When asked why someone said something idiotic or some group is advocating something moronic, I am apt to wearily reply that there is no defense against stupidity.
There is a defense and it works over the long run. It is called the truth.
It is interesting to watch how “the truth will out” as they say in detective novels. In our society, so in thrall to the mainstream press and media, the truth circulates swiftly through that portion of the population that first suspects something is amiss and then outward to the general population that can no longer ignore it.