We shall overcome ...

I learned this song quite soon after I started learning English almost half a century ago. It was a workers' song, it contained a promise, and it was part of the general narrative that when I would be an adult all the world would live in a socialist society. This means one of two things: Either the wise old men were wrong or adulthood is still to come.

Whatever it is, the use of the word shall was commonplace in my English lessons. My teachers, who had never seen an English-speaking country themselves, used it like they had heard it from their teachers, who had learned it another generation earlier. The rule they followed and taught was shall is used to form the future in first person singular and plural. So you would not say I will do it. but I shall do it. Today you can safely say that this is historically interesting but not relevant any longer. You use will to form the future with every person. Just don't get confused if you find shall in older texts in this older function.

shall modals

So what job is left for shall to do today?

'Almost none' would be an offhand answer. There used to be a time when shall was seen as the modal auxiliary expressing obligation (which is why you find it in the modals table) but in everyday English it will be hard to find. If you still find a lot of shall in your English language environment, chances are good that you are either active in big business or actively in trouble, because shall only survives in legal English (i.e. the language of justice, laws and contracts). Here it is very frequent and means nearly the same like must or have to (but sounds much friendlier).

The bottom line is...

...that you don't have to use shall at all if you don't want to. To express obligation you will have to use an analogue. Be to is a good choice here, but others like be expected to or be supposed to are more frequent in spoken language.

"Sorry, I didn't do my homework. I had to go to football training." You hope this sentence would be enough, but of course it isn't. "You are expected to know that your duties come before leisure" is your teacher's answer. "Yes" you counter, "but my coach told me I was supposed to play in the finals and so I am to use every free minute to prepare for that." This argument should finish him off, you think. Your neighbour grins at you and quotes the Bible, whispering "Thou shalt not bear false witness". Well, he is on the same team. He knows.

We should talk about should

While shall is dying a slow death (may it rest in peace), should enjoys a healthy and busy life in all sorts of communicative backgrounds. There is one little difference to what you read about would: Sould usually expresses some advice or an assumption. In contrast to would, however, should should not be used to express past tense.

Here are some examples:

I should have listened to his advice

It's true that we live and learn - but sometimes we learn too late and make mistakes. This is especially embarrassing if we have been warned earlier. To express your regret, you need to repeat the advice in a way that refers to the past. You do that by leaving should untouched and shifting the full verb into present perfect. The result is ... well, you read the result in the heading of this paragraph.

One more example:

You shouldn't have said this to me.

It works the same way with should in assumptions:

He should have been at home by then.

Here you can go back to the modals table.