II. The conditional mood

English conditional sentences can be divided into the two broad classes of factual/predictive and hypothetical (counterfactual), depending on the form of the verb in the condition (protasis).

In factual/predictive constructions the condition clause expresses a condition the truth of which is unverified. The verb in the condition clause is in the past tense (with a past tense interpretation) or in the present tense (with a present or future tense interpretation). The result clause can be in the past, present, or future. Generally, conditional sentences of this group are divided in two groups, the "zero conditional" and the potential or indicative conditional, often called "first conditional" or "conditional 1". This class includes universal statements (both clauses in the present, or both clauses in the past) and predictions [19].

1. The "zero" conditional is formed with both clauses in the present tense [12; 81]. This construction is similar across many languages. It is used to express a certainty, a universal statement, a law of science, etc.:

If you heat water to 100 degrees Celsius, it boils.

If you don't eat for a long time, you become hungry.

If the sea is stormy, the waves are high.

It is risky to eat prawns if they haven’t been kept at the right temperature.

We can use modal verbs in either clause, especially can and may [10; 121]:

Prawns can be risky to it if…

We use the zero conditional to talk about events or situations that can occur at any time, and often occur more than once, and their results:

If I eat oranges, I get red spots all over my skin.

We can use an imperative instead of a present tense in the result clause to give a general instruction [10; 121]:

If a chip pan sets alight, throw a fire blanket on it.

2. The potential or indicative conditional, often referred to as the "first conditional" or "conditional 1", is used more generally to express a hypothetical condition that is potentially true, but not yet verified. The conditional clause is in the present or past tense and the result can be in the past, present, or future [19].

Basic forms of Type 1 Conditionals [6; 282]:

'if-clause: main clause:

present tenses 'shall/will' future

condition to be satisfied likely outcome

be: If I am better tomorrow, I will get up

have. If I have a headache I will take an aspirin

simple present: If she finishes early she will go home

present progressive: if he is standing in the rain, he will catch cold

present perfect: If she has arrived at the station, she will be here soon

present perfect progressive If he has been travelling all night, he will need a rest

can, must. If I can afford it, I will buy it

Some examples with the condition clause in the past tense:

If she took that flight yesterday, she arrived at 10pm.

If she took that flight yesterday, she is somewhere in town today.

If she took that flight yesterday, we'll see her tomorrow.

A condition clause in the present tense refers to a future event, a current event which may be true or untrue, or an event which could be verified in the future. The result can be in the past, present, or future:

If it's raining here now, then it was raining on the West Coast this morning.

If it's raining now, then your laundry is getting wet.

If it's raining now, there will be mushrooms to pick next week.

If it rains this afternoon, then yesterday's weather forecast was wrong.

If it rains this afternoon, your garden party is doomed.

If it rains this afternoon, everybody will stay home.

If I become President, I'll lower taxes.

Certain modal auxiliary verbs (mainly will, may, might, and could) are not usually used in the condition clause in English:

If it will rain this afternoon, …

If it may have rained yesterday, …

There are exceptions, however, in which will is used exactly as in the first example, namely when the action in the if -clause takes place after that in the main clause [13; 249]:

The weather forecast says it's going to rain.) Well, if it will rain, we must take umbrellas. If aspirins will cure it, I'll take a couple tonight instead of this horrible medicine.

Other situations in which will can be used in an if- clause include when will is not being used as an auxiliary verb, in other words when it is being used modally to express willingness, persistence, refusal [10; 121] or a request [12; 84]:

If you'll just hold the door open for me a moment, I can take this table out to the kitchen.

If you will keep all the windows shut, of course you'll get headaches.

If you will excuse me, I think I will slip into something more comfortable.

If you want to make the request more polite you can use if … would:

If you would take your seats, ladies and gentlemen…

We may also use modal verbs in the main clause [6; 283]:

can (we are free to)

could (we would be able to)

may (it's possible)

If it's fine tomorrow, we might (it's possible) go out.

Should (it's advisable)

ought to (it's advisable)

must (it's necessary)

Progressive and perfect combinations with modals are possible:

If I hear from Tim, I may be leaving tonight If he is in New York he may not have got my letter yet

In hypothetical (counterfactual) constructions, the condition clause expresses a condition that is known to be false, or presented as unlikely. The result clause contains a conditional verb form consisting of would (or could, should, might) plus a main verb in the base form (infinitive without to) [19].

