Saying that “if” introduces a condition is not a precise enough description of its meaning
THE COMPLEXITY OF “IF”
Most people who have studied English grammar know that if is a tricky word. The problem is not just its differing meanings in conditional statements and indirect questions, which mark it out as “multi-use” (see 3. Multi-Use Words). Even if we just concentrate on the conditional use, we find that it has to be distinguished from other “conditional” conjunctions like on condition that, provided that and assuming that, and that it is associated with some quite complicated verb tense rules (see 118. Problems with Conditional “if”).
The actual meaning of conditional if is also troublesome. As with other conjunctions, it is best expressed as a relation between two parts of the same sentence (see 174. Eight Things to Know about Conjunctions). In most coursebooks, not much more is said about this relation than that the if part names “a condition” for the event or state expressed by the other part.
The problem with this is that the word “condition” is vague: it means different things in different sentences – just as words attempting to sum up the meaning of other conjunctions do (see, for example, the discussion of but in 20. Problem Connectors, #3). Even the alternative term “hypothetical cause”, which I use in the above-mentioned post on if, has similar vagueness.
I feel that this problem has to be addressed because proper understanding might assist the learning of the different types of conditional sentence that feature in most standard English courses. It might also help to prevent grammatical errors. I do not know for sure whether all of the different meanings of conditional if are possessed by the equivalent word in all languages, but I would be surprised if they were. And if they are not, errors become likely.
Below are my ideas on subclasses of “conditions” that I believe can be expressed by if in English. A key factor is the likelihood of the condition being met. This is not particularly linked to the tense of conditional verbs.
No conditions are certain to be met – the uncertainty of their occurrence is indeed fundamental: if they were certain to occur they would not be conditions at all and would have to be linked to their outcomes by conjunctions like when or since rather than if. However, some conditions are more certain to be met than others.
The kind of condition that seems the most likely to be met is particularly common in chains of logical reasoning. Consider these:
(a) If x equals 3, y equals 6.
(b) If the accused was elsewhere, she did not commit the crime.
In some contexts, conditions like this are a consequence of preceding logical deduction, and hence are very likely to be true. Indeed, I would go so far as to say that in these circumstances the speaker is certain of their truth and is using if instead of since merely in order to hedge – avoid making a dangerously categorical statement (see 95. Hedging 1 and 61. “Since” versus “Because”). Thus, if here means “if it is true that”, and is easily replaced by assuming or even since.
This kind of condition may be illustrated as follows:
(c) If the liquid turns red, the test will be positive.
(d) If payment is early, a discount will be given.
(e) If the weather was/had been bad, profits fell.
(f) If water is heated to 100C, it boils.
These all contain a condition whose fulfilment cannot be considered particularly likely or unlikely: the underlined events will sometimes happen, sometimes not.
There are a number of interesting observations that can be made. Firstly, notice the variability of the time references. Past, present and future times are all possible. If the if verb is past, the other verb will normally lack would, though this word can be used with the meaning of “used to” (see 118. Problems with Conditional “if”, #6). For advice on choosing between past simple was in (e) and past perfect had been, see 171. Aspects of the Past Perfect Tense.
Secondly, the sentences illustrate a difference between general and specific open conditions. The condition in (c) could be either: perhaps describing the behaviour of the liquid at all times when the procedure in question is performed, perhaps describing it in a single performance at a single time. The condition in (d) too could be referring generally to payment at any time, or specifically to particular payment at a particular time. The condition in (e), on the other hand, is only general: it refers to numerous past events rather than just one. Sentence (f) also has a general condition, referring to all water at all times.
Knowing the generality of an open condition is important for knowing whether if can be replaced by when. The rule is simple enough: replacement is possible with general conditions but not specific ones. Thus, when could replace if in all of the above sentences, but (c) and (d) could then only be understood as generalizations.
This rule might be explained as follows. General conditional sentences refer to multiple occurrences of the condition, while specific-time sentences refer to single ones. With multiple occurrences, when is possible as well as if because the certainty of occurrence that when suggests can still be present alongside the uncertainty of occurrence that if implies: some conditions will be met and some will not. With single occurrences, on the other hand, the certainty of when cannot exist alongside the uncertainty of if: you have to choose one or the other. Thus when in the non-general interpretation of (c) would say that the red colour must appear, while if would say that its appearance was uncertain.
A third observation concerning the above sentences is that in (c) the test will be positive is a deduction – a thought, not an event, resulting from the fulfilment of the condition – just as it is in (a) and (b). Open conditions with this kind of consequence are quite often associated with investigations, especially laboratory tests.
Fourthly, some of the four conditions can begin with provided (that) or similar (providing that, on condition that, as long as) instead of if. This seems particularly true of (d), but possible in (c) too. My grammar books say provided expresses a meaning of if that does not exist in all conditional sentences: the suggestion that no other condition is possible for the mentioned consequence. In other words, it means “if and only if”. However, I think more is often involved than this.
I would suggest that a frequent cause of if meaning “provided” before open conditions is the making of a promise. This is certainly happening in (d), and could be understood in (c) too. Promises involve futures considered to be desirable (see 147. Types of Future Meaning, #2). In sentence (d), the desirable future is a discount; in (c) the possibly desirable one is a red colour. In sentence (e), on the other hand, the outcome profits fell is undesirable, and no promise can be understood (its desirable opposite profits rose would also not be a promise, because of its past nature).
In (f) the outcome it boils is neutral. Here too, provided could replace if, but without suggesting a promise. This is perhaps the main kind of sentence where if just means “if and only if”. Perhaps if is preferred to provided when this meaning does not need to be emphasised.
Finally, it is to be noted that promising is not the only special effect that can achieved by using an open condition with a future outcome. Others include offering, threatening, warning and suggesting. However, none of them seems to allow any synonym of if. A typical warning sentence might be:
(g) The device can overheat if (it is) left running too long.
UNLIKELY AND UNFULFILLED CONDITIONS
Conditions can express unlikely futures with were to partnered by would in the main verb, like this:
(h) If aliens were to visit Earth, great changes would occur.
Saying this in the more common future-referring way, with visit…will occur, would make an alien visit sound much more likely (though still not “likely”). A sometimes-found alternative to were to that does not change its meaning is the simple past tense of the verb (visited above).
Conditions labelled “unfulfilled” rather than “unlikely” express events or situations that are untrue or unreal either at the present moment (“Type 2” conditions in many English coursebooks) or in the past (“Type 3”). I do not wish here to repeat the details about them that can be easily found in coursebooks. Consider, though, this modification of sentence (b):
(i) If the accused had been elsewhere, she would not have committed the crime.
Unlike (b), this says the accused was not elsewhere: the condition is untrue and is hence “unfulfilled”.
The point I wish to make here is that the meaning of if in unfulfilled conditions is very hard to specify with more than the words “unfulfilled condition”. If seems not to be replaceable by any synonym; none of those that apply elsewhere – assuming, since, when, provided – is an alternative.