Using “the” instead of “a” for something that isn't a specific object
Link to original question: Using “the” instead of “a” for something that isn't a specific object
It might be helpful to put the thought of "specific" or "nonspecific" object on hold just for moment. A broader category is "definite" and "indefinite". Which is why we have the definite article and the indefinite article. As we will see, both of these can be used to make a specific reference to an object.
In English, all singular count nouns (such as ones you have used either in your post or in comments: 'object', 'copy', 'controller', '(diesel) car', 'page', 'rule') generally require a determiner of some sort. The most common determiners are the indirect article (a/an) and the direct article (the). So we are obliged to make either a definite or indefinite reference.
The choice of making a definite or indefinite reference to a noun in not based on a rule, it is based on which kind of reference that the speaker (or writer) wishes to make. That is why any list of rules can only be guidelines. Such rules may be a help for language learners, but they can never adequately cover actual uses. Because actual uses are based on the speaker's intention: does the speaker want to make a definite or indefinite reference?
In general, the speaker makes a definite reference, when
1. He assumes or believes that his listener can uniquely identify the referent (the noun referred to), from
a) context
b) shared knowledge between the speaker and listener (the cafe we always go to)
c) knowledge about how things work (most houses have front doors, so: the front door of a house you have never seen before)
c) knowledge about the world (who won the fight tonight?)
Notice this is based on the speaker's assumption; this assumption does not have to be true.
2. At times, to introduce a new topic for discussion
Example 1: And that's when I saw the giant green peppermint in my driveway.
Example 2: Honey, I saw the cutest little dress on sale at Macy's.
3. Just to freak you out. I am serious. Language allows for a lot of creative play and/or ambiguity. So a speaker/writer can make a definite reference to an object even when he knows that you cannot uniquely identify the object. This is something you won't find on a list of rules!
Consider the following between two roommates. Jocko has not bought a new shirt in months; Tooly knows this, but is playing with Jocko:
Tooly: Wow, the new shirt you bought is tremendous.
Jocko: What new shirt?
Tooly: Psych! (Or: Gotcha!)
And the speaker can make an indefinite reference, when
1) he wishes to avoid making a definite reference (yes, dear, I saw a note on the fridge)
2) the speaker doesn't think it's important to make a definite reference (there's a book at home I want to read)
3) when the speaker does not believe that you can uniquely identify the referent (I need to order a new part for the dishwasher)
4) to introduce a new topic for discussion (The school sent a progress report about Jane today.)
5) at any other time that the speaker or writer wishes to make an indefinite rather than a definite reference, which can mean that none of the above apply.
So what's this 'specific' and 'nonspecific' reference? First a definite reference that is not generic is always a specific reference; while an indirect reference can be either a nonspecific or specific reference.
Thus
I want to buy a new car is a nonspecific reference if the speaker does not have a specific car in mind
whereas
I just bought a new car is a specific but indefinite reference, because the speaker is referring to a specific car.
Note: this post is talking about non-generic references. Generic references are a subject that requires a separate post. But they include references to a prototype of an object, such as The leopard's habitat ranges from Africa to Asia. Here the makes a definite, generic reference.
NOW:
This game requires the Classic Controller
The speaker/writer makes a definite reference. It is your job as a reader/listener to figure out why, if you can. Most the times it is obvious or automatic; the definite reference above can be made because the speaker assumes you can uniquely identify the referent (that is: know which controller he is talking about) from context, shared knowledge, knowledge about the world, knowledge about how things work. It has nothing to do with the Classic Controller being a proper noun.
But notice you also said that "This game requires a Classic Controller" seems to be correct as well. And it is. It is just that the speaker/writer made a definite rather than an indefinite reference because he wanted to.
Also note that something that is definite is usually perceived as something that is more clear or firm. When talking a product, a company is more likely going to speak about it in clear and firm terms. In other words, an indefinite reference can be seen as somewhat wishy-washy or imprecise. Not exactly the image a company wants its product to have!
as we don't say "this pump is for the diesel car". Presumably because there's still many kinds of diesel cars
I am not sure what context you are talking about, but one can certainly say a diesel car. It depends on what kind of reference that the speaker/writer wants to make. THAT IS THE RULE!
