, could, would, etc.) by putting the modal verb first, e.g. Can you cook?
lexical verbs, but not modal verbs, need an -s suffix in the third person singular (She sells oysters, but not ~~She cans sing~~)
we do not use the present perfect tense when we’re thinking about a finished period (~~I’ve finished the project last week~~)
we use when, not while or as, to talk about life periods (When I was in school, my sister was already married)
when a verb ends in a single consonant in a stressed syllable, the consonant is doubled in -ed and -ing forms – e.g. wrap → wrapped, admit → admitted, but visit → visited
in a since-clause that refers to a point in time, we use a past tense (He’s been lording it over me since he got promoted)
when describing a number or quantity, we usually prefer under, but when we’re thinking about a vertical scale, dropping or falling, we usually prefer below (under 10 seconds, under 18 years of age but the stock dropped below 20 dollars)

Time

What exactly are you supposed to do in this exercise?

Recall the rule (“opinion adjectives go first, then descriptive adjectives in the order: size–age–shape–color–nationality–material”).
Take a look at each adjective and put it in the right category (“Is it an opinion adjective or descriptive adjective? If the latter, does it describe size, age, shape, color, nationality, or material?”).
Order the adjectives according to the rule.

This is fine if you just want to complete the exercise, but what about using English in real life? Imagine going through the mental process of categorizing and ordering words every time you want to write or say a sentence with two or more adjectives.

The above rule is admittedly quite complicated, so in the interest of fairness let’s have a look at a simpler one:

When talking about something that was in progress at some defined point in the past, we use the past progressive tense (e.g. I was taking a shower when the telephone rang; What were you doing at 8 pm yesterday?)

Here’s what you have to do in order to use this rule:

Recall the rule.
Check if the sentence defines a point in time – for example, in I (do) my taxes yesterday, the rule does not apply because, although doing taxes takes time and so must have been in progress at some point, that point is not defined in the sentence.
Check if the action was in progress at that point – for example, in My parents (freak out) when I told them I was pregnant, the rule does not apply because the action started after the point in time specified by the when-clause.

Although this rule is more usable than the adjective order rule, you still have to do some mental gymnastics before you can apply it.

Here’s the thinking behind grammar rules: Native speakers learn to use the past progressive tense the way they learn all of grammar, by absorbing a massive number of example sentences. But native-like, intuitive knowledge builds up slowly. That’s not good enough if you’re a teacher and you want your students to show clear signs of progress on the next test. So you take a shortcut – you tell your students to memorize one rule that captures the essence of all these examples.

Because rules are generalizations based on many example sentences, they are always phrased in terms of categories like “opinion adjective” or “defined point in time”, which represent many different phrases (stupid, disgusting, funny, at 10 am, 30 seconds ago, when I came home from work, etc.). This means that, in order to apply them, you first have to check if the relevant parts of your sentence belong to the appropriate category. This takes time and conscious effort.

Contrast this with input-based learning, where you absorb a large number of examples and your brain extracts associations from those examples (e.g. this verb goes with that noun, this verb form goes with this type of situation, etc.). At the end of this process, when you hear somebody say something like ~~No, I don’t want~~, you instantly get a little voice in your head that tells you “there’s something wrong with this sentence”. You don’t need to perform any rule-matching gymnastics.

Memory

It is a fundamental fact of neurology that if you want to keep something in memory, you have to review it. In input-based learning, reviewing happens all the time. With every sentence you read, you refresh the meanings of words, the meanings of grammar structures, the associations between words and grammar structures, etc. There is no such natural review mechanism for grammar rules.

Because of this, grammar rules tend to evaporate from memory rather easily. Often, they do not disappear completely, but become slowly deformed:

two things get mixed up, for example:
- “Was it below or under that’s used when talking about dropping or falling?”
- “Was it age–shape–color or shape–age–color?”
the rule gets “simplified”, for example:
- “When a verb ends in a single consonant, the consonant is doubled in -ed and -ing forms”*
- “We use the simple past in a since-clause”**

Coverage

It’s important to understand that grammar rules are a very different thing than rules governing a formal system like the game of chess or the Python programming language. In a formal system, there is some kind of central document (usually written by some authority) that lays down the rules, which are then followed by everybody who uses the system. If you want to play chess, for example, you have to learn and obey the rules for making legal chess moves. If the World Chess Federation decided tomorrow that pawns can no longer move by two squares in their first move, chess players all over the world would have to comply with the change.

*) apart from a handful of rules of “proper English” that teachers cram into students’ heads to make them unlearn the informal, spoken grammar that they learn in the real world in favor of “proper” written grammar (e.g. “don’t say less friends, say fewer friends”)
**) To be sure, their brains extract some patterns from the input and we could call such patterns “rules”, but they are not formal rules that you could put in a document, and they are fuzzy (for example, there is no sharp boundary between correct and incorrect sentences – native speakers might describe some sentences as “a bit weird”, “slightly off”, etc.)
†) There are “language experts” who have made entire careers out of telling native speakers how they should speak. They have very strong opinions about grammar and often write articles criticizing certain commonly used phrases and grammar structures, labeling them as “errors”. For example, they might insist that you should say it is I instead of it’s me, different from/to instead of different than, neither X nor Y is instead of neither X nor Y are. However, these people are not taken seriously among academic linguists, they seem to have little effect on the English language, and – most importantly – their opinions are limited to a small number of pet peeves and are nowhere near a comprehensive specification of English grammar.

