Probably one of the most widespread mistakes among non-native speakers is the use of the Second Conditional, the one where we express a rather hypothetical or unlikely event as opposed to the First Conditional where the idea expressed by the speaker is probable.
Let’s briefly look at the grammatical structure of both. Conditional sentences always have 2 phrases, the if-clause and a main clause. In case of the 1st conditional, the if-clause is usually in present tense and the main clause contains a modal auxiliary, will being the most common:
If we get the bus, we will arrive earlier.
If it rains tomorrow, we won’t be able to go fishing.
This is very straightforward and not many people get it wrong. Problems arise in the grammar of the Second Conditional. In my experience people know the difference in use, but they tend to make a serious grammatical error:
* If I would have a lot of money, I would buy a helicopter.
Can you guess what’s wrong with this sentence? The problem is that in the if-clause we have would and English grammar prohibits that in real conditionals. So, how would we correct the sentence? By using the past tense of the verb:
If I had a lot of money, I would buy a helicopter.
The main clause does get the would or any other modal auxiliary whereas in the if-clause we need to use past or what was historically the subjunctive. Mostly the past tense and the subjunctive coincide, except for the verb be in first and third person singular: If I were, If she were, etc.
Ok, so never using would in the if-clause is a good rule of thumb, but there are some exceptions when you can use it:
- Polite requests. When you ask someone for something and you want to be really formal, you can freely deviate from this rule:
If you would take your seats, I would be able to start the presentation.
This is not really a conditional but a polite request (you want them to sit down).
2. Result. If the if-clause is the result of the main clause:
You can open the window if it will help you to sleep.
Helping you to sleep is the result of opening the window.
3. Disapproval. If we want to show that we disapprove of something:
I can’t explain if you won’t listen to me.
I hope you are going to use it properly from now to make your speech more elegant. Because if I had a penny for every time I heard somebody use it badly, I would be a rich man. And if I were a rich man, I would…
Sources and further reading:
Advanced Grammar in Use (Unit 84)