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Tung Quoc

#277248 Sat, 07 Oct 06 05:11 AM

She did very well on the exam. She must have studied hard. (1)

=She did very well on the exam. She should have studied hard. (2)

=She did very well on the exam. She ought to have studied hard. (3)

Is that right? If not, what is the difference btw them?

Quoc

Tung Quoc

Joined on Sun, Sep 17 2006

Regular Member (870)

Clive

#277265 Sat, 07 Oct 06 05:47 AM

Hi,

She did very well on the exam. She must have studied hard. (1)

=She did very well on the exam. She should have studied hard. (2)

=She did very well on the exam. She ought to have studied hard. (3)

Is that right? No, it's not.

If not, what is the difference btw them?

In #1, the second sentence suggests a reason for her success.

In #2 and #3, the second sentence gives the opinion that she needed to study more. This advice would be appropriate if she had failed. But she didn't fail.

eg She failed the exam. She should have studied hard. (2)

Best wishes, Clive

Clive

Joined on Thu, Oct 28 2004

Canada

Veteran Member (22,568)

El tango argentino es un pensamiento triste que se puede bailar (The tango argentino is a sad thought which can be danced) Enrique Santos Discépolo

CalifJim

#277306 Sat, 07 Oct 06 08:18 AM

See Post:67841.

CJ

CalifJim

Joined on Mon, Aug 2 2004

California

Veteran Member (17,791)

"There are no facts, only interpretations" - Nietzsche

milky

#277333 Sat, 07 Oct 06 09:49 AM

She did very well on the exam. She must have studied hard. (1) I conclude that she did study hard.

=She did very well on the exam. She should have studied hard. (2) I conclude that she didn't study hard. (Not a logical conclusion)

=She did very well on the exam. She ought to have studied hard. (3) I conclude that she didn't study hard. (Not a logical conclusion)

milky

Joined on Thu, Jan 15 2004

Senior Member (3,149)

Hume said that if we had perfect or complete descriptive knowledge of reality, we could not, by reasoning, derive a single valid "ought".