Who's to say?

Who's to say?

1. No one really knows (to truth about or answer to something). A: "What does the future hold for you, now that you've left the music industry?" B: "Who's to say, really? I've always been interested in writing a novel, so I may pursue that." A: "Why on earth have they decided to go this route with the new software?" B: "Who's to say what convoluted analytics they employ to come up with their new designs?"
2. According to whose authority? Who's to say I can't take another holiday already? I have the days to take, and it doesn't conflict with anyone else in the office. I know we've had a tough season so far, but who's to say we can't go all the way and win the championship?
See also: to
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

who’s to ˈsay (...)?

(spoken) used to say that something might happen or might have happened in a particular way, because nobody really knows: Who’s to say we wouldn’t have succeeded if we’d had more time?
See also: to
Farlex Partner Idioms Dictionary © Farlex 2017
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References in periodicals archive ?
Who's to say? I think it's an attitude we both share," she said.