John did not come. However, this is not necessarily so. It would be possible to continue:
. . . and since John came, Mary must have left.
Formally, this conditional is unreal. For unreality is again expressed by tense marking, but in a more complex way. Since it is both past and unreal, tense needs to be marked twice: a 'past-past' form is required. In the protasis the form had come is used. This is found elsewhere in English to express past-past
(see 3 . 3 . 3 ) : had come is the 'past-past' of past came, present
come. In the apodosis there is again double marking, once with
would, and once with have. This follows from the fact that there can be no form such as *had will, because of the rules about the modal paradigm, but the marking of the (second) tense with a following have is exactly like that of needn't have (6.5 .3) , ought to have (6.7. 1 ) and daren't have (6.8) .
Predictive conditionals in the past are generally unreal (but see
7.4. 2) . There is a simple reason for this. The past, unlike the future, is known and any such conditional in the past must at least suspend judgment on the facts, or indicate some degree of doubt or disbelief. There are then three important types, all predictive. A further set of examples is:
If it rains, the match will be cancelled.
If it rained, the match would be cancelled.
If it had rained, the match would have been cancelled.
(real)
(unreal)
(unreal) Apart from these rules concerning tense marking for unreality, there are two other rules for conditionals. First, for conditionals referring to the future, WILL (or SHALL) is not used in the protasis. This is true of both real and unreal conditionals. It is not possible in English to say (except with a quite different meaning - see 7 .4.3):
IIf John will come, Mary will leave.
IIf John would come, Mary would leave.
The plain future conditionals require comes and came here.
Secondly, the apodosis in unreal conditions must contain a modal verb (in its past tense form). Thus the first of each pair below may be unreal, but the second must be real:
If John came, Mary would leave.
If John came, Mary left.
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If John had come, Mary would have left.
If John had come, Mary had left.
The second of each pair have to be interpreted as 'If John came, it follows that Mary left', and 'If John had come, it follows that Mary had left'. The past tense form of the apodosis alone cannot indicate unreality, but only time. (For the interpretation of these see 7.4.2. )
The absolute need for a modal in the apodosis is shown by considering:
If John comes, Mary is going to leave.
If John came, Mary was going to leave.
Here BE GOING TO is used instead of will; this is less common but possible. The first example can still be regarded as predictive and is a real conditional, but the second cannot be treated as its unreal counterpart. It must be treated as real and past, in contrast with a sentence containing would which would be unreal and future.
Although WILL is the modal most associated with conditionals other modals can be used. But they involve both semantic and formal problems and will be discussed in detail later (7.4.3).
Finally in this section , it is to be noted that there are con
ditionals in which the condition is not explicitly stated. The remaining sentence is, then, essentially an apodosis with no protasis. The rules are the same. The conditional nature of will has already been discussed, but there are also plenty of examples of (unreal) would and would have. There are various possibilities,
eg:
[i] The condition is implicit in the linguistic context (but not marked with if) :
You would be unwise to do that.
No one would want to publish a book as difficult as that.
[ii] The condition is simply contained in a pronoun such as it
or that meaning 'if it were so' , 'if you did that' , etc:
That wouldn 't be sensible.
It would be very nice.
[iii] There is an implied 'if I were you' (giving advice):
I shouldn 't be in too much of a hurry.
I wouldn 't risk it.
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[iv] The implicit condition is vague, but simply relates to a possible or different state of affairs:
I would encourage people not to smoke.
You wouldn't want to harm him, would you?
7.4.2 Other types
The conclusion of the last section was that all conditional sentences are basically the same, but that there are three common types that generally indicate some kind of causal connection between two possible events. But there are other possibilities.
[i] If seems to have the sense of 'whenever' in:
If John comes, Mary leaves.
If it rained, I went by car.
This interpretation is possible, of course, only because the simple forms of the verb are treated as habitual; the 'when
ever' sense is not, then, strictly a feature of if, but of the verb.
These can be seen, however, as real conditionals with a causal implication, and, if so, provide examples of real conditionals in the past. But they are restricted to habitual actions, and, provided there is no modal in the apodosis, distinct from unreal future conditionals.
[ii] There is no causal connection in:
If John came, Mary left.
If John comes tomorrow, Mary left yesterday.
Indeed, a causal connection is impossible in the second example, because the events referred to in the protasis are subsequent to those referred to in the apodosis. In both cases the interpretation is in terms of the speaker's infer
ence. He infers that the one event took place because of the evidence of the other. But although there can be no causal connection between the events, the two propositions are conditionally linked, the truth of one implying the truth of the other.
Within this type of conditional may be included such sentences as:
If he's Prime Minister, I'm a Dutchman.
The conditional relation between the two propositions here is wholly in accordance with the rules of formal logic!
Sentences of this type are sometimes described as 'hypo
theticals', rather than conditionals (eg. Dudman 1 983:3ff).
But they are not truly very different. The absence of a causal connection and, therefore, the implication of infer
ence is a result of the time relation between the two prop
ositions. The general pattern of 'If p then q' still holds. In fact drawing a distinction between hypotheticals and conditionals creates a problem concerning the status of conditionals involving simultaneity of the propositions as in:
If John's here, Mary is too.
If John 's working, he's happy.
Because these propositions do not refer to momentary actions, but to continuous states, these can be seen in terms of cause and effect, or equally in terms of inference. It is, therefore, open to debate whether they are 'hypotheticals', or 'true conditionals' (and whether the true conditionals can be present as well as past or future).
There are unreal counterparts to these , but the rule that a modal must be present applies, and would has to be
supplied:
If John were here, Mary would b e too.
If John was working, he would be happy .
These, however, are indistinguishable in form from future conditions. The distinction of hypothetical and conditional seems then to create more problems than it solves.
[iii] There is some kind of ellipsis ('something left out') in sentences such as:
If you want to know, I haven't seen him.
If you're going out, it's raining.
These have to be interpreted as something like:
If you want to know, I'll tell you that I haven 't seen him.
If you 're going out, you ought to know that it's raining.
In other words, it is the giving of the information or the relevance of the information, not the proposition, that is
dependent on the proposition in the protasis.
This is not a phenomenon confined to conditionals. There is something similar in:
He works hard, because he wants to be rich .
He works hard, because he's at the office every morning at nine.
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