My mother language does not have articles, so I still struggle to choose when to use the indefinte and definite article. The other day, I learned:

  • "The dog is an animal" is acceptable.
  • "The iron is a metal" is not acceptable. (By the iron, I mean the metal, not the device.)

Is that true? If so, could anyone explain why?

  • Try “Dogs are animals, but iron is metal.” No articles needed, although you may use a metal if you would like.
    – tchrist
    Dec 10, 2012 at 1:17

2 Answers 2


Yes, the pattern that you mention is true. The reason for the difference is that "iron" is considered to be a so-called mass noun, or "uncountable".

When you say something like "The dog is an animal" or "The corkscrew is a useful invention" etc, what you are basically saying is "Any prototypical example of a dog/corkscrew is...". In other words, for the sentence to work, you have to be able to conceptualise a "single example instance" of the thing/animal etc in question. For nouns that represent non-specific quantities of things, the construction isn't possible.

(For what it's worth, this actually differs from the 'generic' use of the definite article in various other languages such as French.)

So, compare the difference between:

(a) *The sugar makes any coffee taste sweeter. [When "sugar" is meant to mean "sugar in general".]

(b) The sugar cube makes any coffee taste sweeter.

(a) *The milk is a nutritious drink.

(b) The typical glass of milk contains 200 calories.

Note that sometimes, words like "sugar", "milk" and "iron" can actually be used countably in cases where the context makes it clear that e.g. by "two sugars" you mean "two teaspoons or sugar" and by "two irons" you mean "two atoms of iron". But despite this, such nouns aren't "countable enough by default" for "the sugar", "the milk", "the iron" etc to work as meaning "any prototypical example of sugar/milk/iron", and so sentences such as those above don't work.

  • I see. I was wondering why in French it's "L'eau est..." but in English it's "water is..." when referring to general water. So there was a difference between the definite articles of English and French.
    – Sindry
    Dec 10, 2012 at 0:25
  • 1
    Yes, the French case is different. In French-- and indeed many other languages-- the definite article can be used to form a generic construction with a much wider range of nouns. Dec 10, 2012 at 0:29
  • As I said, my mother language is Japanese which doesn't have artciles, so I couldn't understand why "the" can make the noun refer to both specific nouns and generic nouns. I arbitrarily assumed that "the" makes the noun work like an abstract noun or something. Your comment saying "Any prototypical example of a dog/corkscrew is..." is really helpful to me.
    – Sindry
    Dec 10, 2012 at 0:31
  • In that case, wouldn't it be possible to say "The iron is metal."? If "The dog" means all dogs, then why can't we say "the iron is metal"? We certainly can say "all iron". The explanation using prototypes makes sense to me. Or do you mean that "all irons" is unnaceptable and that's why "the iron is metal" is also unacceptable?
    – Sindry
    Dec 10, 2012 at 1:02
  • @Sindry Because a dog is quite demonstrably a count noun, whereas iron is not.
    – tchrist
    Dec 10, 2012 at 1:18

The dog in this sentence is a Definite generic noun phrase. It has specific syntax and usage.

As for the iron, definite articles have different senses with mass nouns, and these distinctions, like many others, are only prominent with count nouns.

As it happens, I wrote my dissertation 40 years ago on the subject of generic noun and verb phrases. Chapter IV is about Noun Phrases. But the most useful information is in the first link, on the three types of generic noun phrases.

  • 1
    Amazing! The first link provides exactly what I wanted to know. I'll try reading the dissertation as well later. Is "the piano" in "I can play the piano." a definite generic noun, too?
    – Sindry
    Dec 10, 2012 at 8:35
  • 1
    It doesn't matter there. In that sentence the whole verb phrase is generic, and the noun gets it from that. See Chapter II. (Note, by the way, that this kind of generic VP doesn't need can; I play the piano has exactly the same generic meaning as I can play the piano, although the former can also be used as an occupational generic -- see chapter III) Dec 10, 2012 at 14:37
  • 1
    I think now I understand the line "It's not that the articles the or a have special meaning..." you stated in the link. The meaning of the article itself is consistent in any case but the context changes its interpretation. So, my question now is, how can the meaning of "the" be consistent when it doesn't identify the noun at all in generic sentences like "the dog is animal." but it's supposed to be used to identify the noun? Well, I might as well post it as a new question.
    – Sindry
    Dec 10, 2012 at 15:44
  • Because articles don't have any meaning. They're just markers, auxiliary particles, crutches and flags to signal the structure of the constituent they're in. They're part of grammar, which is why you can't look them up in a dictionary and get any help. Dictionaries are for words that have meanings; grammars are for grammar. Dec 10, 2012 at 16:32
  • By the way, would you mind explaining me in detail about the "prominent feature" only with count nouns? I don't understand why we cannot refer to the prototypes of mass nouns using "the". Take "water" for example, we can still think of "what kind of matter water is" and "how does it feel when we touch it"...etc.
    – Sindry
    Dec 23, 2012 at 11:33

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