help. Is this sentence correct?
I have got a sentence in my IB diploma textbook.
the debatable nature of much ethical knowledge is important to recognize and vital to understanding human behavior.
I was confused about the meaning of the sentence. I ask a colleague of mine to figure this out. but my collegue said that she thought this sentence is a kinda incorrect.
they right saying is
the debatable nature of much ethical knowledge is important to recognize and vital for (replace to with for) understanding human behavior
or
the debatable nature of much ethical knowledge is important to recognize and vital to understand (delete the ing) human behavior
which one of the three sentence above make sense?
Thanks a lot.

Question

help. Is this sentence correct?
I have got a sentence in my IB diploma textbook.
the debatable nature of much ethical knowledge is important to recognize and vital to understanding human behavior.
I was confused about the meaning of the sentence. I ask a colleague of mine to figure this out. but my collegue said that she thought this sentence is a kinda incorrect.
they right saying is 
the debatable nature of much ethical knowledge is important to recognize and vital for (replace to with for) understanding human behavior
or
the debatable nature of much ethical knowledge is important to recognize and vital to understand (delete the ing) human behavior
which one of the three sentence above make sense?
Thanks a lot.

Answer

Sentences #1 and #2 are both correct (in my opinion, “to” and “for” are both OK).   Here is the reason that I believe #3 is wrong:  the object of the preposition “to” or “for” should be a noun or a noun phrase — such as “understanding human nature.”  “Understand human nature” is not a noun phrase and so is not correct.

Answer

@Chris ur answer help a lot and make it fully understood . Thank u very much

Answer

The original is the best version.  "vital to" is a set phrase and the preposition "to" must be followed by a noun such as "comprehension" or a gerund such as "understanding."

The second version with "vital for" sounds odd. Google N-grams for English fiction shows that "vital to" is four times more common than "vital for."

The third version is grammatically wrong because "to" is a preposition in this context, and so, the gerund "understanding" is required.