Grammar

Zero Conditional - there's more to it than water boiling at 100°C

This is intended to be one of several posts where I take a look at conditionals from a rather different angle. Zero Conditional rarely gets more than a couple of lines in course books; I'm going to look at in rather more detail, and hopefully encourage you to think about its function, not simply its form.

1. Zero conditional - the basic principle

The most important thing to note is that Zero conditionals are about conditions which are generally true, NOT about conditions on specific occasions.

Zero Conditionals - the classic rule

The classic rule often quoted for Zero conditional is

if + present simple, ........... present simple

Exercise 1 - Match the sentences to their functions below

1.	If water is heated to 100°C, it boils.
2.	If you are out of work you are entitled to unemployment benefit.
3.	If you click on the the blue button, the answers appear.
4.	If the weather's not too bad, I cycle to work.
5.	If the traffic light changes to amber, drivers have to stop.

a	facts, general truths
b	rules
c	scientific laws
d	habits and routines
e	instructions

2. Zero conditionals have the following characteristics:

They usually have the same tense in both condition clause and result clause.
We can usually replace if with when or whenever.
- If / When / Whenever I'm in town, I visit my aunt.
- If / When / Whenever the weather is fine, we go to the park.
- If / When / Whenever you buy two, you get an extra one free.
When we use the word you in Zero Conditional, it often refers to people in general, not somebody in particular.
- What do you do if you have some free time? (you = you)
- What do you need if you want to make a model airplane? (you = people in general)
We can sometimes use unless instead of if not
- Unless it's raining, I usually go for a walk in the forest on Saturdays.
- People can't fish in this river unless they have a permit.

3. Extending the classic rule

Although Zero conditionals usually use parallel structures (the same tense in each clause), many experts agree that we can also use modals and imperatives in the result clause of a Zero conditional.

A. Zero Conditional with modals

Exercise 2 - Fill the gaps with the modals given

can · can't · musn't · must · ought · should · shouldn't

1.	If people want to be fit, they take daily exercise.
2.	He read unless he wears glasses.
3.	If you drive on the motorway, you have a full driving licence.
4.	You cross the road when the little man is red. Wait till he turns to green.
5.	You get sometimes get a discount if you have a loyalty card.
6.	If someone has high blood pressure, they drink coffee.
7.	You to see your doctor if you get severe headaches.

B. Zero conditional with imperatives

Remember that an imperative has the same form as 2nd person present simple.

Exercise 3 - Fill the gaps with the imperatives given

do · drive · make · place · remember · soak · take

1.	If you go to London, a trip on the London Eye.
2.	If you get stung by nettles, a dock leaf on the sting.
3.	If you go on holiday, to cancel the newspaper delivery.
4.	If you drink, don't .
5.	If you're ever in town, come and see us.
6.	If you take any medicine, always sure you read the instructions first.
7.	If you are cooking kidney beans, them overnight in cold water.

C. - Other present tenses in the if-clause

When you get to advanced level you are told that you can use present tenses other than Present simple in First conditionals. It's the same with Zero conditional:

If I'm driving, I always wear my driving glasses.
If I've eaten too much for lunch, I tend to feel sleepy in the afternoon.

D. Revised rule for Zero conditional

So we can now revise the classic rule to:

if + present tense, ........... present simple / modal / imperative

Remember that the most important thing is the general nature of the condition.

4. Real conditionals and Unreal conditionals

Another way of looking at conditionals is to divide them into two broad categories - those that use normal tenses, sometimes called Real conditionals, and those that use special tenses, sometimes called Unreal conditionals.

Zero and First conditionals are part of the first category - Real conditionals, that's to say that we use real time tenses with them. Note that there are many conditional structures in this category that don't fit into the Zero and First conditional patterns.

The main thing thing to remember here is that for present and future time we use a present tense in the if-clause and follow the normal rules of tense and modals in the result clause, and so:

Real conditionals include:

General conditions in the present (Zero conditional)
present ... present / modal / imperative
If it's raining, I usually take the bus.
Present or future probability (First conditional)
present ... will, going to / modal / imperative
If it's raining, we'll take the bus.
General conditions in the past (Zero in the past - see below)
Past simple / Past continuous ... past
If he was late for work, he took a taxi.
Past conditions (when we don't know if they've been fulfilled yet) with present or future result
Present perfect / Past simple / Past continuous ... will, going to / modal / imperative
If he managed to catch the early train, he should be here any minute.
Various constructions, where the result is dependent on the condition being fulfilled, but which don't quite fit the patterns of First conditional
If it stops raining, why don't we go for a walk?
Various other constructions, including false conditions, where the condition has already been fulfilled, and psuedo conditions where the result is not dependent on the condition being fulfilled. These often mix time references and tenses.
If you don't like seafood, you should have said.
If you're hungry, there's some ham and cheese in the fridge.

