Les or Des?
One of the most common questions I see on the English-to-French Duolingo is whether the definite article (le/la/les), partitive article (du/de la), or plural indefinite article (des) should be used. This confusion arises because you can omit articles in English, but you usually cannot in French.
Here are some guidelines on how you can use articles correctly on Duolingo. Note that native Francophones may use them differently, but Duo is very specific about their usage.
When you see an article, translate it directly. "The" will always be definite, "a" will always be indefinite (un/une), and when you see des in French, you can use "some" or just omit it in English. (There are exceptions. See below.)
When articles are missing in an English sentence, they must be added to the French translation. The definite article can be used if one of three conditions is met:
- When referring to particular nouns that are known to the speakers.
- Before the subject of a sentence to state general truths about it.
- Before the direct object of a verb of appreciation (like aimer) to express like/dislike.
If any of the above is true, then use the definite article. Otherwise, use the indefinite or partitive, depending on whether or not the noun is countable. In most cases, use du or de la (partitive) for singulars and des (indefinite) for plurals.
- I like wine, but I am drinking milk. — J'aime le vin, mais je bois du lait.
Both articles are missing in the English version of this example. Aimer expresses fondness for wine, so le vin should be used there. However, boire is not a verb of appreciation, so the partitive du should be used on the uncountable lait.
- Cats are animals. — Les chats sont des animaux.
This is a general truth about cats, but #2 above can only apply to subjects, so only chats takes a definite article here. Animaux are countable, so the indefinite is used.
- He likes to eat meat. — Il aime manger de la viande.
This is a tricky example because meat is the direct object of manger, not aimer. Thus, #2 does not apply and viande cannot take a definite article.
Here's another example: "Local women wear black dresses." Which articles should we use? Think about it for a moment. The correct answer is at the bottom.
- In negations, indefinite and partitive articles all become de except with être or if you want to stress the negative aspect.
- For countable nouns, sometimes "some" should be translated as quelque or certaines. These words denote some subset of a larger group.
- If there's an adjective in front of the noun, des becomes de.
- If you want to learn more about the partitive, look here.
- Local women wear black dresses. — Les femmes locales portent des robes noires.
This sentence is making a generalization about local women, so femmes takes the definite article. Robes noires does not, however, because it's not the subject nor the object of a verb of appreciation. However, consider this similar example where les can be used on both:
- Local women like black dresses. — Les femmes locales aiment les robes noires.
I'm having trouble with this Duolingo question.
The English sentence is "happy employees are good employees". The default French translation is "des employés heureux sont de bons employés".
My issue is that in this sentence "happy employees" refers to the complete set of happy employees, i.e. all of them, whereas it's my understanding that the French "des employés heureux" refers to a subset, i.e. not all of them, only some.
"Les" is also accepted, but I don't understand why "des" would be considered correct, and why it would be given as the default.
Edit: Sitesurf to the rescue!
This post was excellent! I have read the article on about.com several times, but your post was much stronger in explaining the point of generalisations. This was something that Duolingo had almost taught me, but that I had quite managed to decipher on my own. With this knowledge, I can now proceed with confidence, and perhaps stop losing some of those cheap hearts.
What about generalizations that do not apply to all of a certain group, but are just a descriptive statement. For example: "Do cats live in America? Yes. Cats live in America." The sentence, "Cats live in America." Would become "Les Chats vivent en Amérique." (even though not all cats live in America) right?
What if there is no context? For example, in a storybook about a made up animal called "Les gompgompes". If the book said, "Les gompgompes vivent en Gompleterre." Would the french reader take that to mean "All the gompgompes live in Gompleterre." Or just "The Gompgompes in this story live in Gompleterre, but gompgompes may live elsewhere." Or could it be either?
Unless you're talking about "the (specific) cats" referred to earlier in the conversation, the thing to do is to consider whether you're talking about "all cats" or "some cats".
