“Suppose you think, as I do, that knowing that something is the case (e.g. that the MMR vaccine is safe) requires being reasonably confident that it’s the case and also having the right to be confident. In that case, anything that effectively undermines my confidence or right to be confident is a threat to my knowledge. So, for example, getting me to doubt the safety of the MMR vaccine by spreading spurious but convincing stories about links between MMR and autism can prevent me from knowing that it’s safe.” 3AM Magazine