先不急着套用语法理论的模型，我们来看一看实际情况下shouldn't have to和should have to是如何使用的。

Mike Tallis had been going to Dr. Howard Diamond, a longtime pain management physician, for prescription painkillers for injuries he said he sustained at his job a decade ago. But when Tallis arrived that Tuesday, July 18, at Diamond's office, he found the doors locked and the office empty. Diamond had been arrested earlier that month on federal drug conspiracy charges that included conspiracy to distribute controlled substances, possession with intent to distribute controlled substances, health care fraud, aiding and abetting, and money laundering. "I shouldn't have to bury her," her sister, Kaylynn Curtis-Rhodes, told ABC affiliate WFAA. "I shouldn't have to get to the cemetery to see my sister."

这一段话的背景是医生滥用药物造成病人死亡。这里的shouldn't当然可以作认知性情态理解，即隐含了医生没有滥用药物的条件：If he had not been involved in the conspiracy, I shouldn't have to bury her.

但是这里的shouldn't语用上又不仅仅表达推测，它还带有很强烈的谴责的情态：医生不应该滥用药物。因此应当将这里should的用法划入道义性情态，以与下面这种仅表达推测的should区分开来：

If he had left yesterday, he should be here now.

道义性情态有一种很特殊的现象，就是表面上看是“这个人应该”，实际上却是“另一个人应该”。比如：

You shall have your money back tomorrow. （The Cambridge Grammar p.194）

这里表面上看是“你应该明天收到钱”，实际上是我在向你承诺“明天你会收到钱”。既然有承诺的语义成分，就应当划入道义性情态。

I shouldn't always have to tell you what to do.

这句话也是同样的情况：表面上是“我应该不用告诉你”，实际上暗含的是“你应该自己知道怎么做”，也就是道义性情态。

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然后我们看一看should have to怎么用。

Nobody should have to wait over three years to get a placement in long-term care when they need it.

这句话表面上看是should have to，可是它的主语是带有否定意义的nobody，所以它本质上依然是shouldn't have to。

He questioned why his 83-year-old father should have to go to a pub to watch games which are shown only on Sky.

这句话中的should本身几乎没有独立的情态意义，它的作用是加强疑问的语气：我为什么就非要去那里观看比赛？

Mr McIntyre said he did not believe the Canterbury Rugby Union should have to contribute to the building costs.

这句话中的should同样没有自身的情态，而是用来加强believe的语气：我不相信我们竟然要承担建筑费用。

这种用来加强句中其它成分的语气的should，语言学上称作“情态协调”（Modal Harmony, p.179）。

They should have to publish their business address and the fact that they run alongside an other business.

这一句话的背景是一家公司隐瞒了对消费者有用的信息。作者的意思是“应当设立相关规定，强制公司披露这些信息”。所以“应当”和“必须”放在一起并不是矛盾的。

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shouldn't是可以表达认知性情态的：

Michigan will be a double-digit win team again and shouldn't fall far from Big Ten title contention.

But the Note 8 shouldn't have issues due to a smaller battery size and more spacing around it.

This shouldn't be too hard.

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8月25日更新，答复语法探讨：

should既可以表示推测，也可以表示义务。这和它后面是静态还是动态动词并无关系。人的意志可以改变自身和环境的状态，这是显然的。

People should know the damages that have been done and understand the things that must be done to save it.（讨论保护环境）

We agree with their conclusion that we should remain united.

Letters to the editor should include author's name, address and phone number.

在I shouldn’t always have to tell you what to do这个结构中，因为你的无知造成了我必须指导你，这对于我而言这是一个客观因素，但是对于你而言这是主观因素。比较：

I always have to tell them that this is a soap opera...!

Perhaps you should tell us what you know that the rest of us don't know.

所以have to是针对我而言的，而should是向你提出要求，请你改变这个状态。