If you were asking about all cats, you'd ask "Est-ce que les chats vivent en Amérique?" Otherwise, you'd ask "Est-ce que des chats vivent en Amérique?" The answer would be "Oui, des chats vivent en Amérique."
It's a little confusing, partly because the English is ambiguous. We make assumptions because we know that, when speaking of (all) cats, it's true to say that cats live almost everywhere in the world, but it's also true to say that (some) cats live in America, and yet we don't clarify whether we're talking about all or some.
In your story (which I hope you'll complete so I can read), the construction with "les" states that all gompgompes live in Gompleterre, unless there's a very clear indication that you're speaking of the particular gompgompes that have already been mentioned, but not all gompgompes.
Thanks for the input.
My confusion arose from a couple of exercises. "Elephants live in Asia and Africa" was translated with "Les éléphants vivent en Asie et en Afrique" and "Des éléphants..." was not accepted (even though not all elephants live in Asia and Africa).
And one of the moderators said that "Birds live in Europe" would translate to "Les oiseaux vivent en Europe" (again when not all birds live in Europe).
I translate some formal communications for my company from a french vendor (letters, advertising, etc), and I just want to be sure of the little things like this. I assume using "les" instead of "des" (or vice-versa) in the wrong sentence of a legal document could cause problems.
Here's my question to Sitesurf on that page, just posted:
Sitesurf, is this implying all birds? And if so, isn't it more true to life to say "des oiseaux vivent en Asie et en Afrique"?
I can see the case for "les" for elephants, because that's at least where they're indigenous, even though some live in zoos and sanctuaries around the world.
The trouble is that with English, it's ambiguous, but I think, because we have life experience as context, we understand the sentence about birds to mean "certain birds".
Let's see what she says.
Sitesurf's response is a bit more nuanced than I expected and suggests that "des" and my example above about "some cats" is unlikely as a general statement:
[...] The above ["les oiseaux..."] is a blanket statement, but you and I have life experience telling us we can find birds on other continents as well.
"Des oiseaux vivent en Asie et en Afrique" sounds a bit weird and I have had to frown a bit to try and find what this could mean. By itself, it does not mean anything relevant.
Yet a bit of context can make it acceptable, even something minimal like "Des oiseaux [+ characteristic] vivent Asie et en Afrique", so as to justify their limited number. "Des oiseaux à bec rouge" could do the job (although I have not checked whether it is true or not).
Otherwise, the specificity can come at the end of the sentence, like "Des oiseaux vivent en Asie et en Afrique dans des volières de bambou". In this case, you can use "some" in English or the alternative "Certains oiseaux" in French.
I'm going to follow up with her and will post again here when I receive a reply.
Here's a link to the whole discussion with Sitesurf:
De rien! If you or anyone else has any ideas on confusing topics that I can address in the future, I'm taking suggestions.
Any clue where I can learn how to conjugate verbs? Are there any rules? I have such trouble when I see their infinitive states.
Have a look at verbs and list discussions referenced here. Many verbs are regular, which means they are made of a stem that doesn't (or almost) change, it is the base that usually has -er, -ir or -re suffix added to the end of it to form the infinitive, and you only have to substitute that ending for the appropriate ending, which depends on the grammatical person and the verb tense and mood. It becomes second nature after a while. Others are irregular and should be learnt by heart. Unfortunately, there are many irregular verbs, although some still follow some patterns. Many natives have to check in a conjugation dictionary once in a while to find the correct way to write a verb, especially in seldom used tenses. A good online one is WordReference. If all of this isn't enough, have a look at this introduction to French verbs.
Sorry, but I didn´t understand this statement: If there's an adjective in front of the noun, des becomes de. Could you give me an example?
alecino- When the adjective is in front of plural nouns, always de : de belles robes, de belles filles, de beaux bébés.
This confusion killed me all throughout high school French class. Merci beaucoup.
There are also cases when articles are omitted in French as well...could you also explain these?
Certainement. These are pretty rare, so you'll just have to memorize them. Articles are...
- Optional between être and professions. For instance, je suis médecin.
