There are known knowns; there are things we know. We also know there are known unknowns: that is to say we know there are some things we do not know. But there are also unknown unknowns – the ones we don’t know we don’t know.
Donald H Rumsfeld
There are known knowns; there are things we know. We also know there are known unknowns: that is to say we know there are some things we do not know. But there are also unknown unknowns – the ones we don’t know we don’t know.
Donald H Rumsfeld