What form of to be would be right to use in this case?
Why drug abuse in general and cannabis consumption in particular is/are dangerous for your health.
English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English. It only takes a minute to sign up.Sign up to join this community
Disclaimer: I'm not a native English speaker; I'm a native French speaker and English to French translator. Therefore, I had to study the grammar of both languages a bit more than if I had a different occupation. What follows is a strictly personal take on the question.
The answer below considers the question from a grammar and style point of view. More specifically, the gist of my contribution here is that a correct usage of commas reveals the answer to the question without difficulty.
I believe that commas are missing in the OP's sentence. When removed, commas have the peculiarity to cause ambiguity, which then creates confusion, which in turn leads to the false impression that otherwise simple questions are complex or difficult questions. The question wouldn't have arisen had commas been placed correctly in the first place.
Let's put commas where I (and I'm by no means a grammar authority) think they should have been put:
Why drug abuse in general, and cannabis consumption in particular, is/are dangerous for your health.
“is” would be my answer. The details explain why.
I remember reading somewhere what an English writer said about commas: they shouldn't be peppered all over the place. Although that may be fine and even sometimes true, commas have (or should I say had) a role that modern English tends to forget. First, they denote a pause when the sentence is read out loud (“when in doubt, read it out loud” would be my advice). Second, they surround and delimit secondary clauses. Third, they may separate the main clause from a subsequent secondary clause. Fourth, a single comma may separate independent clauses in the same sentence. I can't think off the top of my head of other roles/functions with respect to sentences.
 To me, and this is only personal experience from being a native French speaker, the commas also separate the main clause of the sentence from the rest, which adds context and superfluous but useful content.
Let's rewrite my sentence  above and keep only the main clause. We get:
The commas also separate the main clause of the sentence from the rest.
If you were to look for the main clause of the sentence in the question, you would end up with:
Why drug abuse in general is/are dangerous for your health.
Does anyone really think that “are” would be a valid option here?
Moreover, "in general" and "in particular" often go hand in hand. (It's what I would call a standard construct; the correct English wording is probably different.) And in that case, "and" is a conjunction often used in that construct but this does not mean that the subject of the sentence is a plural subject. Actually, I'd wager that “and [...] in particular” is a parenthetical element of the sentence (see the usage note of and at dictionary.com). Try removing and in the in general, and […] in particular construct and see how it feels weird:
The nature of change in general, of motion in particular, is not a novel issue.
When trimmed to the main clause, the sentence retains its “main” meaning:
The nature of change in general is not a novel issue.
Add the “superfluous but useful” (i.e. the parenthetical element) in there and you get the original sentence:
The nature of change in general, and of motion in particular, is not a novel issue.
Why would to be suddenly change forms then?
Last point, with respect to example sentences in another answer: those tiny punctuation signs (commas) may not seem like much but they matter. They usually come in pairs, except when placed at the beginning of a sentence after a time phrase, a purpose phrase or phrases of similar grammatical function, and after a main clause. They don't come in one single occurrence like in:
Lack of exercise, and eating fatty foods are bad for your health.
In my eyes, and according to the English grammar that I learnt at school, that's not correct. You either have two commas or you have no commas at all:
Lack of exercise, and eating fatty foods, are bad for your health.
Lack of exercise and eating fatty foods are bad for your health.
In the first case (two commas), you are stating that fatty foods are an instance or consequence of "lack of exercise". Are they?
In the second case (no commas), you are explicitly stating that the subject is plural. are is then the required form of to be.
I've learnt that there shouldn't be a comma between the subject and the verb. Does the following feel right?
Joe, went to a party last night.
A plural subject shouldn't be separated by a comma either except when an enumeration of more than two elements is involved:
Joe, and Lucy went to a party last night.
But these are valid because of the enumeration:
Joe, Martin and Lucy went to a party last night.
Joe, Martin, and Lucy went to a party last night.
Each time I read sentences such as the one below, I think of that English writer about commas not being to be peppered all over the place (like they are in Latin languages such as French) and of the current tendency of modern English to forgo commas completely:
Life in general and human life in particular is a phenomenon whose existence is restricted to an infinitesimally small part of the universe known to us.
Because that feels so much more right in speech, I would always add two commas in there and write:
Life in general, and human life in particular, is a phenomenon whose existence is restricted to an infinitesimally small part of the universe known to us.
To sum up, my answer is “is” because those tiny things called commas matter. Unfortunately, they seem (personal opinion again) to be disappearing from current usage, both in writing and in speech.