- Optional between parler and the names of languages. For instance, je parle anglais. Note that this isn't true for other verbs (e.g. savoir) and that language names are not capitalized.
- Optional with adjectives of number. For instance, plusieurs pays or deux chevaux. Including an article with these may be forbidden or may change the meaning.
- Optional after certain prepositions. For instance, sans eau or après déjeuner.
- Optional after devenir. For instance, devenir roi.
- Omitted when using de to indicate a larger whole something came from, the way something was made, or the purpose of an object (see here).
- Omitted after some expressions ending in de. For instance, beaucoup d'eau or avoir besoin de nourriture.
- Replaced by a possessive adjective. For instance, votre chien.
EDIT: I should point out that it's not that French requires articles before most nouns, but rather that it requires determiners, which are a broader category that includes articles. Adjectives of number and possessive adjectives fall into this category. Also, this now has its own thread.
Optional if preceded by sans, for example "sans eau"
Optional if the verb is devenir, for example "devenir roi"
Also if a possessive is directly before a noun the article is omitted:
C'est votre chien. It is your dog.
there are also cases when articles are omitted in french as well...could you also explain ?
Here's a web page that lists some scenarios:
To those possibilities I would add the case of brief lists:
Very well written and quite helpful. I still make these kinds of mistakes, but not as often as I used to. The repetitive exposure on Duolingo is starting to give me a "feel" for it, which is what I need when speaking. It has to come naturally. But this will be helpful when writing, when I can pause to consider which article I need to use.
J'ai un question sur utiliser les vs. des. In this sentence, « He sells vegetables in this store, » I mistakenly think it is supposed to be: « Il vend les légumes dans ce magasin. » This is because he sells vegetables (generally) in this store.
But it is supposed to be this: « Il vend des légumes dans ce magasin. »
Is this about partitive vs. definite or is it about the verb « vendre » ?
Aren't there some verbs which require de/des/d' in following, such as « manger » ou « avoir » ? Or am I still mistaken? Let me know if you need me to clarify. Merci pour votre temps.
Salut Kat! C'est une bonne question. Verbs don't usually affect what article one must use. Some verbs, like aimer, happen to be associated with generalized definite articles more frequently, but that's just a coincidence.
In this sentence, you are actually not generalizing about légumes. I gave a terse explanation above that doesn't appear to be sufficient, so here's the long version: the French use the definite article for the gnomic aspect (or universal aspect), which expresses general truths. You have to be careful, because this doesn't apply to anything that we'd call a generalization in English. It can only be used to give the definite article to a particular noun when we're expressing a general and universal truth or sentiment about that noun. You'll get a better sense for this as you become more experienced in French.
So, in your example, you're correct that you're generalizing that he sells vegetables. But this doesn't state any kind of general truth about vegetables. It just means that he sells some undefined set of things that happen to be vegetables, and that's why we use the partitive des.
Now, let's say that you're explaining supermarkets to a foreigner. You say "Supermarkets sell vegetables." One of these nouns is operating in the gnomic aspect. Which one? It's certainly "supermarkets", because you're stating a general truth about them--that they sell vegetables, among other things. So this would be « Les supermarchés vendent des légumes. »
There are some verbs that require de/d' to complete a meaning, but these aren't partitive articles. They're just the preposition de. For instance, "to think about" (as in have an opinion) is penser de.
Bonjour encore DXLi, merci beaucoup pour votre réponse.
You make an entirely reasonable point that generalizations are treated/understood differently between English and French. I should get used to using the universal aspect. Perhaps this is my homework. I have to train my brain to think this way in English, so that I'll use it easily in français.
I may also have thousands of follow-up questions, the more I practice it, but this is just me thinking out loud... The more I practice it, the more I have the feel for it.
Quick thought: I want to know this, if I eat beans (generally), then would I say, « je mange des haricots, » rather than, « je mange les haricots » (the beans we're already talking about)? If I generally buy pink things, then would I say that j'achète des choses roses (heh, c'est amusant dire) rather than « j'achète les choses roses, » ... vrai ?