Unreal conditionals include:

Present or future condition when something is unlikely or hypothetical (Second conditional)
past ... would / modal / imperative
If it were't so far, we could walk.
Past condition with impossible result (Third conditional)
Past perfect ... would / could have
If he hadn't missed the train, he could have got there on time.
Mixed conditionals
If he hadn't missed the train, he would be here by now.
If he wasn't so slow, he would have caught the train.

I've already looked at what I call pseudo conditionals in another post (see below) and I hope to address the question of those constructions, where the result is dependent on the condition being fulfilled, but which don't fit the patterns of First conditional in another post soon.

There's a table below where I combine the two ideas: 0,1,2,3 and Real / Unreal in one overall view.

5. Zero or First Conditional?

Case study 1

Look at these two sentences, both of which are given as examples of Zero Conditional on ESL/EFL websites:

If he gets there before me, ask him to wait.
If I'm late for dinner, start eating without me.

Both of these sentences, with imperatives in the result clause, look to me as if they relate to specific occasions, in which case they are First Conditionals, not Zero. We have to think about the function, not only the form.

In fact, the website which gave the second answer says that this is an example of what to do in certain circumstances, not just on one specific occasion, in which case he's correct, this is a Zero Condition. These examples tell us two things:

Many teachers and experts accept an imperative in the result clause as an acceptable form in Zero Conditional.
In some circumstances a Zero Conditional can look exactly like a First Conditional
If I'm late for dinner (any day), start eating without me. (Zero Conditional)
If I'm late for dinner (tonight), start eating without me. (First Conditional)

Again we have to think of the function, not just the form.

Case study 2

In a couple of posts about the Passive I wrote a short exercise about the Taj Mahal, which included the following sentence:

If you are ever in Uttar Pradesh in northern India, you must visit the Taj Mahal

Again the structure is exactly the same whether it's a Zero or First conditional. I would say that it refers to a general condition, so is a Zero, but it's open to interpretation.

6. Zero in the Past?

There's a pair of sentences sometimes quoted on US grammar websites.

If he were sorry, he'd apologise.
If he was sorry, he apologised.

I think these are probably intended to show that you are 'supposed' to use the subjunctive were for hypothetical conditions and the indicative was for real conditions, but as I rarely use subjunctive were, I ignored that bit.

What bothered me was that second sentence: I couldn't make out what it meant. Finally I realised - it's not about a condition on a specific occasion, but about a general condition in the past. And this got me to thinking that it's really like a Zero conditional in the past.

We have, for example, parallel tenses, albeit in past simple. And remember that with Zero conditionals we can replace if with when or whenever, which is exactly what we can do here:

When(ever) he was sorry, he apologised.

This, I think, is rather easier to understand than the original version. I thought perhaps I'd invented a new category, but of course others had got there first, including Grammarring (linked to below). So my proposition is:

Let's have an additional sub-category - Zero in the past

if + past simple / past continuous, ........... past simple / used to / would (see below)

As well the famous - If he was sorry, he apologised - this would include sentences such as:

If he came to see us, he always brought a present for Charlie.
If we didn't feel like doing it, we didn't do it. It was as simple as that.
If she visited Paris, the first thing she used to do was go to the Louvre.
In Victorian times, if somebody didn't have a job, they often ended up in the poorhouse.
If he wasn't working at the weekend, he would go into the mountains.

If you thought that the last example looks like a Second conditional, you're absolutely right, the form is exactly the same, but here it's a general condition about his habits in the past. See the next section for an explanation.

To be honest, I don't think this type of sentence is very common, at least not with if. I'm pretty sure, when or whenever are more common.

7. Zero in the Past or Second Conditional?

Remember that we can use would instead of used to to talk about past habits. This means that Zero in the Past can sometimes look exactly the same as a Second conditional:

If she visited Paris, she would go to the Louvre.
Zero in the past - Every time she visited Paris in the past, she used to go to the Louvre. (visited = real past, would = past habit)
If she visited Paris, she would go to the Louvre.
2nd conditional - If at some time in the future she gets the opportunity to visit Paris (which she seems to think unlikely), she intends to visit the Louvre.(visited = unreal past, would = past of will)

In this type of sentence, the context will tell us which it is. And it illustrates again why I think it is just as important to think of the function as the form.

An overall view of conditionals

1. Real conditionals - these use normal tenses

True conditionals - the result is dependent on the condition being fulfilled

General conditions

Zero conditional
Zero in the past

Specific occasions

First conditional
'Quasi firsts' - Conditionals where the result is dependent on the condition being fulfilled , but which don't exactly meet the standard rules of First conditional, mixing time references for example, and including certain types of suggestions. I hope to look at these in a future post.

'Pseudo' conditionals - the result is not directly dependent on the condition

Various patterns of false and 'pseudo' conditionals using normal tenses in a variety of combinations. See my post

2. Unreal conditionals - these use special tenses

True conditionals - either hypothetical or impossible

These only apply to specific occasions

Open - hypothetical
Second conditional
Mixed 2/3
Closed - impossible
Third conditional
Mixed 3/2

3. Conditionals in narratives, reported speech, future in the past etc

These use a variety of forms, which often involve tense shifting

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