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, establishing it as a conjunction (see 174. Eight Things to Know about Conjunctions). The verb with if can come first, as here, or second, with if in the middle of the sentence (see 25. Conjunction Positioning). 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. For more on this difference, see 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 also illustrated 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 they both refer to the future, so 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 (for an exception, see 105. Questions with a “to” Verb). 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 (the German and Dutch word is actually spelled like when, causing overuse of this word in English). When 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 most of the other if sentences above.

However, some sentences are not so greatly affected by when replacing if. Most of these seem to be generalizations, whether timeless or about the past (see 179. Deeper Meanings of “if”). Sentence (a) above, for example, is a timeless generalization where saying when copper is heated…instead of if… seems to make almost no difference. Here is an example of a past-time generalization:

(f) Excursions were not allowed if/when the weather was bad.

Both if and when here imply that the weather was sometimes bad. The difference is perhaps that if emphasises the perspective of the people affected, for whom bad weather was a future event and hence less certain.


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 involves if with a past tense verb alongside another verb containing would. The usual meaning of this is that an “unreal” event or situation is being described, as in these examples:

(k) If Greenland had a warmer climate, more people would live there.

(l) If a meteor had not struck the earth, the dinosaurs would have survived.

In both of these, the words after if say something untrue: about a present situation in (k) (that Greenland has a warmer climate) and about a past one in (l) (that a meteor did not strike). These meanings are mainly differentiated by the tense of the verb after if: past simple and past perfect respectively.

The unusual meaning that can be expressed is a real event after if, like this:

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

In a past-time context, this means the city was sometimes threatened, and then an Assembly was called. The sentence is the same kind as (f) above, with if similar to when, merely expressing less inevitability of occurrence. This meaning is possible because would can have a “used to” meaning instead of the normal conditional one.

The same unusual meaning is also possible with a had verb after if:

(n) If it had rained, the wall would glisten.

Adding had to the first event here emphasises that it was completed before the second began (see 171. Aspects of the Past Perfect Tense). Note how the second event has would (= “used to”) rather than the would have that is typical of “unreal” past conditions.

A third unusual use is were to after if. It refers to the future like the present simple tense in sentences like (e), but it suggests unlikelihood of happening. The other verb needs would, not will. An example is:

(o) 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. Note also that were is always preferred to was, even after a singular noun. The reason is that this use of were is a rare unchanging form called a “subjunctive”. For another example of the subjunctive, see 88. Exotic Grammar Structures 1, #6.


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