Language is not a formal system. It is a spontaneous phenomenon that has evolved through everyday communication within groups of people. There is no English rule-book, written by the Central Committee of English, that decides what is a correct English sentence. When children learn English, they don’t learn any rules* – they simply listen to sentences spoken by their parents and other people around them.** When they grow up, they produce their own sentences, which serve as input for their children, and so on. Formal rules don’t come into play at any point in this chain.

There are, of course, linguists who write grammar rules like “adjectives of size come before adjectives of color”. But they are not the designers of English and do not have authority over how English is spoken. If all the grammar books in the world decided that, from now on, I need drink is a correct English sentence, nobody would care – communication would simply go on as before. Unlike chess rules, grammar rules don’t dictate how English should be spoken – they only try to describe how English is spoken.†

Where do grammar rules come from? Linguists analyze sentences produced by native speakers. If they notice some patterns, e.g. that native speakers almost never say things like ~~red big car~~, ~~white small house~~, etc., they try to describe these patterns in the form of rules, such as the size–color rule. Naturally, if the way people speak changes, linguists have to update their descriptions.

Grammar rules try to describe human linguistic behavior, but human behavior is complicated and difficult to describe in a formal way. For this reason, grammatical descriptions will never be able to capture all the complexity. There will always be nooks and crannies of grammar which are not described by grammar references.

One source of difficulties is that sometimes a sentence doesn’t follow the normal grammatical rules for sentences of its type. Grammar books will often list some of the most important exceptions for the most important rules, but they obviously don’t have enough space to include all the exceptions for all the rules. For example, you’re not likely to find the following facts in your grammar book:

Certain verb phrases like talk business or fly British Airways can only be used in the active voice. We can say Let’s talk/discuss business and Business shouldn’t be discussed at home but not ~~Business shouldn’t be talked at home~~.
Possessive ’s is often used with nouns which refer to people or groups of people (my sister’s room, the court’s decision, America’s future). It can also be used with certain other nouns (the earth’s surface, the show’s creators, the car’s engine), but not others (~~the hill’s top~~, ~~your voice’s tone~~, ~~the road’s side~~).

Sometimes the problem isn’t just a fixed number of exceptions, but a more general situation where it’s hard to identify the exact conditions that favor one structure over another:

Many verb phrases which refer to completed actions, such as read a book, can be combined with for X hours. This makes the action incomplete – for example, I read a book normally means that you finished reading it; I read a book for an hour suggests that you didn’t. However, some verb phrases seem to be incompatible with for X hours: ~~I wrote an article for an hour yesterday~~, ~~I built the shed for an hour yesterday~~.
A very large number of verbs (e.g. criticize, steal, organize, postpone) can be used without an object (intransitively) only in certain contexts. Which contexts? Unfortunately, that’s not easy to define. For example, we can say I don't want to criticize, but... and She criticizes too much, but not ~~When I told my parents about my plans, they criticized~~ or ~~She always criticizes~~.
Grammars say that the present perfect is used to talk about the present results of past actions. What they don’t explain is that this only goes for certain types of results. For example, I’ve decided to quit; I’ll talk to my boss tomorrow is correct, but ~~I no longer work there; I’ve decided to quit~~ is wrong (it should be I decided). Although both sentences are focused on the present results of the decision to quit, the second result is too distant to use the present perfect.

Are grammar rules useful in learning a language?

The first thing to understand about grammar rules is that you may not need them. Native speakers don’t know any rules; there are also many quite competent learners who have learned English without ever doing a grammar exercise.

We have seen that grammar rules don’t cover all the facts necessary to speak English fluently, but that’s not the biggest problem. More serious are the issues I’ve discussed in the Time section above: applying rules to your sentences slows you down so much that you cannot be truly fluent. Therefore, your ultimate goal as a learner should be to use English without relying on grammar rules too much. This does not mean you cannot use grammar rules as a temporary crutch in the process of reaching that goal. You can learn a rule for some grammatical structure, and if you keep applying it in your own sentences, or in grammar exercises, at some point you will probably find that you have internalized it – that is, you no longer have to think about the rule and are using the structure intuitively. Before that happens, however, you will have to suffer a reduction in fluency.

This brings us to the final – and most serious – problem with grammar rules. For internalization to take place, the grammar rules have to stay in your brain long enough. And, as discussed in the Memory section, grammar rules don’t stay in your head by themselves. Just using them when writing or speaking in English won’t cut it. Because the amount of time spent on producing output is relatively small*, you are likely to forget a rule before you have the next natural opportunity to use it. Grammar rules require dedicated reviews.

