The analysis of opinion sharing by Dr Justin Coulson should be mandatory reading in the “conditions of use” for all users of social media (Everybody is an expert, 13/1). Preconceived ideas negatively filter new information, predisposing us to only believe what we like. Our opinions are often emotively charged, implying a slight to our ego if proven wrong. But it is not only social media users that are at risk. Group-think in large institutions where gossip festers is a much better model of this toxic human behaviour. Sharing ideas that generate kindness, unity and goodwill might be a good guide for all who want to be heard. I am happy to be guilty of optimism. Alan Sexton, North Parramatta. 14Jan2020.