English makes a very clear distinction between "should" and "must", with should expressing a softer obligation (which could be as soft as "it would be in your best interests" to do a thing), whereas, the word must expresses a "have to". Both should and must are translated by the Esperanto word "devi"

Can I show this same difference of degree by using devi in the conditional tense?

Examples:
You must pay now or you will be sued.
Vi devas pagi nun, aŭ vi estos procesita.

You really should ask your doctor to check that at your next appointment.
Vere, vi devus peti ke via kuracisto kontrolu tion en via sekvonta enoficigo.

Am I on the right track, guys? Correct my translations if they are incorrect, please.
Thanks in advance for your help and advice.

Polaris:English makes a very clear distinction between "should" and "must", with should expressing a softer obligation (which could be as soft as "it would be in your best interests" to do a thing), whereas, the word must expresses a "have to". Both should and must are translated by the Esperanto word "devi"
Can I show this same difference of degree by using devi in the conditional tense?

That's one way. Maybe consider the affixes "-ind-" and "-end-".

So your examples below are ok, just some suggestions:

Examples:
You must pay now or you will be sued.
Vi devas pagi nun, aŭ vi estos procesita.

Use "nepre" if you think "devi" alone is too weak: Vi nepre devas pagi nun ...

You really should ask your doctor to check that at your next appointment.
Vere, vi devus peti ke via kuracisto kontrolu tion en via sekvonta enoficigo.

You can use the imperative form: Vere vi petu ke via kuracisto ...

Johannes

johmue:

Polaris:English makes a very clear distinction between "should" and "must", with should expressing a softer obligation (which could be as soft as "it would be in your best interests" to do a thing), whereas, the word must expresses a "have to". Both should and must are translated by the Esperanto word "devi"
Can I show this same difference of degree by using devi in the conditional tense?

That's one way. Maybe consider the affixes "-ind-" and "-end-".

So your examples below are ok, just some suggestions:

Examples:
You must pay now or you will be sued.
Vi devas pagi nun, aŭ vi estos procesita.

Use "nepre" if you think "devi" alone is too weak: Vi nepre devas pagi nun ...

You really should ask your doctor to check that at your next appointment.
Vere, vi devus peti ke via kuracisto kontrolu tion en via sekvonta enoficigo.

You can use the imperative form: Vere vi petu ke via kuracisto ...

Johannes

Thank you, Johannes!

I use deveti-devi-devegi, like the verb ridi.

Isn't there also "Vere, vi petu ke via kuracisto .... ....."?
I've seen that sort of usage in English and other non Indo European languages too, using an infinitive construction instead of "should", although I imagine it comes of more familiar than "devus", but for some probably gives them less headaches than trying to figure out why "dev-" is in the conditional tense

johmue:You can use the imperative form: Vere vi petu ke via kuracisto ...

Johannes

I'm just wondering if we should understand the words thus:

devas = must
devas ne = must not
ne devas = must not

(ok, so 'ne devas' could mean 'not have to', but there's a bit of a muddle about this one according to PMEG, so perhaps we should always stick to 'ne bezonas' or 'ne estas necese' for this!)

And then when we want to say 'should' then we should perhaps always use the form mentioned by johmue - verb +u

Eg.

You should learn more words = Vi lernu pli da vortoj.

(It seems people often say 'vi devas lerni pli da vortoj' for this same meaning, but are they perhaps wrong to do so? Afterall, if they do, then how are we supposed to know if they mean 'you should' or 'you must'?! - Is it a friendly suggestion, or a command?!)

As you can see, I kind of know the words, but I'm rather confused... But then I've never found a good explanation of this anywhere...

I normally consider the -u form without a pronoun to be a command, and the -u form with a pronoun to be a suggestion.

Petu al via kuracisto. - Ask your doctor (command).
Vi petu al via kuracisto. - You should ask your doctor (suggestion)

johmue:Use "nepre" if you think "devi" alone is too weak: Vi nepre devas pagi nun ...

That's a good suggestion, but it only differentiates between 'You really must/have to' (Vi nepre devas) and simply 'you must/have to' (vi devas)...

"Should" is trickier. Many Esperanto sentences written with "devas" seem to indicate that the real meaning intended is 'should', but then how can one word mean 'must' and 'should' at the same time?!

erinja:I normally consider the -u form without a pronoun to be a command, and the -u form with a pronoun to be a suggestion.

Petu al via kuracisto. - Ask your doctor (command).
Vi petu al via kuracisto. - You should ask your doctor (suggestion)

Yes, that seems like a good explanation. But how would the following sentence fit in with that:

"Vi devas peti al via kuracisto" - Does this simply mean 'You must/have to ask you doctor'. Surely, this can't also mean 'You should ask you doctor'?! Sorry for going on about this, but I really want to clear up the notion of 'should' in Esperanto. 'Devas' seems to be used by many for this, but it seems wrong. Your message as quoted above seems the only correct way.

When you search for 'should' in the Lernu dictionary, it comes up with 'devi'. Oh no, that is surely wrong?! Or can someone come up with an explanation?