The OP's sentence appears to be adapted from a Ph.D project
The etiology of schizophrenia is highly complex, involving both genetic and environmental risk factors in multiple combinations. Among the environmental risk factors, drug abuse in general, and cannabis consumption in particular, play a key role.
Drug abuse and cannabis consumption are just two of the risk factors which may lead to schizophrenia.
The verb are is plural because the author lists two separate risk factors.
But in the OP's example there is no context, there is no premise, we only have the bare statement to go on. The fragment phrases “in general”, and “in particular”, will be omitted for reasons of clarity and because they are not essential to the sentence's construction.
- Why drug abuse, and cannabis consumption, is dangerous for your health.
In this sentence, the two elements ‘drug abuse’ and ‘cannabis’ are singular nouns. Taken individually, the clauses ‘drug abuse are ...’ and ‘the consumption of cannabis are ...’ would be ungrammatical. On the other hand, many native speakers instinctively opt for the single verb when it agrees with the closest noun or noun phrase in that situation. For example,
A. Fresh fruit and organic rice is healthy.
A. Exercise in general, and a diet of fresh fruit and vegetables is good for your health.
The verb is normally singular when two subjects in a clause refer to the same person or thing,
e.g. Bread and butter is the only food he eats.
B. Fish and chips is a British institution.
Joanna’s rum and coke was equal parts rum and coke. source
C. Lack of exercise, and eating fatty foods are bad for your health.
In speech, I strongly doubt anyone would notice or point out the verb disagreement in sentence No.1. However, in writing, and when a certain formality is required, I would recommend that learners use the plural verb when two separate subjects are joined together by and.
- Why drug abuse, and cannabis consumption are dangerous for your health
If we look back to the original statement, the verb play is plural, not singular.
The following examples show that authors usually prefer the plural verb in similar constructions.
Throughout non-communist Southeast Asia communism in general and China in particular have long been the ubiquitous targets of threat perceptions which in very recent years have accorded Vietnam and even the Soviet Union... source
The evidence we marshalled at the time was, frankly, a bit thin. However, time, and this conference in particular, have replicated this finding.* source
The Netherlands and Germany in particular have become places where, within a relatively short period, a host of African-initiated churches have been founded. source
The point is that even when the subect is clearly more than one, using the singular verb is relatively common in speech if the last subject is singular or is perceived to be; but in formal writing, it is always better to use the plural verb when two subjects are joined by "and" although there are a few exceptions, which I have listed above.
The following interesting extract from M-W deals in depth with the issue of compound subjects and verb agreement. According to their guidelines (rule 1) you should use the plural verb in your sentence because you are referring to two subjects, but if you consider the two subjects as part of a single unit (exception 1) the singular verb is correct.
Here are the rules and the exceptions (probably not definitive ) on this grammatical issue:
Most ESL and EFL learners know that the verb's number in a sentence must match the subject's number. That is, if the subject is singular, the verb must be singular, and if the subject is plural, the verb must be plural:
- SINGULAR SUBJECT: The dog barks every morning. PLURAL SUBJECT: The dogs bark every morning.
This is called subject-verb agreement.. In simple sentences, like the ones above, it is relatively easy to check the subject-verb agreement.But subject-verb agreement is more difficult to determine in complex sentences and in questions.
When a sentence has more than one subject per verb, those subjects form a compound subject. Compound subjects can be singular, plural, or a mix of both:
- TWO SINGULAR: The dog and the cat bother me.TWO PLURAL: The dogs and the cats bother me.ONE SINGULAR, ONE PLURAL: The dog and cats bother me.
Compound subjects can also be joined by "and," "or" (sometimes "either...or"), and "nor" (sometimes "neither...nor"):
- The dog and the cat... (Either) The dog or the cat... (Neither) The dog nor the cat...
Deciding which verb to use can be tricky. Here are the general rules:
Rule 1. A compound subject whose parts are joined by and usually takes a plural verb regardless of whether those parts are plural or singular:
- TWO SINGULAR: The dog and the cat bother me. TWO PLURAL: The dogs and cats fight all the time. ONE SINGULAR, ONE PLURAL: Joe and the kids need me.
Rule 2. A compound subject made up of two singular parts that are joined by or or nor takes a singular verb:
- (Either) James or John knows who is coming to the party. (Neither) James nor John knows who is coming to the party.
