The vaccine deniers are people who deny that vaccines don't cause autism. That's a lot of negatives. More simply, they're people who assert that vaccines do cause autism. Obviously, the point of calling them "deniers" or "denialists" is to bring to mind Holocaust denial. A denier (as opposed to a skeptic) is someone who both flouts reason and evidence and is morally reprehensible for doing so. The flouting leads to some sort of egregious misbehavior. The Holocaust denier grossly dishonors the millions who suffered and perished in the death camps. The vaccine denier encourages people not to have their children vaccinated, exposing them and other kids to serious health risks.
For a while I've been thinking about the difference between a "denier" and a "skeptic" because I use the word "denier" in the third chapter of Animalkind to describe people who claim that animals have no conscious experiences, and specifically feel no pain. That's the term I use to refer to Peter Carruthers, Peter Harrison, and Stephen Budiansky. I do think they flout reason and evidence, and I do think they're morally reprehensible-- especially Peter Carruthers, because he explicitly draws out the implications of his stance on animal pain. He writes--
Much time and money is presently spent on alleviating the pains of brutes, which ought properly to be directed toward human beings, and many now are campaigning to reduce the efficiency of modern farming methods because of the pain to the animals involved. If the arguments presented here have been sound, such activities are not only morally unsupportable but morally objectionable. ("Brute Experience," p. 268)Did you pay for anesthesia when you had your dog neutered? How silly of you. Animals feel no pain! The money should have been put toward something more important--he tells us. And don't lets be fussing about factory farming and slaughterhouses. The animals feel nothing!
You might say that it's obvious to any reasonable person that the Holocaust did occur, and obvious to anybody who's studied the scientific evidence that vaccines don't cause autism. On the other hand, there's a real puzzle about what animals experience. So is it fair to call Carruthers & Co. "deniers"?
Perhaps this is the best way to explain why animal pain deniers deserve that name. The sort of doubt you can feel about animal suffering is the wrong type to ground decisions to withdraw pain relief from animals. It's armchair doubt, ivory tower doubt, the kind of doubt you can generate in a philosophy class. It's beyond a reasonable doubt that a dog will feel pain during surgery (see my chapter for discussion). So saying they don't, and consequently excoriating people for "alleviating the pains of brutes," really does involve a morally reprehensible mishandling of evidence.
The vaccine issue is interesting for lots of other reasons. More on that in another post.