Learn English – When to use “should do something” & when to use “be supposed to do something”

subjunctivesword-choice

be supposed to do something:

used to say what someone should or should not do, especially because
of rules or what someone in authority has said

We’re supposed to check out of the hotel by 11 o'clock.

It seems that native speakers prefer to use "be supposed to do" over "should do".

Let see this scenarios in a movie. A man is going to leave his wife for another woman. The wife said "What am I supposed to do to raise my children?"

Compared to the sentence "What should I do to raise my children?"

The difference is a bit subtle.

So, When to use "should do something" & when to use "be supposed to do something"?

Best Answer

Frequently, supposed to {do something} is used when telling a person the proper way to do something. Modal should isn't as authoritative as supposed to.

You're supposed to turn the dial counter-clockwise.

You should turn the dial counter-clockwise.

The first sentence expresses the idea "I know how this thing works (possibly because I've read the instructions carefully or have done it before myself or have seen it done). When turning the dial, turn it counter-clockwise."

The second sentence expresses the idea "My advice would be to turn it counter-clockwise". That idea might be expressed with greater or lesser force, depending on the tone used. But it's not as clear with should where the authority resides, in the speaker's opinion, or in fact, externally.

We can also use supposed to to refer to an obligation or responsibility imposed on us by an authority, or even by our own conscience or superego, whatever you might like to call it.

I can't play baseball today. I'm supposed to pick up my little brother after school.

We couldn't really say the following:

I can't play baseball today. I should pick up my little brother after school.

because the latter sentence might be understood to mean that you're contemplating possibly not picking up your little brother. should doesn't express obligation and necessity, but merely what is advisable.

Your example "How am I supposed to raise my children!?" could be paraphrased:

I understand that I must raise my children, that this is my responsibility. How will I ever live up to that obligation, under the present circumstances?

The tacit reference is to an obligation or necessity, an unavoidable responsibility.

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