Karl has given some good examples of cases that might be labeled subjunctive.  There is also the common use with the first person to refer to an internal future time or moral imperative: I should like to go now.  The moral may be accumulated with the social imperative so that we might could use a double modal:  I should ought to go now"  Perhaps the "should" is more internal moral obligation whereas the "ought to" has a more external social obligation.

Bruce 

--- [log in to unmask] wrote:

From: Karl Hagen <[log in to unmask]>
To: [log in to unmask]
Subject: Re: ought to/should
Date:         Wed, 28 Jan 2015 10:57:12 -0800

I assume you mean the difference in semantics. (In terms of syntax, 'should' selects a bare infinitive verb as a complement whereas 'ought' selects the to-infinitive.)

In the most common uses, should and ought are interchangeable, so in your examples, I would say they're synonymous. But there are a number of constructions where you can only use 'should', for example:

It is regrettable that he should be unhappy.
If he should be unhappy, apologize for me. 
How surprising it is that he should be unhappy.
I sent my mother flowers lest she should think I had forgotten her.


> On Jan 28, 2015, at 10:25 AM, Scott Woods <[log in to unmask]> wrote:
> 
> Dear List,
> 
> How would you explain the difference between "ought to" and "should"? 
> 
> You ought to study. You should study. You ought to go home. You should go home. We ought to exercise. We should exercise.
> 
> Thanks,
> 
> Scott Woods
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