Why should anyone have thought that...?

[cannonkuo]

After all, Britain had been divesting colonies since World War II. The U.S. had been opposing colonialism as part of its own anti-colonial heritage. Why should anyone have thought that the British would decide to make a military stand on behalf of some islands and sixteen hundred islanders 8,000 miles away? (My Falklands War and Theirs—Jean J. Kirkpatrick)

Why did the author use "Why should anyone have thought that...?" instead of "Why should anyone think that...?"

Thank you very much.

 

[Flamenco1]

After all, Britain had been divesting colonies since World War II. The U.S. had been opposing colonialism as part of its own anti-colonial heritage. Why should anyone have thought that the British would decide to make a military stand on behalf of some islands and sixteen hundred islanders 8,000 miles away? (My Falklands War and Theirs—Jean J. Kirkpatrick)

Why did the author use "Why should anyone have thought that...?" instead of "Why should anyone think that...?"

Thank you very much.

• "have thought" is present perfect tense. It is used to talk about actions that started in the past and are still true today.
• "think" is the present tense.

The author is telling us that the thinking process was possibly valid in 1982, and continues to be valid to this day.

If he had used "think" it would position the thinking in the present.

 

[5jj]

• "have thought" is present perfect tense. It is used to talk about actions that started in the past and are still true today.
• "think" is the present tense.

Not really

Should have thought is a modal perfect form, in which have thought is the perfect infinitive. It frequently refers, as it does in Kirkpatrick's words, to past-time events which are not still true today.
Should think is a modal form, in which think is the bare infinitive.

 

[jutfrank]

After all, Britain had been divesting colonies since World War II. The U.S. had been opposing colonialism as part of its own anti-colonial heritage. Why should anyone have thought that the British would decide to make a military stand on behalf of some islands and sixteen hundred islanders 8,000 miles away? (My Falklands War and Theirs—Jean J. Kirkpatrick)

The perfect infinitive form is in step with the previous two past perfect tenses to create a background context to the war.

 

[Tdol]

They were surprised after the event.