A person who knows all the answers, has an opinion on everything, has a certainty backed up by rational argument, has very little possibility of further progress. Such a person is unlikely to walk away from a discussion with anything more than a reaffirmation of how right he or she has been all along.
Edward de BonoThe vertical thinker says: 'I know what I am looking for.' The lateral thinker says: 'I am looking but I won't know what I am looking for until I have found it.'
Edward de Bono