for all I, you, etc. know
for all (one) knows
Said when one is uncertain or has limited details about something. I haven't talked to Marie in weeks, so, for all I know, she's not even coming to the dinner party tonight.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
for all ˈI, ˈyou, etc. know(spoken) used to emphasize that you somebody does not know something: She could be dead for all I know.
Farlex Partner Idioms Dictionary © Farlex 2017