Degrees of certainty

‘The only certainty is that nothing is certain. ‘Pliny The Elder

While explaining the use of different grammatical structures and words in English I have noticed that we often make choices according to scales of certainty. Many people may remember putting adverbs of frequency in order from 100% of the time – always, to 0% of the time – never.

Or love to hate - http://www.englishbanana.com/vocabulary/expressing-likes-and-dislikes.pdf.

But this theory can also be extended to modals, future forms and conditionals using degrees of certainty.

First modals. Say for example you see this scene –

You don’t know exactly what is happening but you can speculate using a scale of certainty where 100% sure is must and 100% sure that something is impossible is can’t. In this way we can say –

100% - He must be a thief

50/60% - He could be a car mechanic

30 / 40% - He may be a locksmith

10 / 20 % - He might be a policeman

-100% - He can’t be the owner of the car

In English we have four different ways to talk about the future depending on certainty.

Present simple – Very certain – for something out of our personal control that even if it is in the future for us happens every day or regularly at the same time (often timetables and schedules)

The bus leaves at 9pm.

Present continuous – Very certain – for a personal fixed plan for the future. We know all the details and we may write it in our diary.

On Monday I’m seeing the doctor at 11am.

Be going to – For an intention - quite certain but we don’t know all the details yet.

I’m going to have a holiday in the summer but I haven’t decided where yet.

Will – the least certain - for an idea or a prevision for the future.

I will go to India at some point in my life.

You will meet a tall handsome man.

This also works with conditionals. Zero conditional for something that is always true or always happens.  

Water boils if you heat it to 100%

First conditional for a real possibility for the future

If the weather is good tomorrow I will go out.

Second conditional for a very unlikely possibility for the present or future

If I won the lottery I would travel.

Third conditional for something in the past that is no longer possible but you would like to change, a regret or a criticism.

If you hadn’t driven so fast you wouldn’t have had an accident.

If I hadn’t studied French I would have studied History.

Even here it is possible to use a different verb instead of would. Would is sure, but you can also use could to express a possibility, or may or might for a smaller possibility.

So it looks like the English may agree more with American mathematician John Allen Paulos, when he says -

Uncertainty is the only certainty there is, and knowing how to live with insecurity is the only security.