The danger of neglecting the 'unknown knowns'

I REFER to your editorial headlined "Revisiting the 'unknowns' - known and unknown alike" (BT, Oct 29). While all three facets of Secretary Donald Rumsfeld's response were succinctly addressed in the editorial, the fourth category, "unknown known", was sorely neglected.

According to the Slovenian philosopher Slavoj Zizek, this fourth category is deemed to include "things that exist and influence our life", but we either do not realise their value or refuse to acknowledge knowing them.

In the context of your editorial, there is a great deal of uncertainty as to what the global economy will be like, despite our knowledge of the past, while the future is still unclear given the lack of precedence of our current situation, and hence the allusion to an "unknown unknown".