Rational vs Rationale: Which One Do You Need?
Rational means reasonable. A rationale is the reasoning behind something.
A rational decision. The rationale for it.
The test that settles it
The one with the final e is a thing. If you can put a or the in front, it is rationale.
“a ___ explanation” → describing it, so rational.
“the ___ behind the change” → a thing, so rationale.
Rational: reasonable
An adjective meaning based on reason rather than emotion, or capable of reasoning. Stressed on the first syllable.
A rational response to the data.
She stayed rational throughout.
Rational self-interest.
Swap in sensible. If it works, rational.
Rationale: the reasoning
A noun for the set of reasons that justify a decision or belief. Four syllables, stressed on the third: rash-uh-NAHL.
The rationale was never published.
What is the rationale for the cut?
A clear rationale for the change.
Swap in reasoning. If it works, rationale.
Side by side
| Rational | Rationale |
|---|---|
| Reasonable | The reasoning |
| Adjective | Noun |
| RASH-uh-nal | rash-uh-NAHL |
| A rational plan | The rationale for it |
The exceptions
To rationalise can mean to make something more efficient, or to invent a comfortable explanation for something you did anyway. The second sense is usually critical.
A rational number is one expressible as a fraction. The link is ratio, not reasonableness.
Where people get it wrong
| Incorrect | Correct | Why |
|---|---|---|
| a rationale decision | a rational decision | Describing it. |
| What is the rational for this? | What is the rationale for this? | A thing. |
| He is not being rationale. | He is not being rational. | Reasonable. |
| the rational behind the policy | the rationale behind the policy | The means a noun. |
Practice — choose the right word, then check yourself.
- She gave a clear ___ for the decision.
- It was the only ___ option.
- Try to stay ___ about this.
- The ___ was set out in the appendix.
- A ___ number can be written as a fraction.
Show the answers
1. rationale 2. rational 3. rational 4. rationale 5. rational
Frequently asked
Which is the common slip?
Writing rational where a noun is needed: the rational for the change. The the gives it away.
Do they share a root?
Yes — Latin ratio, meaning reckoning or reason. So does ratio itself.
More words people confuse
