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Reply to "Zero conditional"

Yale Wale posted:

I was planning a lesson on conditional sentences and I came across a site that talked about types of conditional statement one of which is 'zero conditional.'

Hi, Yale Wale,

It would be good if you could share a link to the information you found at that website, so that we can see the overall quality of information at that site.

Yale Wale posted:

It says this kind of conditional statement is used to express general truths or scientific facts in which one thing causes another.

Yes, that's right, but they don't have to be lofty general truths or technical scientific facts. In zero conditionals, the "if" can generally be replaced by "when" or "whenever." And, yes, both clauses use the simple present:

  • If/When(ever) it rains, it pours.
  • If/When(ever) water is heated to X degrees, it boils.
  • If/When(ever) he doesn't get enough sleep, he is grouchy.
Yale Wale posted:

It also says that the verbs in both the conditional clause and the main clause in the statement should be simple present tense, e.g.

1. If people smoke cigarettes, their health suffers. 

Then, it says it is wrong to use the future 'will' in such a statement, e.g. 

2. If people smoke cigarettes, their health will suffer. (Considered wrong)

I am confused by that rule that using 'will' makes the sentence incorrect.

Yes, "will suffer" doesn't work well there. But that's because the subject of the "if" clause is "people." The sentence is making a wide generalization that holds at all times, so the zero conditional is perfect. Note that you can substitute "when" or "whenever" for "If":  "When(ever) people smoke cigarettes, their health suffers."

That said, if (1) were changed so that it was particular to one person, then "will suffer" would be fine. Indeed, it would be the most natural choice, because the point of the sentence would then be to make a prediction about what would happen to the person if he or she smoked.

  • If he smokes cigarettes, his health will suffer.
Yale Wale posted:
I'd like to know if the rule is true and if there are standard grammar texts to support it.  

It is often possible to use the first conditional instead of the zero conditional, but the meaning changes from a generalization, or statement of regularity, to a prediction. In (1), a generalization was needed, because of the general subject of the "if"-clause. As we saw, if "he" were the subject, "will" would be OK.

Yale Wale posted:
Also, which of the following pair of examples is correct?

3a. If people go permanently blind, they will not see again.
3b. If people go permanently blind, they don't see again.
4a. If you leave yam tubers in the soil for days, they will rot.
4b. If you leave yam tubers in the soil for days, they rot.

The correct sentences are (3b), (4a), and (4b). The latter two differ in meaning.

Last edited by David, Moderator