Let's look at some of these "other" so-called codified (based on a rule) uses of the definite article, listed on this entry.
* to refer things that are unique
This is not a good rule, as it doesn't illustrate actual usage. We can refer to unique things with the indefinite article. For instance, our planet has moon, therefore it is unique. However I can say such things as "There's a moon out tonight, so watching the meteor shower won't be so great."
* to indicate that there is enough of something (She plans to bake a pie, if she has the ingredients.)
Thank heavens we do not have to memorize this silly 'rule'! It is common knowledge (knowledge about how things work, knowledge about the world) that pies have ingredients. Note that ingredients is plural, and this post talks about singular count nouns, but the rationale for making a definite reference to plural count nouns is the same as for a singular count noun.
* with adjectives, to refer to a group of people (This is another tax break for the rich.)
Well, since just about any adjective can be used to describe a group of people, I'm not sure how helpful this 'rule' is. But since the rich is short for the rich ones, we are again dealing with a plural count noun.
* to make a generalized reference to something (Bob plays the piano.)
By "generalized," I guess the writer is alluding to making a generic reference. I mentioned generic references above in passing. Again, the category of generic reference is one that has to be tackled in a separate post. Anyway, I am not sure that linguists place the ability to play musical instruments under the rubric of generic references. So, perhaps one can say that the reason we use the when referring to the ability to play musical instruments is because we do.
A quick word on what may be the most misguided and "rule" of all
* use the for something previously referred to and specified in a narrative or conversation
We have already seen that this does not hold water to actual usage. In fact, I read that something like 67% of so-called first mentions are made with the definite article. (If you don't believe it, read any article and look at each use of the and see the number of times the is used to refer to a noun the first time the noun is used in the article.) This is because most of these uses depend on knowledge about the world. You yourself demonstrate this when you use the definite article in the following sentence:
What is the rule that allows the use of "the" in this context?
Well, golly gee, you used the before rule. But you didn't mention rule before. I am not even going to comment as to why you did. Other than to say that you did so because you wanted to.
It might be helpful to put the thought of "specific" or "nonspecific" object on hold just for moment. A broader category is "definite" and "indefinite". Which is why we have the definite article and the indefinite article. As we will see, both of these can be used to make a specific reference to an object.
In English, all singular count nouns (such as ones you have used either in your post or in comments: 'object', 'copy', 'controller', '(diesel) car', 'page', 'rule') generally require a determiner of some sort. The most common determiners are the indirect article (a/an) and the direct article (the). So we are obliged to make either a definite or indefinite reference.
The choice of making a definite or indefinite reference to a noun in not based on a rule, it is based on which kind of reference that the speaker (or writer) wishes to make. That is why any list of rules can only be guidelines. Such rules may be a help for language learners, but they can never adequately cover actual uses. Because actual uses are based on the speaker's intention: does the speaker want to make a definite or indefinite reference?
In general, the speaker makes a definite reference, when
1. He assumes or believes that his listener can uniquely identify the referent (the noun referred to), from
a) context
b) shared knowledge between the speaker and listener (the cafe we always go to)
c) knowledge about how things work (most houses have front doors, so: the front door of a house you have never seen before)
c) knowledge about the world (who won the fight tonight?)
Notice this is based on the speaker's assumption; this assumption does not have to be true.
2. At times, to introduce a new topic for discussion
Example 1: And that's when I saw the giant green peppermint in my driveway.
Example 2: Honey, I saw the cutest little dress on sale at Macy's.
3. Just to freak you out. I am serious. Language allows for a lot of creative play and/or ambiguity. So a speaker/writer can make a definite reference to an object even when he knows that you cannot uniquely identify the object. This is something you won't find on a list of rules!
Consider the following between two roommates. Jocko has not bought a new shirt in months; Tooly knows this, but is playing with Jocko:
Tooly: Wow, the new shirt you bought is tremendous.
Jocko: What new shirt?
Tooly: Psych! (Or: Gotcha!)
