The phrase "whys and wherefores" refers to reasons or explanations for something. When searching for synonyms, one could try using words like rationale, motive, justification, cause, or purpose. Each of these words conveys the idea of needing an explanation or reason for something. Additionally, words like reasoning, account, and explanation could be used to describe the act of providing the "whys and wherefores." It is always helpful to have a variety of synonyms in your vocabulary to avoid repetition, and enhance clarity in communication.