“making critical decisions .. based on little or no knowledge”, and doing so with an air of complete assurance.

by expoƒunction

Rather than begin with the evidence and work towards a conclusion, the team members worked in the opposite direction. More egregiously, their scepticism about the possibility that something might really be wrong made them dismiss the need to gather more information …

… their conviction that nothing was wrong limited discussion and made them discount evidence to the contrary. In that sense the team succumbed to what psychologists call “confirmation bias” which causes decision makers to unconsciously seek those bits of information that confirm their underlying intuitions. These problems were also exacerbated by the team’s belief that it knew more than it did.

In other words, “they were making critical decisions .. based on little or no knowledge”, and doing so with an air of complete assurance.

The Wisdom of Crowds, Chapter 9, Committees, Juries and Teams: