[General] must be or must have been?

[jiaruchan]

If he really said that, he must be crazy.

If he really said that, he must have been crazy.

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Can you tell me which is more proper? Are both acceptable?

[rlfwood]

They have different meanings. The first one says that he must be crazy now. The second one says that he must have been crazy when he said that (but perhaps his insanity was only temporary).

[jiaruchan]

Originally Posted by rlfwood

They have different meanings. The first one says that he must be crazy now. The second one says that he must have been crazy when he said that (but perhaps his insanity was only temporary).

Thank you. If I say: he must be crazy when (not if )he said that, is that ok and does it mean the same as 'he must have been crazy when he said that?

[Gillnetter]

Originally Posted by jiaruchan

Thank you. If I say: he must be crazy when (not if )he said that, is that ok and does it mean the same as 'he must have been crazy when he said that?

"Must be" is in the present tense - It must be raining now.
"He must have been crazy" is in the past tense.
It is incorrect to say, "He must be crazy when he said that", because the tenses are incorrect - Part is present and part is past.