3. The contrary-to-fact present conditional, often referred to as the "second conditional" or "conditional 2", is used to refer to a current state or event that is known to be false or improbable [19]. Type 2 conditionals talk about imaginary situations in the if-clause and speculate about their imaginary consequences in the main clause. Though past tenses are used, the reference is not to the past time. (That is why this use of the past tense after if is often called 'the unreal past'.) By comparison, Type 1 conditionals talk about things which will possibly happen and consider their real consequences for the future. Depending on the attitude of the speaker, a Type 2 conditional can be used in place of a Type 1 to describe something that is reasonably possible. So:

If you went by train, you would get there earlier

If you didn't stay up so late every evening, you wouldn't feel so

sleepy in the morning mean the same, but are more 'tentative' than:

If you go by train, you will get there earlier

If you don't stay up so late every evening, you won't feel so sleepy

in the morning

However, Type 2 conditionals more often describe what is totally impossible:

If I had longer legs, I'd be able to run faster

In Type 2 conditionals the past subjunctive (or in colloquial English, simply the past tense) in the if-clause and “would” + non-perfect infinitive in the main clause must be used [9; 142]:

If she were [colloq. was] at work today, she would know how to deal with this client.

If I were [colloq. was] the king, I could have you thrown in the dungeon.

If I were you, I would accept their offer.

The same structure can be used to refer to a future state or event:

If I won the lottery, I would buy a car.

If he said that to me, I would run away.

Basic forms of Type 2 conditionals [6; 285]:

'if'-clause: main clause:

past tense 'would/should' condition to be satisfied likely outcome

be: If I were taller, I would become a policeman

have. If he had any money, he'd leave home

other verbs: If you took a taxi, you'd get there quicker

could: If you could see me now, you'd laugh your head off

In conditional sentences we may use the expression If it were not for/Were it not for that explains why something has or hasn't happened. In this case one situation is dependant on another situation or on a person [6; 286]. When we talk about the past we use If it hadn’t been for … [12; 88]:

If it weren't for your help, I would still be homeless.

If it hadn’t been for my parents, I would never have gone to university.

In formal contexts, If it were not for can be expressed as Were it not for, with the negative in full (Not * Weren't it*): Were it not for your help, I would still be homeless.

If it were not for and Were it not for are often followed by the fact that: Were it not for the fact that you helped me, I would be homeless

We can also use Had it not been for…:

Had it not been for my parents, I would have never gone to university.

We often use but for + noun with a similar meaning [12; 88]:

But for Jim’s support, I wouldn’t have got the job.(= If it hadn’t been for Jim…)

In unreal conditionals we use if…were + to-infinitive to talk about imaginary future situations [10; 122]:

If the technology were to become available, we would be able to expand the business.

If he were to have a chance of success, he would need to move to London.

However, notice that we can’t use this pattern with many verbs that describe a state, including know, like, remember, understand:

If I knew they were honest, I’d gladly lend them the money.

We sometimes use this pattern to make a suggestion sound more polite:

If you were to move over, we could all sit on the sofa.

In the main clause of Conditional 2 sentences modal verbs may be used [6; 286]:

'If'-clause: past tense main clause: modal

condition to be satisfied likely outcome

If he knew the facts, he could tell us what to do

If he could get the facts, might

Another modal can replace would in Type 2 conditionals, e.g. when we feel the imaginary consequences are less likely, or when we are referring to ability, possibility, etc.:

condition to be satisfied likely outcome

If he were here he could help us. (ability)

If he were here he might help us. (possibility)

If he failed, he ought to/should try again. (duty)

Progressive and perfect combinations with modals are possible:

If she were here now she could be helping us. If he were in New York, he could have met my sister. If they were in the army they would have been fighting in the jungle most of the time.

4. The contrary-to-fact past conditional (sometime referred to as the "third" conditional, conditional 3) is used to refer to contrary-to-fact past events [19]. Type 3 conditionals assume something purely imaginary in the if-clause and consider the imagined consequences in the main clause. In this respect they are like Type 2. However Type 3 conditionals refer to consequences which did not and could not (now) ever happen because they refer to something that didn’t happen in the past. They are hypothetical conditions [6; 288]. The past perfect is used in the condition clause and “would” + perfect infinitive is used in the main clause [5; 25]:

If I had worked harder at school, I d have got a better job If I hadn't been wearing a raincoat, I would have got wet

If you had called me, I would have come.

If it had rained, we would have stayed at home.

We use Type 3 conditionals to speculate about a range of possibilities from what might have been reasonably expected to what would have been completely impossible.

Basic forms of Type 3 conditionals [6; 287]:

'if'-clause: main clause:

past perfect 'would have/should have'