And the speaker can make an indefinite reference, when
1) he wishes to avoid making a definite reference (yes, dear, I saw a note on the fridge)
2) the speaker doesn't think it's important to make a definite reference (there's a book at home I want to read)
3) when the speaker does not believe that you can uniquely identify the referent (I need to order a new part for the dishwasher)
4) to introduce a new topic for discussion (The school sent a progress report about Jane today.)
5) at any other time that the speaker or writer wishes to make an indefinite rather than a definite reference, which can mean that none of the above apply.
So what's this 'specific' and 'nonspecific' reference? First a definite reference that is not generic is always a specific reference; while an indirect reference can be either a nonspecific or specific reference.
Thus
I want to buy a new car is a nonspecific reference if the speaker does not have a specific car in mind
whereas
I just bought a new car is a specific but indefinite reference, because the speaker is referring to a specific car.
Note: this post is talking about non-generic references. Generic references are a subject that requires a separate post. But they include references to a prototype of an object, such as The leopard's habitat ranges from Africa to Asia. Here the makes a definite, generic reference.
NOW:
This game requires the Classic Controller
The speaker/writer makes a definite reference. It is your job as a reader/listener to figure out why, if you can. Most the times it is obvious or automatic; the definite reference above can be made because the speaker assumes you can uniquely identify the referent (that is: know which controller he is talking about) from context, shared knowledge, knowledge about the world, knowledge about how things work. It has nothing to do with the Classic Controller being a proper noun.
But notice you also said that "This game requires a Classic Controller" seems to be correct as well. And it is. It is just that the speaker/writer made a definite rather than an indefinite reference because he wanted to.
Also note that something that is definite is usually perceived as something that is more clear or firm. When talking a product, a company is more likely going to speak about it in clear and firm terms. In other words, an indefinite reference can be seen as somewhat wishy-washy or imprecise. Not exactly the image a company wants its product to have!
as we don't say "this pump is for the diesel car". Presumably because there's still many kinds of diesel cars
I am not sure what context you are talking about, but one can certainly say a diesel car. It depends on what kind of reference that the speaker/writer wants to make. THAT IS THE RULE!
Let's look at some of these "other" so-called codified (based on a rule) uses of the definite article, listed on this entry.
* to refer things that are unique
This is not a good rule, as it doesn't illustrate actual usage. We can refer to unique things with the indefinite article. For instance, our planet has moon, therefore it is unique. However I can say such things as "There's a moon out tonight, so watching the meteor shower won't be so great."
* to indicate that there is enough of something (She plans to bake a pie, if she has the ingredients.)
Thank heavens we do not have to memorize this silly 'rule'! It is common knowledge (knowledge about how things work, knowledge about the world) that pies have ingredients. Note that ingredients is plural, and this post talks about singular count nouns, but the rationale for making a definite reference to plural count nouns is the same as for a singular count noun.
* with adjectives, to refer to a group of people (This is another tax break for the rich.)
Well, since just about any adjective can be used to describe a group of people, I'm not sure how helpful this 'rule' is. But since the rich is short for the rich ones, we are again dealing with a plural count noun.
* to make a generalized reference to something (Bob plays the piano.)
By "generalized," I guess the writer is alluding to making a generic reference. I mentioned generic references above in passing. Again, the category of generic reference is one that has to be tackled in a separate post. Anyway, I am not sure that linguists place the ability to play musical instruments under the rubric of generic references. So, perhaps one can say that the reason we use the when referring to the ability to play musical instruments is because we do.
A quick word on what may be the most misguided and "rule" of all
* use the for something previously referred to and specified in a narrative or conversation
We have already seen that this does not hold water to actual usage. In fact, I read that something like 67% of so-called first mentions are made with the definite article. (If you don't believe it, read any article and look at each use of the and see the number of times the is used to refer to a noun the first time the noun is used in the article.) This is because most of these uses depend on knowledge about the world. You yourself demonstrate this when you use the definite article in the following sentence:
What is the rule that allows the use of "the" in this context?
Well, golly gee, you used the before rule. But you didn't mention rule before. I am not even going to comment as to why you did. Other than to say that you did so because you wanted to.