This lesson will help you understand:
- the meaning of ‘deduce’ and ‘deduction’
- the meaning of ‘assume’ and ‘assumption’
- how to make assumptions and deductions in English
- the grammar of modals of deduction
- easy ways to remember the grammar and meaning
- how these modals are used and tested in IELTS
What do people ASSUME about you?
If you have a nice car, do people assume you’re very rich?
If you ride a bicycle to work, do people assume that you can’t afford a car?
When you assume something, you make a GUESS based on SOME evidence.
But it is still a GUESS, and your guess may be wrong.
One simple way to make a guess is to say ‘Maybe’.
‘She has a nice car. Maybe she’s very rich’.
A more advanced way to guess is to use a MODAL verb (must, may, could, might, can’t)
‘She MUST have a lot of money’ (about the Present)’.
‘She COULD have won the lottery’ (about the Past)’.
When we assume things, we look at the evidence and ‘deduce‘ (guess) information from that evidence.
We use a Modal of Deduction – must, may, could, might, can’t – to express how sure we are.
MODALS in IELTS
There is no Grammar test in IELTS (though you are given a score for Grammatical Range and Accuracy in Speaking and Reading).
So how can they check your understanding of this quite complex language point?
Very often in the Reading and Listening there are specific questions relating to the language of assumption/deduction.
This is because many of the texts are related to Academic Research. When you do research, you don’t always have all the evidence that you need to prove your theory.
So you have to make assumptions and guesses. And you have to tell your audience that you are NOT 100% sure. You are just guessing, based on some evidence.
Examples from the Listening Test
Listen to this extract from Part 4 of the Listening Test.
Now look at the tapescript:
‘The early farmers kept various animals, including cattle and sheep. There’s also evidence of pigs, but it is possible that these could have been descended from the native wild species.’
‘Now we know from modern farming that if the level of breeding stock falls below about 300 females, the future of the species locally is at risk.”
“So we must assume that from the beginnings of Neolithic farming the number of breeding sheep would have considerably exceeded 300, and the national cattle herd must have been of a similar size’.
How to remember modals of deduction?
Modals express how strong something is:
- I MUST go = a strong obligation
- It MUST be love/ She MUST be rich = a strong guess about NOW
- It MUST HAVE BEEN love/ She MUST HAVE WON the lottery = a strong guess about the PAST