While he conceded that the public could not know for certain whether the secrecy is due to phone intercept evidence, Mr Ryder called for an "urgent review" into the provision which prevents disclosure and discussion of telephone intercept evidence which he said was "exceptional".

BBC: 'I'd prefer to know the truth' of Duggan death

The paper demonstrated the hypothesis through a complicated experiment in which college students were asked to make a judgment about something they could not know for certain -- guessing someone's weight in a photo -- before having their moods swayed either positively, negatively or neutrally by snippets from films intended to provoke either anger, euphoria or no strong feelings.

CNN: When emotion takes over

Walgreen may not know for certain which plans are steering big orders to mail vendors, but says it will find out using internal sleuthing.

FORBES: On The Cover/Top Stories

Some patients may not want to know and may be distressed to find out if they have genes that put them at higher risk for certain diseases.

WSJ: Making Gene Mapping Part of Everyday Care

We turn out to know a lot, for instance, about certain species of dinosaurs, he points out, not be cause they are the most important or exceptional, but because their fossils have been easy to collect.

FORBES: The Knowledge Revolution Is Not About Big Data, It's About Well-Connected Little Data