In the sentence:

The two methods require two different kinds of prior information

a colleague of mine suggests that it should be "kind of" instead.

I was quite certain that the first form was correct, but reading various online sources on singular vs. plural use in relation to "kind of" has got me confused. Still, it seems to me that the examples where it is a bit ambiguous are those where the quantity is implied by how you interpret the sentence. In the current case, I still lean towards "two kinds" because it seems it is explicitly "kind" there are two of. Which one is right?

NB: I am not a native English speaker.


2 Answers 2


It makes sense for kind to be in plural form in the sentence "The two methods require two different kinds of prior information." because here kind functions as a rather simple count noun.


  1. a class or group having characteristics in common; sort; type ⇒ two kinds of people
  2. an instance or example of a class or group, esp a rudimentary one ⇒ heating of a kind
  3. essential nature or character ⇒ the trials were different in kind from any that preceded them

Your friend may have confused it with the phrase kind of which expresses vagueness (or is sometimes used as a meaningless filler).

kind of


  1. adverb somewhat; rather ⇒ kind of tired
  2. sentence substitute used to express reservation or qualified assent ⇒ I kind of figured it out.

Not a native speaker.

I would go for “two kinds of”.


I only listen to two kinds of music. Jazz and Blues.


I only listen to one kind of music. Rock'n'Roll.

However, it's similar to "two parts of"/"two part of". "Two part of" sounds weird. It evokes in me that it's "The second part of something" ;D

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