How to understand the structure "had to have done"?

Question

From TED (Start from 1:42:

But novel, the second thing, is that nobody had to have said it.

How to understand the structure "had to have done"?

I think it sounds better to me without the "had to" : but novel, the second thing, is that nobody had said it.

Answer 1

It’s using “have” in the sense of need or requirement, as in

• I’m hungry, so I have to go to the grocery store (and buy some food).
• To cross an international border, you have to have a passport.

combined with the present perfect:

• The door was squeaky yesterday and it’s quiet today, so somebody has to have oiled it.
  • i.e, somebody must have oiled the door between yesterday and today.

Now consider these ways of saying almost the same thing:

• A millionaire has a million dollars.
• Every millionaire has a million dollars.
• A millionaire is a person who has a million dollars.
• To be a millionaire, a person has to have a million dollars.

The last two are essentially stating definitions, and the last one is explicitly specifying a characteristic that a person must satisfy in order to meet the definition.  And that’s what the speaker in the TED talk is saying:

… the definition of creativity that a lot of people go with is “appropriate novelty”.  For something to be appropriate, it has to be realistic.  …  But novel, is the second thing, is that nobody had to have said it.

She explicitly says that she’s talking about definition(s).  The second sentence,

For something to be appropriate, it has to be realistic.

is almost exactly the same form as my last “millionaire” definition — realism is a necessary characteristic of appropriateness.  Given that context, the last sentence should be interpreted as

But novel … means that nobody had to have said it.

And here’s a larger interpretation:

You said something appropriate / realistic.  Was it creative?  Was it novel?  Well, nobody had said it before you did.  [Using past perfect because the sentence refers to events that might or might not have happened before a time in the past that’s already under discussion.]  OK, good, the fact that you’re the first person to express the idea is a necessary condition for your idea to be considered novel.

For it to be novel, it had to be the case that nobody had said it before you did.

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But there’s another complication.  Consider this fairly straightforward sentence:

1. The book report was an optional (elective) assignment; nobody had to do it.

… in other words, nobody was required to do the book report assignment.  Compare to this dubious usage:

2. For a boycott to be effective, nobody has to buy the product.

Thinking about the whole sentence, it clearly means that it has to be the case that nobody buys the product.  In other words, everyone is required to not buy the product, or (using the passive voice) the product has to be bought by nobody.  This is what Eddie Kal is talking about in his comment.  You have to use context to recognize this usage of “nobody has to”.

Answer 2

This construction is regarded as informal. It actually means, "nobody had to say it because it was taken as a given/clearly understood."