An obvious review strategy would be to create a large number (probably thousands) of SRS items with targeted grammar exercises, and then apply a grammar rule every time you have to answer an item. Another way would be to incorporate grammar rules into your reading in a kind of hard-core “pause and think”. Let’s say you’ve read the sentence They ran across the field. Rather than just noting that it says across and not through (as you would in normal pause and think), you would recall the whole rule: “we use across when we’re on some surface, and through if we’re surrounded on all sides”.

Stopping in order to recall a grammar rule is, of course, quite time-consuming, as is creating SRS items and reviewing them. However you choose to review grammar rules, it takes discipline and time. That is time that you could spend doing other things, like getting more input or playing badminton.

It’s always worth remembering the nicest thing about input – the fact that it’s essentially free. When you watch TV shows or read interesting sites on the Internet in English, you are doing something that you want to do anyway (getting knowledge or entertainment) – learning English is just a nice bonus. This is what makes input so efficient as a learning method (in addition to the fun and the motivation that it gives you). Therefore, if you can learn something from input, you should learn it from input.

In addition, as discussed above, grammar rules require artificial reviews – otherwise, you will just forget them soon after you learn them. But if you have a system for artificial reviews (like an SRS), you have better options at your disposal. When you find that some grammar structures are giving you problems, you can just use standard gap-filling items without thinking about grammar rules.* For example, you could add a question like: I haven’t had a good burrito since I ___ (move) to Europe. This technique will give your brain a chance to see hard-to-learn structures more frequently, which is what it needs to develop a natural, intuitive “feel” for them. If you have difficulty remembering the correct answer to a grammar gap-filling item, you don’t have to learn a grammar rule – you can try to memorize the correct phrase instead (e.g. since I moved to Europe). Memorizing an example is often easier than memorizing a grammar rule. It is also much closer to natural, input-based learning, so it’s probably more likely to result in native-like, intuitive knowledge.

Grammar rules as a last resort

So if you’re going to use grammar rules, the smart strategy is to use them only when you have to.† In short:

Learn what you can from input.
If you notice some things are hard to learn, don’t go straight to grammar rules. Instead, fire up your SRS and add some gap-filling or sentence items targeting the structures that are giving you problems.†† Don’t worry about grammar rules at this point – the idea is to try to build intuitive, input-based knowledge, which is the best kind of knowledge.
If you have difficulty remembering the correct answers to some of your grammar SRS items, go ahead and read some grammar rules. You could add them as notes to the answers in your items (e.g. “don’t use must to talk about external obligations”).

By the way, there is nothing unusual about needing to do extra work on some parts of English. Input always leaves some gaps in your knowledge because some words and grammar structures just don’t occur in natural input frequently enough to produce strong memories. The important thing is to be careful and check your own writing so that you are aware of these gaps and can take action to fill them. If you’re not aware of them, you’re in danger, because you may fill them with your own dialect of English, as less successful learners often do.

Are there any other good ways to use grammar rules? I can think of one: If you’re a beginner learning a new language, it can be a good idea to get an introduction to the basic grammar of that language – how you form questions and negatives, how you talk about the future and the past, how you inflect nouns, verbs and/or adjectives, which structures are the most problematic for learners, etc. It makes it easier to understand what you read, and helps you focus on grammar when you pause and think. “Getting an introduction” does not mean memorizing the rules – reading about them should do.

Other types of explicit learning

The weak points of grammar rules apply to all kinds of explicit learning (learning based on description rather than examples). Take definitions of words, e.g. acclaimed = publicly praised by a lot of people. They take a lot of time to use because you have to recall the definition and then decide whether it fits your sentence. They are hard to memorize. And they often don’t capture all the shades of meaning.

About asking ‘why’

When you tell an English learner the correct way to say something in English or you correct their mistake, you know what usually happens next? They’ll ask you “why?”.

Why can’t I say ~~red big car~~?

Why do you say that someone is under 18 but the temperature is below zero?

Why can’t I say If I ~~will~~ get this job, I will finally pay off my debts?

Do you do that, too? I think it’s problematic for two reasons:

It assumes that the person you’re talking to actually knows the correct grammar rule. But being a native speaker or an English teacher doesn’t mean you know anything about grammar. In reality, the only people who can give you reliable grammatical facts are people who are particularly interested in grammar. When you ask someone who’s not a grammar geek, the risk is that they will make up some bogus rule on the spot (e.g. ~~“we never use will after if”~~).
It assumes that learning a grammar rule is a good idea – that if you hear an answer like “we say big red car because adjectives of size come before adjectives of color”, it will somehow help you with adjective order in your own sentences. But for all the reasons discussed in this article it doesn’t work that way. If you don’t have a serious system for reviewing grammar rules (like an SRS), you will forget the rule in the blink of an eye. (And if you do have a review system, you usually won’t need grammar rules – you can just use the system to do regular gap-filling exercises.)

Instead of wondering “why?”, simply learn the correct way. Follow native speakers, not grammar rules.