....And if Americans generally buy pink things, puis on dit, « Les Américains achètent des choses roses, » vrai ? Et if stores (generally) sell things, then les magasins vendent des choses.
Merci, et désolé about my ongoing confusion. I don't mean to attack the language, in case that's what it sounds like. I probably should, however, loosen my mind and practice/apprendre the universal aspect in my everyday thoughts.
The logical explanations are very helpful in reaching an understanding of when to choose between these forms of an article. Over time I imagine one who is fluent is able to distinguish the correct choice also by sound, based on what one hears, having heard the correct usage before. Is there anything helpful to be said about determining what sounds right? Could there be an exercise of a series of sentences in French illustrating various guidelines, an expansion of the example above about black dresses to learn what sounds right?
Yarouge--I don't know the answer, that is what to write as an example of des becoming de. I lost the train of thought. I hope someone responds to your good request. I'm in over my head. Best wishes.
I posted a question in a lesson asking why "he often helps others" is translated to "il aide souvent les autres" (instead of "des autres"), and then I found this page -- but I don't see a definitive answer here.
I wonder if there is a definitive answer in this case, or if (a) some uses are just idiomatic, or (b) there is sometimes a choice as to whether to use les or des, depending on the speaker's own conceptualization of the matter, even though nothing really rides on the distinction.
Thoughts? Can someone set me right?
Des autres is wrong here. We usually use les autres for both "others" and "the others". But when we explicitly want to talk about a subset of the others, des (plural indefinite article) gets shorten to de, itself elided to d' : d'autres. The only way to have des in front of autres is if this des is a contraction of the preposition de and the plural definite article les : il a peur des autres (il a peur de - les autres).
In case you'd understand better with the explanation from someone else, check the best answer to this question (in French).
Thank you, you've explained it clearly enough for me yourself.
(However, something I find interesting about the post that you've linked to is that it reverts at times to the determiner that would be used in a "normal" case to explain what the "unusual" construction used with "autres" is getting at, if I can put it that way. In any event, I take it that "autres" can be thought of as something of a special case.)
To follow up on a couple of points, and perhaps help solidify my understanding:
If I want to say "he is afraid of others", I should say "il a peur des autres", as you've written above. And if I want to say "he is afraid of eggs", my sense is that should I say "il a peur des œufs" ("il a peur de", plus "les" because of the general sense of the sentiment). But could it possibly be "il a peur d'œufs"?
And Duolingo teaches "tuer des animaux", but I take it "tuer les autres" is the correct form with "autres", while "tuer des autres" is incorrect. But what about "tuer d'autres animaux"? Does that make sense? And what about just "tuer d'autres", using "autres" on its own as a pronoun? I'm guessing these last two are both okay.
The rule is the same whether autres is a pronoun (when it stands on its own to represent some people or things) or an adjective (when it only qualifies a substantive that follows). So you are right about everything in your last paragraph (but for the fact autre can't be a noun, only a pronoun).
You can't say il a peur d'oeufs for the exact same reason why you can't say il a peur d'autres. It's avoir peur de X, plus the definite article les and either the noun oeufs or the pronoun autres. But when autres is an adjective and it is used with a plural indefinite article (des), it acts like any other adjective with des : des gets reduced to de (and it elides since autres starts with a vowel). See the rule about that as the last point in this article.
And about the post I linked, it's not a normal case vs an autres case, it's just showing the intermediate articles before the shortening to help us understand better.
Okay, fantastic. And right, pronoun. (But grammatically treated no differently from a noun or noun phrase, which is the sense I was getting at. Though it can be a noun, as in "the Other", says Larousse. But that's neither here nor there.)
Regarding your second paragraph, wonderful! I think I've got it, though I can almost guarantee I'll get it wrong many times in the future.
