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general::
Phrase(s): the whys and wherefores of something
the reasons or causes relating to something. • I refuse to discuss the whys and wherefores of my decision. It’s final. • Bob doesn’t know the whys and wherefores of his contract. He just knows that it means he will get a lot of money when he finishes the work.
McGrawhill's American Idioms And Phrasal Verbs