I'm seeking the word that describes a character trait for someone who, when given a system of beliefs, methods, or views, will sort through and accept or emulate only the best or purposeful parts of the system, while disregarding the irrational, superfluous, or unnecessary parts of said system.
I'm looking for adjective, used to describe the tendency of a person to act in a certain manner. I believe it ends in the suffix -ive, though I cannot be sure.
"Arya may see the purpose of their system of beliefs and the good that they do, yet she often argues at the inconsistent narratives and irrational acceptance of blind faith that such views require. She can be very ____ in matters such as these."
I'm looking for a neutral connotation.
Further context (long shot): it is used in one of the Inheritance Cycle books for one of the main characters, Eragon, to describe his love interest Arya, in a similar manner as posted above. I simply cannot find or remember the exact wording, or the chapter that it was used in, even though I have searched the definition of this word before.
A synonym for such a trait, used as a verb, would be "to cherry-pick".
e.g. "Bob likes to go to church, but when it comes to the Bible, he cherry-picks what to believe and what not to believe."