As for your last point, I see that now. I misunderstood at first, but I'm happy to have been able to read a post in French. On that note, are there any grammar books or grammar book publishers you can recommend, off the top of your head, like a Longman or an Oxford, but in and for French? It would be nice to have it all between two covers.
Thanks very much for your help!
The reference when it comes to French grammar is Maurice Grévisse's Le bon usage, but that might be a bit overkill.
A bit more accessible (both language-wise and price-wise) is Bescherelle's La grammaire pour tous. They also make an excellent conjugation dictionary, which is the reference in the French speaking world.
In fact I have a Bescherelle conjugation dictionary (borrowed, as mine from years ago seems to have disappeared), which I've always just thought of as "a Bescherelle" -- it didn't occur to me that they might publish a comprehensive grammar.
As for overkill, I'm all for it. That's a pretty steep price on the Grevisse, though! Worth it, I'm sure, but perhaps I'll get the Bescherelle for now, see how dedicated I am, and graduate to the Grevisse...
this is great. thanks. Can I suggest that simple examples be given EACH time a statement of fact is made? For example, when you say:
"When articles are missing in an English sentence, they must be added to the French translation. The definite article can be used if one of three conditions is met:
When referring to particular nouns that are known to the speakers. (PROVIDE SIMPLE EXAMPLE) Before the subject of a sentence to state general truths about it. (PROVIDE SIMPLE EXAMPLE) Before the direct object of a verb of appreciation (like aimer) to express like/dislike." (PROVIDE SIMPLE EXAMPLE)
I know it makes the post longer, but I do really think we students would benefit from the examples.
thanks for listening
Hello, Recently i did some exercise with the following example: Proscrivez le chocolat, les bonbons et les autres sucreries, les sauces et surtout pas _d'_alcool. My question is why it is wrong to use du chocolat, des bonbons, des autres sucreries etc, when it is an indefinite quantity?
When implying all of something, in general, use the definite article:
- Prohibit (all) chocolate (in general), (all) candy and other sweets (in general), (all) sauces (in general), and especially no alcohol (at all).
The ending is stylistically problematic, in my view. Prohibit no alcohol? In other words, allow all alcohol?
In any event, the negative part of the sentence is a little tricky. Note that the last item is partitive because you're implying "allow/consume no (indefinite quantity of) alcohol (at all, in any amount)".
This is incredibly helpful! I am a brand new high school French teacher without much teaching education, and I have been pulling my hair out trying to figure out how to explain this to my students. I am definitely going to follow you on Duolingo in the hopes that you can help with other confusing subjects!
What about "J'étudie les éléphants" ? According to your rules, nouns of direct objects should only be preceded with definite articles when used with verbs of preference.
When "all X in general" is implied, the definite article is required.
Thanks very much for this! Usage of du/des/de and les is something I struggle with, so. :) Cheers!
"des" is just the plural for "un"
un livre - a book des livres - some books le livre - the book les livres - the books
Des can be either an indefinite article (as per your example) or a partitive one (as explained by DXLi). Although it is not always evident to tell them apart. So des can be the plural of either un / une or du / de la / de l'.
There is an exception about the use of 'de' in negations. If the verb is être the article remains the same.
J'ai un question. Il concerne 'les' vs. 'des.' DuoLingo dit : « Il cherche des mots dans les dictionnaires » traduit à « He searches for words in dictionaries. » Mais, mon question, c'est que il ne cherche pas dans toutes les dictionnaires ? Juste quelque. Aidez-moi, s'il vous plaît.
Merci et bon week-end,
This article is useful, but it's a shame that the only example you have given of using a definite article is with an appreciative verb, which is an unusual case. I've been desperately trying to find somewhere online which illustrates your point #1 about the "nouns known to the speaker" as I've had two friends who have formally studied French (and one is a language tutor) tell me that there is no difference in French between "ils trouvent la nourriture" and "ils trouvent de la nourriture". I was certain there was a difference, but this potentially broken question in Duolingo seemed to indicate there wasn't. (The "answer" given at the top of the linked the forum page was ""Ils trouvent la nourriture." - no not one of the given answers - yes it did say "ils" not "elles" :-P )
The OP contains three different examples of the use of a definite article, not just one, so I'm not sure what you mean by that. As far as "nouns known to the speaker", this refers to the most common use of the definite article, which is to refer to a specific thing that has been identified to all participants in the conversation.