Rule 3. A compound subject made up of one singular part and one plural part that are joined by or or nor must use a verb whose number matches the number of the part of the subject that is closest to the verb:
*CORRECT: (Either) The dog or the kids were making a racket downstairs. [kids were...].
CORRECT: (Either) The kids or the dog was making a racket downstairs. [dog was...]
INCORRECT: (Either) The dog or the kids was making a racket downstairs. INCORRECT: (Either) The kids or the dog were making a racket downstairs.
CORRECT: (Neither) Joe nor the kids want pizza. [kids want...].
CORRECT: (Neither) The kids nor Joe wants pizza. [Joe wants...]
INCORRECT: (Neither) Joe nor the kids wants pizza.
INCORRECT: (Neither) The kids nor Joe want pizza.
There are two exceptions to these rules.
Exception 1. When the parts of a compound subject are joined by "and" but are generally thought to be a single unit, they take a singular verb, not a plural verb:
- CORRECT: Peanut butter and jelly is my favorite.
INCORRECT: Peanut butter and jelly are my favorite. CORRECT: Two and two equals four.
INCORRECT: Two and two equal four.
Exception 2. When the parts of a compound subject are joined by "and" but the subject is modified by the words "each" or "every", the subject takes a singular verb, not a plural verb:
- CORRECT: Every boy and girl gets a merit certificate. [every boy gets...every girl gets].
INCORRECT: Every boy and girl get a merit certificate.
CORRECT: Each business and restaurant has to display a business license. [each business has to...each restaurant has to...].
INCORRECT: Each business and restaurant have to display a business license.
You should use is. The subject is conceptually singular (talking about only one thing) even if there is a specific subset of this concept mentioned. The presence of the word and does not determine which verb to use. Your sentence can be correctly paraphrased as
Why drug abuse in general (and cannabis consumption in particular) is dangerous for your health.
The following authentic uses show that the structure NP in general and NP in particular is used with is, and the use of commas is stylistic depending upon the length of the noun phrases.
Example 1: '...and has proposed instead that contemporary science, and evolutionary theory in particular, is compatible with the existence of God.'
Example 2: 'Life in general and human life in particular is a phenomenion whose existence is restricted to an infinitestimally small part of the universe known to us.'
Example 3: 'The nature of change in general, and of motion in particular, is not a novel issue.'
Example 4: 'Education in general and higher education in particular is seen as having a constitutive role in relation to the significant recent conceptualization of development which emphasizes the achievement of human functionings and capacities.'
Are is used when both noun phrases are plural:
Freshwater shrimps and crayfish in particular are used for food ...
Your phrase is a simple case of a compound subject each of whose components is discrete, and which together do not constitute a commonly used single entity. The correct verb form is the plural:
Why drug abuse in general and cannabis consumption in particular are dangerous for your health.
There is nothing in the sense of this phrase that leads us to wonder whether these two phenomena are meant to be considered dangerous only as a class and its subset; the ineluctable conclusion is that the writer intends us to believe both that drug abuse in general is dangerous, and that cannabis consumption, a class of that abuse, is dangerous "in particular". It is both of these abuses, the general and the particular, against which we are warned. The conclusion that we are being warned against two phenomena is inescapable. (This is especially true because there are those who hold that consumption of cannabis is less dangerous than consumption of other drugs, and the intent of the writer may be to state that this differentiation is without merit.)
Either drug abuse in general or cannabis consumption in particular, taken individually, would call for the singular form is. Together, they constitute a compound subject. That a compound subject takes a plural verb is attested to in any number of authoritative grammars.
This is therefore the simplest case of subject-verb agreement. It's hard to think of a more credible source than Michael Swan's Practical English Usage, in which he writes on p. 532:
When two singular subjects are joined by and, the verb is normally plural.
Alice and Bob are going to be late.
But note that some phrases with and are treated like single ideas, and used with singular verbs. Your toast and marmalade is on the table.
Mr Swan's example would be no less illustrative of this principle if it were phrased as:
The Smith family as usual and Bob Smith uncharacteristically are going to be late.
Although the sentence has two nouns, abuse and consumption, it indicates a concept of idea or a oneness of idea that drug abuse is dangerous for your health. So the use of "is" is appropriate in the sentence.
Cannabis consumption can also be called a drug abuse. According to National Institute on Drug Abuse (NIDA), marijuna is a drug, and I think it's a synonym of cannabis. So drug abuse and cannabis consumption are not two different things. We can also rephrase the sentence without using 'in general'.
Why drug abuse, cannabis consumtion in particular, is dangerous for your health.