Wherefore is one of those archaic words that is not yet quite obsolete. It is young enough that many people have heard of it, but old enough that many have forgotten what it means. It has survived mainly in the phrase “the whys and wherefores,” and in Juliet’s immortal line, “wherefore art thou Romeo?”1
Wherefore means “why,” or “for what reason.” It does not mean “where.” During the 13th century, English obtained several “where” words2: wherein, whereof, whereon, etc. These words can be “translated” as “in what,” “of what,” “on what,” etc.3 Wherefore is then “for what [reason].”
When Juliet says, “wherefore art thou Romeo?”4 she does not mean “Where art thou, Romeo?” but “Why art thou Romeo?” Why must Romeo be a Montague, an enemy of her family. The rest of her line brings this into context: “Deny thy father and refuse thy name. / Or if thou wilt not, be but sworn my love, / And I’ll no longer be a Capulet.”5 Likewise, “the whys and wherefores” are not “the whys and wheres” but “the whys and for-what-reasons.” So now you are no longer in danger of embarrassing yourself by using wherefore incorrectly.
1William Shakespeare, Romeo and Juliet, Act II, Scene ii
2Not to be confused with were-words, linguist relatives of the werewolf. 😉
3Miriam-Webster Dictionary, “Wherefore”
4William Shakespeare, Romeo and Juliet, Act II, Scene ii