Conditionals: If, Would, and the Sentence That Describes an Impossible Past
Conditional sentences pair a condition with a result. English has four standard patterns, and they differ in how likely the condition is.
Zero: things that are always true
If you heat water to 100°C, it boils.
Present tense in both halves. Used for facts and rules, where if means whenever.
First: a real future possibility
If it rains, we will cancel.
Present tense after if, will in the result. Something that might genuinely happen.
The rule that catches learners: never will after if. If it will rain is wrong — English marks the future once, in the result clause.
Second: unlikely or imaginary
If I won the lottery, I would buy a house.
Past tense after if, would in the result. The past tense here is not about time — it marks distance from reality. English uses pastness to signal unreality, which is why the sentence is about the future while looking like the past.
This is where were appears for all subjects: If I were you, not if I was you. That is the subjunctive, and it survives almost nowhere else in modern English. If I was is widely used and widely marked as informal.
Third: the past that did not happen
If I had studied, I would have passed.
Past perfect after if, would have in the result. This describes an alternative past — something that did not occur, and its consequence, which also did not occur.
It carries regret, blame or relief almost automatically, which is why it appears constantly in arguments and apologies. If you had told me, I would have come.
The most common error in English: If I would have studied. Never would in the if clause. The clause takes had.
Mixed conditionals
The halves can come from different patterns when the timing calls for it:
- If I had studied medicine, I would be a doctor now. Past condition, present result.
- If I were more organised, I would have finished already. Present condition, past result.
Two mechanical points
Comma placement. When the if clause comes first, use a comma. When it comes second, do not. If it rains, we will cancel. / We will cancel if it rains.
Unless. It means if not, so do not double the negative: Unless you hurry, we will be late — not unless you don’t hurry.
Checked against Merriam-Webster, the Chicago Manual of Style and the AP Stylebook. Spotted an error? Tell us — see our editorial policy.