Despite what your friends say, there is a difference between the partitive and the definite in both French and English. For instance, "the meat" is a specific, identified portion of meat, while just "meat" (or "some meat") can refer to any meat or even all meat. Consider the following examples:
Example 1: You want to ask someone if he's a vegetarian. You would ask "Do you eat meat?". Asking "Do you eat the meat?" would be silly.
Example 2: You are cooking some meat. Your friend calls you to chat. You can only say "I'm cooking the meat" if you have already mentioned it or if your friend knows about it otherwise (e.g. he bought it for you). If your friend has no idea that you have meat, you have to say "[some] meat" instead of "the meat".
As for the exercise you've posted, this is just due to inconsistencies in the course. There are thousands upon thousands of exercises in the course, all of which are manually edited. There's no word-for-word translation checking. We're working on fixing this; sorry!
Thanks :-) ... so, just to clarify ... in that screenshot I posted... the "correct" answer I gave, should have been wrong, right?
Part of my friends' confusion might have been the idea that there are certain kinds of substances that you can only speak of in an undefined quantity and never in the specific (definitive). My language tutor friend said that "nourriture" is that kind of word, what he called an "uncountable noun". (He's not a native French speaker, so maybe he's rusty.)
I am very doubtful of that as I cannot think of any such concept in English, and would be surprised if French was so limited to not be able to refer to specific pieces of something physical.
Aye, the correct answer should be Ils/Elles trouvent la nourriture.
You're right that there are countable and uncountable nouns, but all nouns can take definite articles. An uncountable noun with a definite article refers to a specific portion of that uncountable noun. However, uncountable nouns cannot be plural (with a few exceptions, such as pâtes), and only uncountable nouns can take partitive articles.
The notion of uncountable nouns exists in English as well (like "water"). And countable ones can definitely take partitive articles. It's not seen often, but it can, as per DesertGlass' example. The difference is that only countable nouns can take numeral articles (usually, there are some context specific and rare exceptions, as in every French rule ;-)). It may be confusing to an English speaker because you have the distinction between the indefinite singular article and the numeral article indicating one object ("a" vs "one") whereas French only has one word for the two functions (un).
EDIT : As per DXLi's explanation, when countable nouns take a partitive article, it's because they're used as a "mass" noun, or the matter instead of the stand alone (and countable discrete) object.
Great!! Thanks for taking the time to explain that. It's to Duolingo's credit that it had managed to instil this into me already so that when an inconsistent answer came up I knew something was amiss.
Um, when you say "only uncountable nouns can take partitive articles" ... ... isn't "je mange de la tomate" using a partitive article? But "tomate" isn't an uncountable noun, just used in an "uncountable sense" ...
This difference is mostly semantics. Almost all nouns that can be used in a mass sense also can be used in a discrete sense, so when we say "mass noun", it essentially means the mass sense of that noun. In your example, de la tomate means an uncountable mass of tomato, while une tomate means a particular tomato. So even though tomate can sometimes be a count noun, it is also considered a mass noun when used with a partitive.
There's some debate about whether or not countable nouns can take partitives, and most of this comes from the question of whether or not des is a partitive. Regardless, for singular nouns, partitives can only be used for mass nouns. For instance, j'ai de la robe is nonsensical.
