postulate vs call for

postulate is a noun but call for is not a noun.

Word	Noun	Adjective	Verb	Adverb
postulate	Yes	No	Yes	No
call for	No	No	Yes	No

As verbs, postulate and call for are synonyms defined as:

Other synonyms of postulate include ask, demand, involve, necessitate, need, require, take.

postulate (noun)	call for (noun)
(logic) a proposition that is accepted as true in order to provide a basis for logical reasoning

postulate (verb)	call for (verb)
take as a given; assume as a postulate or axiom	request the participation or presence of
maintain or assert	express the need or desire for
require as useful, just, or proper	gather or collect
	require as useful, just, or proper