118. Problems with Conditional “if”


If copper is heated, it expands

If copper is heated, it expands

Writing conditional sentences with “if” can cause a variety of common language errors



Most grammar descriptions have plenty to say about conditional if, but they often simply present its associated subtle meaning differences and rather complicated word combinations without highlighting many of the common errors that these can give to writers whose mother tongue is not English. In this post I wish to focus wholly on various errors that the use of conditional if can cause, and to offer information that might help them to be avoided.

To facilitate the analysis of the problems, it will be useful to appreciate the main properties of if sentences. Consider this example:

(a) If copper is heated, it expands.

The underlined parts are verbs. Two are usually needed with if, reflecting its status as a conjunction (see 25. Conjunction Positioning). The verb with if can come first, as here, or second, with if in the middle of the sentence. A starting if may have a following then (see 64. Double Conjunctions).

The action or state of the if verb is a “condition” for the action or state of the other verb. This means it has two properties. Firstly, it is needed before the action or state of the other verb can happen or exist – this other verb expresses a consequence of the if verb. Secondly, the action or state of the if verb is hypothetical – its occurrence is not definite like many of the causes in the post 32. Expressing Consequences. More on this difference is in the post 61. “Since” versus “Because”.

The tenses of the two verbs can be changed in a variety of ways in order to express a variety of meanings. In most cases, both of the verbs have to be changed together. I do not propose to list all of the possibilities because they are easily found in mainstream grammar descriptions. However, as an example, expands above can be changed to will expand, making the sentence more a prediction than a rule (see 147. Types of Future Meaning). Unusually, this particular change does not require the other verb to be changed.



1. Similarity of “if” to “in case”

This problem is further considered in the post 100. What is a Grammar Error?. Compare the following:

(b) Paracetamol may be administered if the patient becomes feverish.

(c) No visitors are allowed in case the virus is transmitted to them.

In (b), the underlined hypothetical event (after if) happens before the other event in the sentence, whereas in (c) (after in case) it happens after. This means if highlights a cause, while in case highlights a result. What they have in common is that the cause/result may not happen at all. In case means “to prepare for the possibility that …”.


2. Similarity of “if” to “whether”

If can be used, with different meaning, in indirect questions. In such cases it is usually replaceable by whether (see 57. Indirect Questions in Formal Writing). More confusing, however, is the fact that whether is also possible in conditional sentences, but with a different meaning from if (see 99. When to Use “whether … or …”). Consider the following:

(d) Drug-smuggling will be a problem whether supply is controlled or demand.

(e) Demand will fall if prices rise or substitutes appear.

Sentence (d) illustrates what I call the “condition-denying” use of whether. It says that the two following events are not conditions for the main event: that event will happen in all circumstances. In (e), however, the two events mentioned after if are both conditions. If … or … seems to be needed instead of whether … or … when the mentioned conditions are not the only possible ones. In the case of (e), a possible unmentioned condition might be fashions change.


3. Similarity of “if” to “when”

Some languages have a single word for both if and when, causing their speakers to use when excessively in English. This word lacks the hypothetical part of the meaning of if – the possibility of the non-existence of the event or state mentioned after it. Consider sentence (b) again. The presence of if suggests that the patient may never become feverish at all. Replace it with when, however, and future feverishness becomes expected. The same difference exists in all of the other if sentences above.

However, some sentences are perhaps less clear-cut. One type is where the two linked events are both in the past, like this:

(f) The children received a prize if they won their race.

This sentence does not suggest that the event after if may not have happened at all: some children certainly did win their races. However, some hypotheticality remains, since there is no certainty that everyone won, as there is with the use of when.

Sentence (a) above, which states a general rule, also seems a little like this, if suggesting a slightly less likely occurrence than when. However, for practical purposes the two words in general rules like (a) seem interchangeable.


4. Similarity of “even if” to “even though”

Adding even conveys surprise. The choice between if and though is similar to that between if and when, if being more hypothetical. Consider this:

(g) The children received a prize even if they lost their race.

If again suggests that losing the race did not always occur – some children won. Replacing if with though, however, would mean all of the children lost their race. The sentence would then be what is technically called “concessive” rather than “conditional”, closer to the use of although than if.

A common error with even is to use it with if instead of though. Consider this further example:

(h) Even … chickens have wings, they cannot fly.

Using if here would leave it undecided whether or not chickens have wings, whereas though would fully recognise their wings. Since most people know that chickens have wings, using if would be strange (though not impossible). In general, even if leaves unconfirmed the reality of the action or situation after it.


5. Use of “will” and “would” after “if”

Many learners of English incorrectly use will and would after if like this:

(i) *If the guests will arrive at 6, they will eat at 7.

(j) *If the earth would not be tilted, seasons would not exist.

In general, will and would cannot be used after if unless they mean “agree to” (if you would come this way, …) or “insist on” (if you will keep complaining, …). The correct verb forms in (i) and (j) are arrive and was not tilted.


6. Unusual Possibilities

One unusual possibility – an imperative verb instead of if – is considered in the Guinlist post 88. Exotic Grammar Structures 1. Another is an unusual meaning when if accompanies a past tense verb alongside a verb with would, like this:

(k) If their city was threatened, the Athenians would call an Assembly.

This combination usually expresses the so-called “unreal present”, referring to an unlikely action today. However, if the context made it clear that the past was the topic – ancient Athenians in (k) – then would would mean “used to”. Replacing if with when seems more possible in such cases: if just suggests a less frequent occurrence.

Finally, there is the use of were to after if (were is preferred even after singular nouns, as it is a rare unchanging form called a “subjunctive”). It refers to the future just like the present simple tense in sentences like (i), but it suggests unlikelihood of happening. It usually needs the other verb to have would instead of will:

(l) If the guests were to arrive at 6, they would eat at 7.

Speakers of other languages than English need to be especially careful in sentences like this to avoid saying would instead of were to.


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