Thanks for the info DXLi. Let me stress I'm coming at this from a completely innocent angle and have no doubt that you guys know your stuff, it's just hard to communicate it sometimes. (or maybe I'm just stupid)
I would like to ask - with the greatest respect - for you to give me a direct response on which of these two things you've said is the French rule - unfortunately to me they appear to contradict each other, leaving me confused.
a) "only uncountable nouns can take partitive articles"
b) "partitives can only be used for mass nouns"
You haven't mentioned "mass nouns" before, but I understand that "tomate":
- is not an uncountable noun as it can be pluralised
- can be used as a mass noun as it can be described like a substance
DXLi, you are right about that (countable nouns used as "mass nouns"). And about des being a partitive, I think it can be both a plural indefinite article and a partitive one, depending how it is used.
"Uncountable noun" and "mass noun" mean the same thing here, DesertGlass. Sorry about that confusion.
Bastou, I agree with you, though the Duo French team's official stance is that des is exclusively indefinite except when used with plural-only mass nouns like pâtes.
Aha! I'd give your post an "upvote" but that would change the response order ;-)
Going forward, I will remember the partitive rule with the term "mass noun" instead - and will define that as nouns that can either not be pluralised OR can be used as an uncountable mass. I think all the cobwebs of confusion have been swept away, and indeed it seems to match with what I thought in the first place :-)
Where you say:
This is a tricky example because meat is the direct object of manger, not aimer. Thus, #2 does not apply and viande cannot take a definite article.
Don't you mean #3 (vs. #2), since the issue is about aimer vs. manger?
So to say "there are mosquitos" in french you would say "il y a des moustiques"?
Sentence 60 it's in plural and the answer is singular..How it's work.
If I understand this correctly I will need the definite article when expressing an opinion: J'aime le vin. How do I then distinguish between liking any wine and liking some particular wine?
Thanks. I thought that "ce" required that I more or less were holding the bottle or glass when speaking?
The meaning of "ce" is a little loose (or at least contextual). As a determiner, for example, the appropriate translation might be "this" or "that", or some other related word, depending on the context.
I never heard that, but I’m just a student, not a native French speaker.
What about in the sentence "Comment as-tu réussi à apprendre beaucoup de langues?" Why is "de langues" not "des langues"
There are many idioms that use “de” such as “beaucoup de”, “assez de” and “trop de”. I think of the “de” as being part of the idiom “beacoup de “
«Beaucoup»is usually followed by «de». The only time it would be followed by «des » would be when referring to a specific group of items.
For example, if we say "A lot of dogs are gentle with children." We are not talking about a specific group of dogs, it's just a generalization. So, it would translate to "Beaucoup de chiens sont gentils avec les enfants."
But, if we are talking about a specific group of dogs: "A lot of Marie's dogs are mean." It would be "Beaucoup des chiens de Marie sont méchants."
So, if it is a generalization use «de». If it is referring to a specific, defined set, «des».
We do it this sometimes in English too: "He speaks a lot of languages." (no "the" before the generic group of languages).
"A lot of the languages he speaks are romantic." (add a "the" before the specific set of languages)
I've been wondering about this "les in a general not-opinion sense" for a long time, and I think this was just the information I needed. So it's only used to speak generally of the SUBJECT of a sentence.
I think "only" is too absolute. One of my questions on this page was about the sentence "il aide souvent les autres". While "les autres" is perhaps something of a special case, it demonstrates that it can make sense to refer to the (direct or indirect) object of a sentence in a general sense, requiring "les" instead of "des".
Okay, here's another one, there is a lesson to translate "I have guidebooks of all the European capitals" It only seems to accept answers with "les" for example: "J'ai les guides de toutes les capitales européennes."
Why "les" in this case? And depending on context, couldn't it be "des"?
I think that "les" would make more sense here, because of the "all of the ...", which suggests a specific guidebook per European capital. But I can also see "des" working.
Basically, do you want to say "I have some guidebooks of all ..." or "I have the guidebooks of all ...". Of course, in English both "some" and "the" can usually be dropped (as they are in your English sentence).
I believe we tend to think of the guidebooks singularly on a per city basis. Each city has its own guidebook, which is the guidebook for that particular city.
Of course, there might be an indefinite number for each city, in which case "des" would make sense, but we don't necessarily bother with that consideration when making the general statement.