"No head injury is too trivial to ignore"

I was looking at the book Introduction to Mathematical Thinking by Keith Devlin, and came across a question where the reader is asked to reformulate this sentence to avoid the unintended second reading:

No head injury is too trivial to ignore.

However, I couldn't really find any alternative meaning.

Any ideas about what the “unintended second meaning” might be?

Solution 1:

The basic meaning is litotes, reversal of the sentence:

Every head injury is serious enough to pay attention to it.

But you can completely twist the meaning, reading it in a straightforward manner that only after you finish parsing the sentence starts appearing as making no sense:

Lack of head injury is so trivial that you can't ignore it.

Only after you notice "triviality of issue rather encourages ignoring it" - the relation is reverse, the more trivial something the more prone to ignore it you are - that's when you stop and notice this way of parsing the sentence makes no sense and you must re-parse.

The ambiguity comes from no head injury meaning none of head injuries and an absence of head injury.

Solution 2:

What is meant is No head injury is trivial enough to ignore (or possibly Any head injury is too important to ignore). The original actually means that all head injuries should be ignored.

Solution 3:

No head injury is too trivial to ignore.

The phrase No head injury could potentially mean either of the following:

• Not a single (type/kind of) head injury (or, in other words, the presence of any head injury)
• Having no head injury (or, in other words, the absence of a head injury)

These two interpretations are contradictory.

A similar ambiguous construction is, "No news is good news".

Solution 4:

The ambiguity is whether "too" modifies "trivial" or "trivial to ignore." The latter is very, very weak, so to illustrate the idea more clearly, consider these examples:

"The diamond is too hard to cut." "The diamond is too hard to see." Now it should be clear that the first one has "too" modifying "hard" but the second has it modifying "hard to see."